5th Workshop of Computational Chemistry and Molecular

Transcripción

Facultad de Ecología y Recursos Naturales
Doctorado en Fisicoquímica Molecular
5th Workshop of
Computational Chemistry and
Molecular Spectroscopy
October 17-20, 2006
Balneario Banco Central
Punta de Tralca, Chile
www.unab.cl/workshop
3th Workshop of Computational Chemistry and Molecular Spectroscopy
October 23 – 25, 2002, Olmué, V Región, Chile
Cover: Relativistic Fukui function of Re6S8Cl64-.
October 19 – 22, 2004, Balneario Banco Central, Punta de Tralca, Chile
Cover: ELF of Cu7
October 17 – 20, 2006, Balneario Banco Central, Punta de Tralca, Chile
Cover: Dirac spin density of the luminescent Re6S8Cl63- cluster.
5th. Workshop of Computational Chemistry and
Molecular Spectroscopy
October 17 – 20, 2006
Balneario Banco Central, Punta de Tralca, Chile
Isidoro Dubornais S/N°, El Quisco V Región
Telephone: (56)-35- 47 1010 - Fax: 56-35- 47 1398
[email protected]
P re fa ce
PREFACE
The Workshop of Computational Chemistry and Molecular Spectroscopy is an
academic activity organized every two years by the Ph.D. Program in Molecular
Physical Chemistry** of the Universidad Andrés Bello.
Is a traditional scientific meeting that seeks to enhance the academic interactions
between recognized researchers and graduate students enrolled in several
doctoral programs of Chilean Universities.
During this 5th version we will discuss recent advances in quantum molecular
sciences and
molecular dynamics on topics of material science, molecular
magnetism and electronics, crystal and molecular engineering, nanotubes and
functional polymers, nanotechnology, electronic structure and reactivity of
molecular precursors, and protein-membrane simulations.
We are grateful to all participants for their significant contributions that made this 5th
Workshop of Computational Chemistry and Molecular Spectroscopy possible.
Our gratitude also goes to our sponsors and to the Universidad Andrés Bello for
their support.
Ramiro Arratia-Perez
Chairman, Organizing Committee
*
The Ph.D. program in Molecular Physical Chemistry of the Universidad Andres Bello has been accredited by government
commissions (CONAP) on May 2006.
October 17-20, 2006, Punta de Tralca, Chile
1
J.J. Thomson
The Nobel Prize in Physics 1906
Joseph John Thomson
was born in Cheetham
Hill,
a
suburb
of
Manchester on December
18, 1856. He enrolled at
Owens
College,
Manchester, in 1870, and
in 1876 entered Trinity
College, Cambridge as a
minor
scholar.
He
became
a Fellow
of
Trinity College in 1880,
when he was Second
Wrangler
and
Second
Smith's Prizeman, and he
remained a member of the College for the rest of
his life, becoming Lecturer in 1883 and Master in
1918. He was Cavendish Professor of Experimental
Physics at Cambridge, where he succeeded Lord
Rayleigh, from 1884 to 1918 and Honorary
Professor of Physics, Cambridge and Royal
Institution, London.
Thomson's early interest in atomic structure was
reflected in his Treatise on the Motion of Vortex
Rings which won him the Adams Prize in 1884. His
Application of Dynamics to Physics and Chemistry
appeared in 1886, and in 1892 he had his Notes on
Recent Researches in Electricity and Magnetism
published. This latter work covered results obtained
subsequent to the appearance of James Clerk
Maxwell's famous "Treatise" and it is often referred
to as "the third volume of Maxwell". Thomson cooperated with Professor J. H. Poynting in a fourvolume textbook of physics, Properties of Matter
and in 1895 he produced Elements of the
Mathematical Theory of Electricity and Magnetism,
the 5th edition of which appeared in 1921.
In 1896, Thomson visited America to give a course
of four lectures, which summarised his current
researches, at Princeton. These lectures were
subsequently published as Discharge of Electricity
through Gases (1897). On his return from America,
he achieved the most brilliant work of his life - an
original study of cathode rays culminating in the
discovery of the electron, which was announced
during the course of his evening lecture to the
Royal Institution on Friday, April 30, 1897. His
book, Conduction of Electricity through Gases,
published in 1903 was described by Lord Rayleigh
as a review of "Thomson's great days at the
Cavendish Laboratory". A later edition, written in
collaboration with his son, George, appeared in two
volumes (1928 and 1933).
Thomson returned to America in 1904 to deliver six
lectures on electricity and matter at Yale University.
They contained some important suggestions as to
the structure of the atom. He discovered a method
for separating different kinds of atoms and
molecules by the use of positive rays, an idea
developed by Aston, Dempster and others towards
the discovery of many isotopes. In addition to those
just mentioned, he wrote the books, The Structure
of Light (1907), The Corpuscular Theory of Matter
(1907), Rays of Positive Electricity (1913), The
Electron
in
Chemistry
(1923)
and
his
autobiography,
Recollections
and
Reflections
(1936), among many other publications.
Thomson, a recipient of the Order of Merit, was
knighted in 1908. He was elected Fellow of the
Royal Society in 1884 and was President during
1916-1920; he received the Royal and Hughes
Medals in 1894 and 1902, and the Copley Medal in
1914. He was awarded the Hodgkins Medal
(Smithsonian Institute, Washington) in 1902; the
Franklin Medal and Scott Medal (Philadelphia),
1923; the Mascart Medal (Paris), 1927; the Dalton
Medal (Manchester), 1931; and the Faraday Medal
(Institute of Civil Engineers) in 1938. He was
President of the British Association in 1909 (and of
Section A in 1896 and 1931) and he held honorary
doctorate degrees from the Universities of Oxford,
Dublin, London, Victoria, Columbia, Cambridge,
Durham, Birmingham, Göttingen, Leeds, Oslo,
Sorbonne, Edinburgh, Reading, Princeton, Glasgow,
Johns Hopkins, Aberdeen, Athens, Cracow and
Philadelphia.
In 1890, he married Rose Elisabeth, daughter of Sir
George E. Paget, K.C.B. They had one son, now Sir
George Paget Thomson, Emeritus Professor of
Physics at London University, who was awarded the
Nobel Prize for Physics in 1937, and one daughter.
From Nobel Lectures, Physics 1901-1921, Elsevier
Publishing Company, Amsterdam, 1967
This autobiography/biography was first published in
the book series Les Prix Nobel. It was later edited
and republished in Nobel Lectures. To cite this
document, always state the source as shown above.
For more updated biographical information, see:
Thomson,
Joseph
John,
Recollections
and
Reflections. G. Bell and Sons: London, 1936.
J.J. Thomson died on August 30, 1940.
Copyright © The Nobel Foundation 1906
5h Workshop of Computational Chemistry and Molecular Spectroscopy
2
Sponsors
SPONSORS
UNIVERSIDAD ANDRÉS BELLO
Facultad de Ecología y Recursos Naturales
Vicerrectoría de Investigación y Postgrado
Vicerrectoría Académica
www.unab.cl
SUDELAB
Lira 1396
Fono: (56-2) 555 94 87
Fax: (56-2) 554 00 10
Santiago, Chile
[email protected]
IVENS S.A.
Av. Los Leones 3028 ,
Phone: (56-2) 204 40 05
Fax: (56-2) 209 13 14 - (56-2) 209 29 43
Ñuñoa, Santiago, Chile
[email protected]
SOCIEDAD CHILENA DE QUÍMICA
Universidad de Concepción
Concepción, Chile
www.schq.cl
INICIATIVA CIENTÍFICA MILENIO
Núcleo De Mecánica Cuántica Aplicada y
Química Computacional
www.nucleomileniocuantica.cl
3
Program
TUESDAY, OCTOBER 17
MORNING
8:45
10:30 – 11:30
Bus to Punta de Tralca: República 252
Registration
60 min.
11:30 – 12:30
Opening Ceremony
Academic Vice rector Rolando Kelly J.
Universidad Andrés Bello
60 min.
13:00 – 15:00
AFTERNOON
15:00 – 15:30
Setting up Posters
30 min.
15:30 – 16:15
Plenary Lecture 1
Chemical Quantum Diabatic States Approach as Complementary to Adiabatic
BO procedures: On the he role of spin-orbit interaction in chemical dynamics
and reaction mechanisms
O. Tapia, Uppsala University, Sweden
10
45 min.
16:15 – 16:25
Discussion
16:25 – 16:45
16:45 – 17:05
Oral 1
Inclusion of oligomers in PHTP nanochannels. Conformational and
spectroscopic aspects using ONIOM and time dependent methodologies.
Sergio O. Vásquez A., Universidad de Chile.
17
20 min.
17:05 – 17:25
Oral 2
Rationalization of Charge Transfer Mechanisms Involving Porphyrin Derivatives
Metal Complexes
Gloria I. Cárdenas-Jirón, University of Santiago de Chile.
18
20 min.
17:30 – 19:30
Poster Presentation
90 min.
20:00
4
Program
WEDNESDAY, OCTOBER 18
MORNING
7:00 – 8:30
9:00 – 9:45
Plenary Lecture 2
Pentalene and Acepentalene Coordination to Transition Metals: a DFT analysis
Jean-Yves Saillard, Université de Rennes, France
11
45 min.
9:45 – 9:55
Discussion
10:00 – 10:20
10:20 – 10:40
Oral 3
Density Functional Theory Studies on Ferrocenyl-Diimine Complexes
Mauricio Fuentealba, Universidad de Chile, Chile
19
20 min.
10:40 – 11:00
Oral 4
Multiplicity changes in atoms under pressure
Doris Guerra, Universidad Andrés Bello, Chile
20
20 min.
11:00 – 11:20
11:20 – 11:40
Oral 5
Effect of Ni(II), Cu(II) and Zn(II) Association on the keto-enol Tautomerism of
Thymine
Elizabeth Rincón B., Pontificia Universidad Católica de Chile
21
20 min.
11:40 – 12:00
Oral 6
Theoretical Study of Aromatic Transition State and the Α-Effect
Paula Jaramillo, Universidad Andrés Bello, Chile
22
20 min.
13:00 – 15:00
5
Program
WEDNESDAY, OCTOBER 18
AFTERNOON
15:00 – 15:45
Plenary Lecture 3
The Many Faces of the Materials Chemistry and Physics of the OrganicInorganic Interface
Patrick Batail, CNRS-Université d’Angers.
12
45 min.
15:45 – 15:55
Discussion
15:55 – 16:15
Oral 7
Theoretical Study on the Electronic Spectrum of Bi- and Tri-nuclear Pt(II)-Au(I),
Pt(II)-Ag(I), Pt(II)-Pt(II) and Pt(II)-Pd/II) Complexes
Fernando Mendizabal, Universidad de Chile, Chile
23
20 min.
16:25 – 16:45
16:45 – 17:05
Oral 8
24
A Molecular Model Potential Study of Molecular Wires
Ricardo Letelier D., Universidad de Chile
20 min.
17:05 – 17:25
Oral 9
25
Orbital Hardness in Single Monoatomic Anions
Mauricio Barrera, Pontificia Universidad Católica de Chile
20 min.
17:30 – 19:30
Poster Presentation
90 min.
20:00
6
Program
THURSDAY, OCTOBER 19
MORNING
7:00 – 8:30
9:00 – 9:45
Plenary Lecture 4
Ab initio calculations optical properties including e-h correlations
Niels E. Christensen, University of Aarhus, Denmark
13
45 min.
9:45 – 9:55
Discussion
10:20 – 10:40
Oral 10
Fe adatoms along Bi nanolines on H/Si(001): Patterning atomic magnetic chains
Walter Orellana, Universidad de Chile, Chile
20 min.
26
10:40 – 11:00
Oral 11
Procrustes analysis in the study of geometrical similarity effects
Verónica Jiménez, Universidad de Concepción, Chile
20 min.
27
11:20 – 12:05
Plenary Lecture 5
Molecular assembly and templating for nanotechnology
Werner J. Blau, Trinity College, Dublin, Ireland.
45 min.
14
12:05 – 12:15
Discussion
11:00 – 11:20
AFTERNOON
14:45 – 20:00
Free Time
20:00 – 22:00
22:30
Social
♫♪
7
Program
FRIDAY, OCTOBER 20
MORNING
7:00 – 8:30
9:00 – 9:45
Plenary Lecture 6
Simulación Molecular de Proteínas Transmembranales
Fernando Danilo Gonzalez-Nilo, Universidad de Talca
15
45 min.
9:45 – 9:55
Discussion
10:00 – 10:20
10:20 – 10:40
Oral 12
Simulación Molecular de la Interacción entre PIP2 y el canal TRPV1. (Molecular
simulation of the PIP2-TRPV1 channel interaction.)
C. Mascayano, Centro de Bioinformática y Simulación Molecular, Universidad
de Talca, Chile
28
20 min.
10:40 – 11:00
Oral 13
Análisis Estructural del Poro del Canal de K+ HSLO a Través de Simulaciones
de Dinámica Molecular.
W. González, Universidad de Talca, Chile
29
20 min.
11:00 – 11:20
Oral 14
NMR and Molecular Modeling studies of cyclodextrin-catechin complexes
Carolina Jullian, Universidad de Chile
30
20 min.
11:20 – 11:40
Round Table and Discussions
12:00 – 13:00
Poster withdrawal
13:00 – 14:30
15:00
RETURN TO SANTIAGO
8
PLENARY LECTURES
9
Plenary Lecture 1
Chemical Quantum Diabatic States Approach as Complementary to
Adiabatic BO procedures: On the he role of spin-orbit interaction in chemical
dynamics and reaction mechanisms
O. Tapia
Department of Physical and Analytical Chemistry, Uppsala University, Box 579. S-751 23 Uppsala, Sweden
In this work we explore a possibility offered by Pauli Hamiltonian to study chemical reactions in a
way complementary to the semi-classical Born-Oppenheimer (BO) approach. This operator is the
sum of the Coulomb Hamiltonian, HC and spin orbit interaction operator, HSOI. First we examine the
theory without electronuclear separability. Thereafter, separability leads to electronic Hamiltonians
that are incommensurate to HC; this fact is carefully examined. The result is a better understanding
concerning the complementarity between diabatic and adiabatic approaches; they are just models not
approximations to the exact problem. The diabatic model still permits electronic quantum states so
that the linear superposition principle holds. Reaction coordinate in real space of nuclear positions
can be defined as usual. Chemical mechanisms incorporate singlet and triplet excited states to help
untangle covalent states thereby coupling reactant and product closed shell channels. This
corresponds to a four-state description with fully diabatic potential energy functions. A secular
equation incorporating HSOI in the 4-state base set for each relevant value of the reaction coordinate
lead to quantum mechanical description of the chemical change. The scheme is well adapted to
study Jahn-Teller effects. The connections to BO scheme are surprising. The energy expectation
value with the lowest energy root along the reaction path is just a BO-like potential energy function.
It turns out that both methods can be used in complementary ways. On the one hand, conic
intersections are defused as problem but are given a guiding property to find out bottleneck regions.
On the other hand, use of present day computer technology can be adapted to examine diabatic
processes. A generalized Marcus-like scheme obtains. Numerical examples will be discussed. We
will all gain by using these models in an intelligent manner dictated by the problems at hand.
References
Arteca, G., Tapia, O.; 2005, J. Math.Chem. 37, 389-408
Tapia, O., Polo, V., Andres, J.; 2006, in Recent Advances in the Theory of Chemical and
Physica Systems, pp. 177-196, Julien, J.-P. et al. (Editors) Springer
Tapia, O.; 2006, J.Math.Chem. ISSN: 0259-9791 (Paper) 1572-8897 (Online).
DOI: 10.1007/s10910-005-9012-6
Acknowledgments
O. T. thanks the Millennium Nucleus for Applied Quantum Mechanics and Computational
Chemistry, Grant No. P02-004-F (MIDEPLAN-CONICYT, Chile) for inviting him to Chile.
10
Plenary Lecture 2
Pentalene and Acepentalene Coordination to Transition Metals: a DFT
analysis
J.-Y. Saillard
UMR 6226 Sciences Chimiques de Rennes, Université de Rennes 1, 35042 Rennes Cedex, France.
DFT calculations have been carried out on a series of real1 and hypothetical compounds of the type
CpM(pn), (CO)3M(pn), M(pn)2, (CpM)2(pn), [(CO)3M]2(pn) and M2(pn)2 (M = transition metal, pn
= pentalene). A rationalization of the bonding in all the already known compounds is provided, as
well as in (so far) hypothetical stable complexes.2 Depending on the electron count and the nature of
the metal(s), the η2 (predicted), η3, η5, η9 or intermediate coordination modes can be adopted. In the
case of the mononuclear species, the most favored closed-shell electron counts are 18 and 16 metal
valence electrons (MVE). In the case of dinuclear species, it is 34 MVE’s. However, other electron
counts can be stabilized, especially in the case of dinuclear complexes.
Fe(C8H6)2
(CpV)2(C8H6)
Rh2(C8H6)2
Calculations carried out on a related series of complexes of acepentalene3 predict that the unstable
acepentalene molecule can be stabilized by complexation to one, two (similarly to pentalene) and
even three metal centers, giving rise to compounds which should be isolable.
(CpFe)2(C10H6)
1
2
3
Zr(C10H6)2
[Nb3(C10H6)2]+
F. G. N. Cloke, Pure Appl. Chem. 2001, 73, 233-238.
S. Bendjaballah, S. Kahlal, K. Costuas, E. Bévillon, J.-Y. Saillard, Chem. Eur. J. 2006, 12, 2048-2065
A. de Meijere, R. Haag, F.-M. Schüngel, S. I. Kozhushkov, I. Emme, Pure & Appl. Chem. 1999, 71, 253-264 .
11
Plenary Lecture 3
The Many Faces of the Materials Chemistry and Physics of the OrganicInorganic Interface
Patrick Batail
Laboratoire Chimie, Ingénierie Moléculaire et Matériaux (CIMMA), UMR 6200 CNRS-Université d’Angers. UFR
Sciences, 2 Boulevard Lavoisier, 49045 Angers, France. [email protected]
This contribution to the 5th Worshop of Computational Chemistry and Molecular Spectroscopy is
about how the chemistry and physics of anisotropic, weak intermolecular interactions act in unison
in low dimensional hybrid organic-inorganic solids. The talk will focus on a solid state chemist
approach of current dimensionality issues in molecular solids supporting strongly correlated
electronic systems. An attempt at formulating molecular materials chemistry targets in response to
the perception of current theoretical dreams in the rich physics of systems of strongly correlated
electrons in one-dimension will be presented. These include the engineering of crystals where
interdependence of redox state and hydrogen bonding within self-complementary motifs, are
coupled to collective electronic instabilities, molecular motion, and charge localization. In addition,
this approach will be extended to reach out toward the issue of field effects in monomolecular πfunctional nano-(meso) wires, and over to the new field of mineral liquid crystals and mesophases
obtained by auto-assembly of nanostructured covalent mineral objects.
12
Plenary Lecture 4
Niels Egede Christensen and Robert Laskowski*
Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C, Denmark.
Electronic structure calculations based on the density-functional theory, even in the local
approximations (LDA, GGA) have been very successful in describing many physical properties of
solids in the past, even dielectric and optical properties (in some cases only after some corrections
(GW and other corrections to energy gaps)). We shall demonstrate this by comparing absorption
spectra derived from such effective one-electron theories to experimental data.
However, theories of optical excitations in solids, which are based on such standard band-structure
calculations omit essential interactions, in particular the correlations between the photoexcited
electron and the hole. This e-h correlation influences the states in the gaps of semiconductors
(excitons) as well as spectral positions and intensities in the continuum regime. We discuss here
calculations, which estimate these effects in three semiconductors, GaN, ZnO, and AlN by solving
the Bethe-Salpeter Equation (BSE) [1] using the density functional theory as a starting point.
Although these compounds crystallize in the same hexagonal (wurtzite) structure there are
differences in their band structures, which influence the excitonic effects. The relative energies of
the uppermost three states at the valence band maximum (VBM) result from the combined action of
the crystal field splitting (CFS) and the spin-orbit coupling (SOC). The SOC is positive at the VBM
of GaN and AlN, negative in ZnO. The CFS is positive in GaN and ZnO, but negative (and large in
magnitude) in AlN. A calculation of the full spectra by a diagonalization of the BSE Hamiltonian is
not practical, and instead we use a time evolution algorithm [2]. The exciton states in the gaps are
calculated directly by taking advantage of the short range in k-space of these exciton wavefunctions.
We discuss mainly exciton binding energies, their dependences on structural parameters and the
effects of the differences in VBM states in the three compounds. For AlN we further examine the
hydrogen-atom like model for excited exciton states [3]. Finally some recent calculations on the
pressure dependence of excitons in AlN will be presented. Some of the results obtained so far have
been described in Refs. [4,5,6]
* Present address: Inst. of Materials Chemistry, Technical University of Vienna, Austria.
[1]
[2]
[3]
[4]
[5]
[6]
L.J. Sham and T.M. Rice, Phys. Rev. 144, 708 (1966).
W.G. Schmidt, S. Glutsch, P.H. Hahn, and F. Bechstedt, Phys. Rev. B 67, 85307 (2003).
R.J. Elliott, Phys. Rev. 108, 1384 (1957)
R. Laskowski, N.E. Christensen, G. Santi, and C. Ambrosch-Draxl, Phys. Rev. B 72, 035204 (2005).
R. Laskowski and N.E. Christensen, Phys. Rev. B 73, 045201 (2006), PRB 74, 077203 (2006).
R. Laskowski and N.E. Christensen, physica status solidi (b), accepted (2006).
13
Plenary Lecture 5
Molecular Assembly and Templating for Nanotechnology
Werner J. Blau
School of Physics, Trinity College, Dublin, Ireland. [email protected]
On a molecular scale, the accurate and controlled application of intermolecular forces can lead to new, previously unachievable,
nanostructures. This is why molecular self-assembly (MSA) is a highly topical and promising field of research in nanotechnology
today. MSA encompasses all structures formed by molecules selectively binding to a molecular site without external influence. With
many complex examples all around us in nature (ourselves included), MSA is a widely observed phenomenon that has yet to be fully
understood.
Being more a physical principle than a single quantifiable property, it appears in physics, chemistry, and biochemistry, and is
therefore truly interdisciplinary. The problem to date with researching the fundamental physics behind MSAs has tended to be that
prime examples of MSAs are mainly found in the biological sciences. Biomolecular assemblies, such as light harvesting antenna
complexes found in some bacteria, are sophisticated and often hard to isolate, making systematic and progressive analyses of their
fundamental physics very difficult. What in fact are needed are simpler MSAs, the constituent molecules of which can be readily
synthesized by chemists to a high degree of purity, high-quality sample preparation, chemical purity, and known sample history that
are paramount in MSA research. These molecules should self-assemble into simpler constructs that can be easily assessed with
current experimental techniques.
At present, there is a huge global research effort targeted at carbon nanotubes. These structures are being investigated for applications
ranging from actuators to reinforcement agents, nanoelectronic devices to controlled drug-release agents—with each application
requiring a different, precisely defined physical and/or electronic structure. A major drawback of carbon nanotubes, however, is our
apparent lack of structural control, which arises because they are formed by either a gas-phase or a plasma process. MSA and
nanotemplating appear to open alternative routes to more controlled monodisperse structures.
In this lecture, I will summarise some of our approaches to address these issues and give both experimental and simulation results.
Particular examples will include
• Using nanoporous templates such as porous Alumina membranes to create various inorganic and polymeric nanowire structures.
• Templated assembly of molecules on Carbon Nanotubes to create new photonic and electronic materials and solubilize the
template
• Controlled self-assembly of functionalised discotic molecules to for MSE nanowires
Demonstrating that synthetic molecules can form ordered MSAs is a key step.
However, attaining a small degree of functionality with simple MSAs will be very significant, as it may indeed open up new avenues
for investigating complex MSAs and other nanosystems. Known and functional MSAs will be very useful as local probes to
investigate more complex MSAs. In other words, MSAs could become the nanotools of the future.
W.J. Blau & A.J. Fleming, Science 304 (2004) 1457
14
Plenary Lecture 6
Gonzalez-Nilo, Fernando Danilo
Centro de Bioinformática y Simulación Molecular (CBSM), Universidad de Talca.
La estructura de las proteínas transmembranales ha sido un enigma de los últimos tiempos, sin
embargo, las revolucionarias técnicas de cristalografía de rayos X implementadas por Roderick
Mackinnon (Nobel 2003), han permitido tener una visión real de la organización de estas proteínas
en las membranas. Una familia de estas proteínas son los canales de K+, claves en el sistema
nervioso y en la transmisión de impulsos eléctricos. En este ámbito la simulación molecular ha
cobrado un importante rol en el análisis de las propiedades energéticas, estructurales y dinámicas de
estas proteínas. Unos de los sistemas mas complejos de analizar son las proteínas transmembranales,
las que requieren de ser simuladas inmersas en una bicapa lipídica, debido a que las propiedades
estructurales de estas proteínas son moduladas por interacciones proteína-lípido. Estos sistemas
junto con modelos de solvente explicito (TIP3P) generan sistemas de miles de átomos, que requieren
de sofisticados métodos de análisis.
Recientemente, hemos realizado un hallazgo muy interesante en los canales TASK2, respecto del
estado de protonación de la Arg. La Arg con pKa de 12,1 se caracteriza por ser eminentemente
cargado bajo casi cualquier condición del medio, sin embargo, nuestros estudios de simulación
molecular han logrado identificar a priori a una Arg como sensor de canales activados por pH. Esta
Arg, según su estado de protonación, actúa como un regulador del potencial electrostático del filtro
de selectividad, modulando de esta forma la conductancia del canal. Esta hipótesis fue validada
experimentalmente mutando este residuo por Lys, His y Ala, obteniendo resultados que indican que
esta Arg posee un corrimiento de pKa de más de 6 unidades de pH. Este fenómeno fue estudiado
utilizando Dinámica Molecular y Mecánica Cuántica, dando resultados que contradicen dogmas
clásicos sobre el estado de protonación de los aminoácidos en las membranas celulares.
Agradecimientos: Fondecyt #1040254
15
ORAL LECTURES
16
Oral Lecture 1
Inclusion of oligomers in PHTP nanochannels. Conformational and
spectroscopic aspects using ONIOM and time dependent methodologies.
Sergio O. Vásquez A.
Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de
Chile. Tupper 2069. Santiago. CHILE.
Inclusion of guest species in tight cavities inside the supramolecular Perhydrotriphenylene (PHTP)
crystal host, induce changes in geometry and spectroscopic properties of the guest molecules. A
two-layer ONIOM study of models of the supramolecular architecture of inclusion compounds
based on Diphenylhexatriene (DPH), Terphenylene (P3) and Quinquethiophene (T5) show that the
observed conformational disorder in this kind of molecular systems is subject to some constraints:
there is an important degree of order inside the nanochannels preventing free rotational orientation
of the guest molecules as well as free translational distribution in the axial direction of the channels.
This kind of unidimensional systems are interesting models for UV to visible down-conversion
energy transfer processes through sequential energy transfer processes. Excited states of guest units
were studied using ZINDO and time dependent ab-initio calculations.
Acknowledgements. The author acknowledges the financial support of this research from Fondecyt Grant
1030662, and Núcleo Milenio de Mecánica Cuántica Aplicada y Química Computacional Grant P02-004-F.
17
Oral Lecture 2
Rationalization of Charge Transfer Mechanisms Involving Porphyrin
Derivatives Metal Complexes
Franklin Rosales-Salazar1, Cristhian Berríos1, Verónica Paredes-García2, Diego
Venegas-Yazigi3, Gloria I. Cárdenas-Jirón1
1
2
3
Laboratory of Theoretical Chemistry, Faculty of Chemistry and Biology, University of Santiago de Chile
(USACH), Zip 40, mail 33,
Faculty of Natural Sciences, Mathematics and Environment, Metropolitan Technological University, Av. José
Pedro Alessandri 1242,
CIMAT, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Zip 233, Santiago, CHILE.
Two theoretical proposals of how to rationalize a mechanism governing the charge transfer between
porphyrin derivatives metal complexes and substrates of small size are presented. One of them is
related to the identification of the local molecular region where the charge transfer has occurred.
This methodology was applied to the study of the hydrazine oxidation by a cobalt phthalocyanine
(tetrabenzoporphyrin)
and to the study of the chlorophenol oxidation by a nickel
tetrasulphophthalocyanine. The second propose identify the kind of charge transfer mechanism in
terms of the character of the donor acceptor hardness, electrostatic and orbital. The latter proposal
was applied to the nitric oxide oxidation by substituted nickel phthalocyanines and by substituted
copper phthalocyanines. All the calculations were performed at DFT level of theory.
Acknowledgements. The authors thank the financial support provided by FONDECYT Project Nº 1060203 and
FONDECYT Lineas Complementarias Project Nº 8010006. C.B. thanks to CONICYT by a Doctoral Fellowship and
a Terminal Thesis Fellowship.
18
Oral Lecture 3
Mauricio Fuentealba, María Teresa Garland
Laboratorio de Cristalografía, Departamento de Física, Facultad de Ciencias Físicas y Matemáticas.
Universidad de Chile.
The electrochemical response for the Zn(II) and Cu(II) bis(1-ferrrocenyl-1,3butanodionate)ethylenediimine complexes are similar, each exhibiting a two-electron reversible
oxidation
wave,
on
the
contrary,
Ni(II)
and
Co(II)
bis(1-ferrrocenyl-1,3butanodionate)ethylenediimine complexes undergoes two and three separated oxidation process,
respectively[1], insinuating that electronic communication is possible between the two ferrocenyl
groups through of an “inorganic bridge”.
These results prompted us to study the electronic and geometrical structures of these complexes
using density functional theory (DFT) calculations. These computational studies reveal that
following the order Zn(II)<Cu(II)<Ni(II)<Co(II) increase the contribution of the p- and d-orbitals of
the ligand and the metal, respectively, in the frontier molecular orbitals (MO) of the complexes. The
Figure shows the frontier MOs of the Ni(II) and Zn(II) ferrocenyl-diimine complexes.
Ni(II)
Zn(II)
Finally, the oxidized species has been also electronically explored by DFT calculations for a better
understanding of the different oxidation processes.
Acknowledgments. The authors thank the financial support from the Fondo Nacional de Desarrollo Científico y
Tecnológico, FONDECYT (Chile) Post-Doctoral Grant N° 3060043.
References:
[1] M. Fuentealba, Doctoral Thesis, P. Universidad Católica de Valparaíso, 2006.
19
Oral Lecture 4
Doris Guerraa, Rubicelia Vargasb and Jorge Garzab
a
b
Departamento de Ciencias Químicas, Facultad de Ecología y Recursos Naturales, Universidad Andrés Bello,
Av. República 275, Santiago, Chile.
Departamento de Química División de Ciencias Básicas e Ingeniería Universidad Autónoma MetropolitanaIztapalapa A.P. 55-534, México, Distrito Federal 09340, México
Pressure effects on the vertical excitation energy and on the Shanon entropy are reported for several
atoms (Mg, Ca, Sr, Ba, Ar, kr, Xe, Fe) and some of their ions. The vertical excitation energy is
computed by using the expressions derived by Galvan et al.[ J. Phys. Chem. A 102, 3134 (1998)],
where the vertical singlet-triplet gap is related with the spin potential, µ S+ . In the present
calculations, the atoms are confined by imposing Dirichlet’s boundary conditions on the KS
equations [Phys. Rev. E 58, 3949 (1998)] and the ground state electronic configuration is determined
for each confinement radius.
Acknowledgments. This work has received financial support from the Millennium Nucleus for Applied Quantum
Mechanics and Computational Chemistry, grant P02-004-F and Universidad Andrés Bello, grant UNAB-DI-0805/I.
20
Oral Lecture 5
Effect of Ni(II), Cu(II) and Zn(II) Association on the keto-enol
Tautomerism of Thymine
Elizabeth Rincón B.a, Otilia Mób, Alejandro Toro-Labbéa,1 and Manuel Yáñezb
a
b
QTC, Departamento de Química Física, Facultad de Química, Pontificia Universidad Católica de Chile,
Casilla 306, Correo 22, Santiago de Chile. [email protected]
Departamento de Química, C-9. Universidad Autónoma de Madrid. Cantoblanco, 28049-Madrid. Spain.
The effect of Ni(II), Cu(II) and Zn(II) association on the diketo/keto-enol tautomerism of thymine
has been investigated through the use of B3LYP density functional theory calculations. Final
energies were obtained at the B3LYP/6-311+G(2df,2p)//B3LYP/6-311+G(d,p) level of theory. All
the di-cations investigated lead to an oxidation of thymine and catalyze the tautomerization process,
this catalytic effect being much larger upon Ni2+ and Zn2+ association than upon Cu2+ association.
One of the most significant consequences of the base oxidation is that the calculated BDE’s are
primarily dictated by the value of the second ionization potential of the metal, and therefore follow
the sequence Cu2+ > Ni2+ > Zn2+ . Also importantly, metal dication association leads to a
stabilization of the keto-enol tautomer, which becomes the most stable form upon interaction with
Ni2+ and Zn2+ . This stabilization enhancement is the consequence of three concomitant factors,
namely, i) a stronger interaction of the metal cation with the carbonyl oxygen, ii) the interaction of
the metal with the dehydrogenated ring nitrogen, iii) an aromatization of the six-membered ring.
Acknowledgement: This work was supported by FONDECYT project N◦ 1060590. E.R. is grateful to the Facultad
de Química de la Pontificia Universidad Católica de Chile and MECESUP (PUC-0004, Red Química UCH-0116)
for a graduate fellowship.
21
Oral Lecture 6
Paula Jaramilloa, William Tiznadob, Patricia Pérezb,c.
a
b
c
Departamento de Ciencias Químicas, Facultad de Ecología y Recursos Naturales. Universidad Andrés Bello.
República 275, Santiago, Chile. [email protected]
Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653-Santiago, Chile.
Departamento de Química, Facultad de Ciencias, Universidad de Chile, Casilla 653-Santiago, Chile.
The origin of the α effect, i.e., the enhanced reactivity of nucleophiles that have an unshared electron
pairs on the atom adjacent to the nucleophilic center, relative to analogous species, has been a source
of continuous challenge since this phenomenon was brought to light by Edwards and Pearson.1 The
differential ground state (GS) destabilization, transition-state (TS) stabilization, product
stabilization, and solvent effects have been mentioned as possible reasons to account for the α-effect
phenomenon. The formation of a TS having aromatic character has been discussed as another
specific origin for this effect.2 Liebman and Pollack2 offered an explanation for the α-effect based on
the occurrence of an orbital interaction in the transition state, which is absent in both reactants and
products. The authors showed the presence of a cyclic transition state when the nucleophilic species
have α effect.2 In this work, we want to explain the formation of a cyclic transition structure in
systems involving the α-effect an its aromatic character. This work is complemented with the
Nucleus Independent Chemical Shifts (NICS)3 methodology, which has been used as aromaticity
criterion in transition states. Additionally, we have incorporated an electron localization function
(ELF)4,5 analysis, including into plane (σ) and out of plane (π) contributions. Although aromaticity
was initially thought for systems with π delocalized electrons, this methodology allowed to
rationalize properties of the system with σ-aromaticity. Hydrazine addition to a carbonyl group,
peroxide addition to benzonitrile and bisulfite addition to oximes have been used as benchmarks to
study this phenomenon. Up to now we have found cyclic transition states for these reactions and
analyzed both the acyclic transition state, and the aromatic character of these systems. This
treatment has been successful for explaining the enhanced of nucleophilicity of certain species and
also shows the importance of the transition state stabilization on the α-effect.
References
1. Edwards. J. O, Pearson. R. G. J. Am. Chem. Soc. (1962) 84,16.
2. Liebman. J. F, Pollack. R. M. J. Org. Chem. (1973) 38, 3444.
3. Chen. Z, Wannere. C. S. Corminboeuf. C. Puchta. R. Schleyer. Chem Rev. (2005) 105, 3842
4. Becke. A. D, Edgecombe. K. E. J. Chem. Phys. (1990) 92, 5397
5. Santos. J. C, Andrés. J, Aizman. A, P. Fuentealba. J. Chem. Theo. Comput. (2005) 1, 83.
Acknowledgments. This work has been supported by Fondecyt grant No. 1060961, the Millennium Nucleus for
Applied Quantum Mechanics and Computational Chemistry (Mideplan-Conicyt, Chile), grant P02-004-F and
DI-17-04 from Universidad Andrés Bello.
22
Oral Lecture 7
Theoretical Study on the Electronic Spectrum of Bi- and Tri-nuclear
Pt(II)-Au(I), Pt(II)-Ag(I), Pt(II)-Pt(II) and Pt(II)-Pd/II) Complexes
Fernando Mendizábal
Departamento de Química, Facultad de Ciencias, Universidad de Chile, Casilla 653- Santiago, Chile.
[email protected]; Fax: + 56 2 271 3888.
The
electronic
structure
and
the
spectroscopic
properties
of
[Pt(NH3)4][Au(CN)2]2,
[Pt(NH3)4][Ag(CN)2]2, [Pt(CNCH3)4][Pt(CN)4] and [Pt(CNCH3)4][Pd(CN)4] were studied at the HF,
MP2 and B3LYP levels. The absorption spectrums of these complexes were calculated by single
excitation time-dependent (TD) method at HF and B3LYP levels.
1
All complexes shown a
(dσ* → pσ) transition associated with a metal-metal charge transfer strongly interrelated with the
metal-metal distance. The values obtained theoretically are in agreement with experimental range.
Acknowledgements. This work has been supported by Fondecyt 1060044 and Millennium Nucleus of Applied
Quantum Mechanics and Computational Chemistry (MIDEPLAN) P02-004-F.
23
Oral Lecture 8
Carmen Herrera S.
Departamento de Ingeniería Química,Universidad Tecnológica Metropolitana
Ricardo Letelier D.
Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas Universidad
de Chile, Casilla 2777, Santiago, Chile. [email protected]
The electron distribution profile of electronic levels and some electronic properties, such as
the gap Homo-Lumo, is analyzed for some model molecular wires consisting of a donor and an
acceptor joined by either a linear chain of atoms or a stilbenoid group. In this model, the
valence electrons move in a model potential constructed by combining atomic spherical
electronic potential energy boxes and the Schrödinger is solved.
B
S18
S16
D
A
S17
S11
S15
S2
S12
C
S14
E
S4
S31
F
S5
S32
S13
The model potential representation of a molecule
The effect of some asymmetric crystal vibrations on the flow of electrons and their density
distribution profiles as well as the type of model potential describing the donor and acceptor, are
also analyzed for these model molecular wires. The concept of “molecular electric resistance” is also
analyzed under this model.
Acknowledgments. This work has been funded by CONICYT- FONDECYT, Chile, Grant N°1040923. Support from
the Milenium Nucleus for Applied Quantum Mechanics, contract N° P02–004-F is also gratefully acknowledged.
24
Oral Lecture 9
Mauricio Barrera
Facultad de Química, Pontificia Universidad Católica de Chile, Casilla 306, Santiago Chile
In a recent paper[1] we showed that within the Kohn-Sham(KS) framework, if the chemical potential is fixed
at the frontier eigenvalue, µ = εF it is possible to found a point, rµ in the radial mesh satisfying ,
µ= Veff (rµ)
(1)
where Veff is the Kohn-Sham effective potential solving the one electron KS equations. The rµ point show to
correspond with the experimental crystalline ionic radii of single anions.
Hardness is the resistance to change of the chemical potential when the electronic charge is added or released
from the atom and it is formally defined by
2η = δµ/δN
(2)
By decomposing the KS potential in four terms with known expressions as
Veff (r) = Vel(r) + VxLDA(r) + VxGGC(r) + Vc(r)
it is possible to take the derivative of each one of this term respect to the occupation number and discarding
the contribution of the derivative coming from the correctives terms (VxGGC and Vc), we obtain, at rµ ,
2η = δ Veff (rµ) = ∫Φi2(r)dr - cx Φi2(rµ)
δN
⏐r- rµ⏐
+ O(h
2
)
(3)
3 ρ (rµ)
2/3
Which is similar to the expression obtained previously by Parr and Co-workers for neutral atoms. [2]
Another possibility of determining the hardness of an anion is on employing the finite difference method
assuming that anion reacts as donor specie losing charge then,
2η− = ∆µ = lim εF(-1+δ) - εF(-1)
∆N
δ→1
(4)
δ
where the limit its taken in the vicinity of the neutral atom[3] avoiding the discontinuity occurring on going
from one shell to another. Equations (3) and (4) are examined for a series of single monatomic negative ions
with three different exchange potentials.
RESULTS
On Table 1 are displayed the resulting values for a series of nonoatomic anions employing the LB94
exchange potential on a modified Desclaux atomic program.
Table 1
−
Anion
η (eV)
δ Veff (rµ)/δN
rµ (A)
F6.82
6.46
1.01
Cl4.68
4.37
1.47
Br4.31
3.99
1.61
Na
2.45
2.15
2.60
O5.87
5.37
1.18
S4.17
3.71
1.66
References
[1] M.Barrera and F.Zuloaga Int. J. of Quantum Chem, 2044,106,(2006)
[2] M. Harbola, R. Parr and C. Lee, J.Chem Phys. 6055, 94, (1991)
[3] C. Goycolea, M.Barrera and F.Zuloaga, Int. J. of Quantum Chem, 455, 36, (1989)
25
Oral Lecture 10
Fe adatoms along Bi nanolines on H/Si(001): Patterning atomic
magnetic chains
Walter Orellana
Departamento de Física, Facultad de Ciencias, Universidad de Chile
Self-organized nanoestructures on surfaces have attracted much attention during the last few years
owing their promising applications in the patterning of low-dimensional magnetic systems. Indeed,
suitable epitaxial techniques make possible to build one-dimensional (1D) arrays of 3d magnetic
atoms adsorbed on step-edges of vicinal metallic surfaces. One of the best-studied magnetic systems
of this class are Co nanowires on Pt(997). Following this idea, we study the possibility to construct
monoatomic lines of Fe adatoms by decoration of the Bi-dimer line structure on H/Si(001), using
spin-density functional calculations. This Bi-line structure is obtained by Bi deposition on Si(001)
above the desorption temperature of 500 oC and consist of two parallel Bi-dimer lines which are
about 0.6 nm apart and can be over 500 nm in length [1]. Additionally, their structure are free of
defects and kinks and have a remarkable straightness. However, possible template applications
require the hydrogen exposure of the Bi-line/Si(001) sustrate. After hydrogenation, the H atoms only
terminate the Si atoms, leaving the Bi-dimer lines clean and preserving their 1D structure [2].
We investigate the stability of six adsorption sites for the Fe atom in the neighborhood of the Bi lines
formed on hydrogenated Si(001) surface. We find that the Fe atoms have the most-stable adsoption
sites beside the Bi-dimer lines, suggesting that they form quite 1D atomic arrays. The Fe 1D array,
which has a Fe-Fe distance of about 0.8 nm, is magnetic where Fe adatoms couple
antiferromagnetically with a weak exchange constant of about 14 meV. We also find that the
structural anisotropy of the Fe-adatom site induces a magnetic anisotropy which would be originated
in local magnetic dipolar interactions. We estimate a lower limit for the magnetic anisotropy energy
(MAE) which is the energy involved in rotating the magnetization from a direction of low energy
toward one of high energy. We find a very large MAE of about 3 meV/atom, suggesting a relative
high energy barrier to change the magnetization from the preferential directions. Concerning the
electronic properties, the 1D Fe array shows a magnetic half-metal behavior, i.e., the majority-spin
electrons are semiconducting and the minority-spin electrons are metallic [3]. The above results
show that the 1D Fe array adsorbed beside the Bi nanoline structure is a very interesting system both
for basic research and for possible technological applications, for instance, in spintronic and in
nanoscale data-storage devices.
[1] M. Naitoh, et al., Jpn. J. Appl. Phys., Part 1 39, 2793 (1999).
[2] R.H. Miwa, et al., Nanotechnology 16, 2427 (2005).
[3] W. Orellana, R.H. Miwa, Appl. Phys. Lett. in press (cond-mat/0606707).
26
Oral Lecture 11
Verónica Jiménez and Joel B. Alderete
Organic Chemistry Department, Universidad de Concepción, Casilla 160-C, Concepción, Chile
Procrustes Analysis is a method for relating two sets of multivariate observations, X and Y, by
finding the optimal transformations (rotation, reflection, translation and scaling) that provide the
best matching between the points in X and Y, preserving their internal object configuration.
In this work, we describe the use of Extended Ortogonal Procrustes Analysis (EOP) in the study of
geometrical similarity effects on chemical phenomena. EOP’s purpose is to find the optimal
orthogonal rotations and translations that give the best geometrical matching between two molecular
systems, represented by their standard 3D-coordinate matrices X and Y. The best match is defined as
the one which minimizes the sum of squared distances between the transformed X and the
corresponding target configuration given by Y:
min T ,t || Y − ( XT + jt T ) ||
subject to
T T T = TT T = I
(1)
where j T = [1 1 1...] (1× p ) is a unitary vector, t T is a (1×3) translation vector and T is a (3×3) rotation
matrix. Here we have assumed that X and Y have the same number of rows, p. If this condition is
not met one can add the required number of columns, with zeros as entries, to the smaller data set.
By solving equation (1) t and T can be expressed as:
t = ( B − AT ) T
j
p
T = VW T
and
where V and W arise from singular value decomposition of X T ( I −
(2)
jj T
)Y
p
EOP has been implemented in MATLAB 7.0 language and employed in the analysis of structural
similarity effects on the antitumor activity of 43 epothilone analogues (Figure 1). The optimized
structures of these molecules were obtained from computational calculations at B3LYP/6311++g(d,p) level and were employed in the EOP. It was found that geometrical similarity plays an
important role in determining the antitumor activity of the selected set of compounds.
R
O
X
HO
N
O
O
OH
O
Figure 1. Shematic representation of epothilone analogues
References.
1. P.M. Kroonenberg, W.J. Sunn, J.J.F. Commandeur, J. Chem. Inf. Comput. Sci. 43, 2025 (2003)
2. K.C. Nikolau, F. Roschangar, D. Vourloumis, Angew. Chem. Int. Ed. 36, 2014 (1998)
27
Oral Lecture 12
Simulación Molecular de la Interacción entre PIP2 y el canal TRPV1.
(Molecular simulation of the PIP2-TRPV1 channel interaction.)
Mascayano, C., González, W., Urbina, H. González-Nilo, F., Brauchi, S., Orta G., Raddatz N.,
y Latorre, R.
Centro de Bioinformática y Simulación Molecular, Universidad de Talca, Talca.
Centro de Estudios Científicos, Valdivia.
Las proteínas transmembranales son uno de los principales sistemas proteicos estudiados en al área
de la biofísica. En la actualidad hay escasa información estructural de este tipo de biomoléculas, sin
embargo dada la relevancia de este tipo de proteínas se hace necesario hacer esfuerzos teóricos que
permitan dilucidar las propiedades estructurales y dinámicas de estas moléculas. Así mismo, uno de
los grandes retos que presentan estos sistemas en química computacional, es el hecho que estas
simulaciones deben ser hechas en presencia de una bicapa lipídica, dado que sus propiedades
estructurales son altamente dependiente de la interacción proteína-lípido.
El objetivo de este trabajo es estudiar las propiedades estructurales de los canales de iones. Estos
canales pueden ser activados a través de diversos estímulos; tales como, cambios en el voltaje de
transmembranal, unión de ligandos o variaciones de temperatura. De estos eventos, nuestro interés
es explorar un mecanismo a través del cual PIP2 (fosfatidilinositol (4,5)-bifosfato) es capaz de
interactuar directamente con el canal TRPV1. Actualmente no existe información cristalográfica
para ningún canal del tipo TRP, sin embargo, hay evidencias experimentales que sustentan la
hipótesis de un putativo sitio de unión de PIP2 muy conservado en esta familia.
Como primera etapa de este estudio se generó un modelo molecular del canal TRPV1, que consta de
una región transmembranal y de un segmento C-terminal ubicado en la región intracelular. El
modelo inmerso en una capa lipídica de POPC fue relajado con dinámica molecular por 3 ns.
Para postular el sitio de unión de PIP2 en el canal TRPV1 utilizamos los métodos de simulación de
acoplamiento proteína-ligando (docking) implementado en el programa ICM. Para una mejor
evaluación de las interacciones electrostáticas, las cargas parciales de PIP2 fueron calculadas
utilizando métodos de mecánica cuántica (HF/6-31G**).
Los resultados de las simulaciones de docking muestran que PIP2 se ubica preferentemente entre
dos subunidades, la cola alifática de PIP2 se inserta en una cavidad entre los segmentos S4 y S5 y la
cabeza trifosforilada de PIP2 forma fuertes interacciones tipo puentes salinos con 3 residuos de
carga positiva de la región C-terminal, los cuales son clave y determinan la activación PIP2dependiente.
Agradecimientos. FONDECYT #1040254 (FGN) y #1030830 (RL).
28
Oral Lecture 13
Análisis Estructural del Poro del Canal de K+ HSLO a Través de
Simulaciones de Dinámica Molecular.
(STRUCTURAL ANALYSIS OF HSLO K+ CHANNEL PORE TROUGH MOLECULAR DYNAMICS SIMULATION)
González, W., Urbina, H., Vidal, M., Saavedra, G. y González-Nilo, F.
Centro de Bioinformática y Simulación Molecular (CBSM). Universidad de Talca
Las simulaciones de dinámica molecular (DM) consisten en calcular la posición de todos los átomos
del sistema en función del tiempo a través de la integración numérica de la ecuación de movimiento
de Newton, F = ma. El cálculo de una trayectoria clásica, provee información detallada acerca del
curso temporal de los movimientos atómicos, a lo cual es difícil acceder experimentalmente. Es por
ello que a través de DM nos propusimos estudiar la región del poro de los canales de potasio (K+)
dependientes de voltaje.
Los canales de K+ son proteínas transmembranales que facilitan el intercambio de este ión a través
de las células. Todos ellos presentan un motivo estructural muy conservado (GYGD), conocido
como el filtro de selectividad. En el canal KcsA, la mutación del residuo Asp80, presente en la
secuencia GYGD, produce canales no funcionales (Guidoni y col., 1999). Sin embargo, la misma
mutación en el canal hSlo (D292N) solamente reduce el paso de los iones K+ en un 40 % (Haug y
col., 2004). Al parecer el residuo Asp292 en el canal hSlo presenta un rol estructural diferente al
resto de los canales selectivos a K+. Para analizar este sistema se realizaron simulaciones de
dinámica molecular de 5 nanosegundos del canal hSlo, inserto en una membrana (POPE) bajo
condiciones periódicas de borde (modelo de agua TIP3P, 110 mM y 1 M de KCl). Estas
simulaciones nos permitieron determinar que el residuo Asp292 tiene un efecto modulador de la
concentración local de iones K+ en la región extracelular del canal.
La pregunta que nos hacemos es si la mutación D292N afecta solamente la concentración local de
iones en el vestíbulo extracelular o si además aumenta la energía libre de unión del K+ en el sitio S1
de unión del filtro de selectividad. Para responder esta pregunta, realizamos cálculos de perturbación
de energía libre a través del poro del canal usando Umbrella Sampling (Allen y col., 2006) en
simulaciones de DM en equilibrio.
Cálculos preliminares de Potential of Mean Force (PMF), usando la ecuación de Poisson-Bolzmann
nos indican que la mutación D292N en el canal hSlo, aumenta la energía de afinidad del K+ por el
sitio S1 de unión en el filtro de selectividad.
Agradecimientos: FONDECYT #1040254.
Bibliografía
Allen T.W., Andersen O.S., Roux B. (2006) Molecular dynamics - potential of mean force calculations as a tool
for understanding ion permeation and selectivity in narrow channels. In press.
Guidoni L., Torre V., Carloni P. (1999). Potassium and sodium binding to the outer mouth of the K+ channel.
Biochemistry 38:8599-8604.
Haug T., Olcese R., Toro L., Stefani E. (2004) Regulation of K+ flow by a ring of negative charges in the outer
pore of BKCa channels. Part II: Neutralization of aspartate 292 reduces long channel openings and gating
current slow component. J Gen Physiol. 124:185-197.
29
Oral Lecture 14
NMR and Molecular Modeling studies of cyclodextrin-catechin
complexes
Carolina Jullian1, Sebastián Miranda2, Gerald Zapata2, Teresita Orosteguis2 and Claudio
Olea-Azar2
1
2
Depto de Química Orgánica y Fisicoquímica. CEPEDEQ.
Depto de Química Inorgánica y Analítica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de
Chile. [email protected]
Cyclodextrin are cyclic glucose polymers in which glucopyranose units are bonded through α-(1,4)
linkages. The torus-like shape allows them to include guest molecules of appropriate polarity and
dimension due to their hydrophobic cavity and hydrophilic exterior surface. Complexation of guest
compounds with CDs can alter guest solubility, increase stability against the effects of light, heat,
and oxidation, mask unwanted physiological effects, and reduce volatility.
Tea is one of the most widely consumed beverages in the world; it has been used as a daily beverage
and crude medicine in China and Japan for thousands of years. The biological effects of green tea
are often attributed to the polyphenols, in particular, the catechins (CA). These tea catechins have
received considerable attention in recent years due to their diverse pharmacological potential, which
includes antimutagenic activity and anticarcinogenic effects. These properties could have
pharmaceutical applications. Inclusion in cyclodextrins is envisaged in order to mask the nasty
aspects (taste, color) of such phenolic compounds.
We describe now the results of our NMR investigation on the inclusion properties of catechin into βcyclodextrin (β-CD) and two derivatized cyclodextrins, Heptakis 2,6 di O β-cyclodextrin (2,6 DMβ-CD) and 2 Hidroxipropil-β-cyclodextrin (HP-β-CD) aimed to point out the factors affecting the
complexation selectivity and stabilization. Analysis of the proton shift change using the continuous
variation method confirm the formation of a 1:1 stoichiometric complex for catechin and the
different CDs in aqueous medium. The formations constant obtained by Diffusion-Ordered
Spectroscopy (DOSY) techniques indicated the following complex formation trend: β−CD > HP-βCD > 2,6 DM-β-CD. The detailed spatial configuration is proposed based on 2D NMR methods and
these results are compared with molecular modeling studies. The latter results are in good agreement
with the experimental data. There are two models between CA and CDs. CA with β-CD (A) forms a
complex where the B ring is orientated towards the primary rim; however when CD are derivatized
to HP-β-CD and 2,6 DM-β-CD (B), B ring of CA is orientated towards the secondary rim.
A
B
Acknowledgments. PG/57/205. University of Chile., Beca Memoria de Titulo de Pregrado, Facultad de
Ciencias Químicas Farmacéuticas Universidad de Chile, Proyecto Bicentenario de Inserción Académica
CONICYT 2005
30
POSTERS
31
Poster 1
A First Approximation for the Elucidation of the Inhibition of
Acetohydroxyacid synthase (AHAS) by Chlorimuron Ethyl
Gonzalo A. Jaña, Joel B. Alderete and Eduardo J. Delgado
Theoretical and Computational Chemistry Group, Faculty of Chemical Sciences, Universidad de Concepción.
Acetohydroxyacid synthase (AHAS), a ThDP dependent enzyme, is involved in the first common
step in the biosynthesis of branched chain amino acids (leucine, valine, isoleucine) in plants, fungi
and bacteria. Consequently, this enzyme is the target of several commercial herbicides, fungicides
and bactericides. These pesticides act inhibiting AHAS and therefore avoiding the synthesis of these
amino acids and consequently killing the organisms by lack in these essential amino acids.
The herbicides more commercially used are represented by the families of sulfonylureas and
imidazolinones because of their low toxicity in animals, high selectivity and low use rates. The
herbicides that inhibit AHAS bear no resemblance to the substrates and are not competitive
inhibitors, suggesting that they bind at a site distinct from the active site. Inhibition is a timedependent process. In addition the empirical evidence shows that the inhibition by sulfonylureas is
a time-dependent process. This leads to the suggestion that these chemicals react better with
enamine/α-carbanion reaction intermediate that is formed after decarboxylation of the first molecule
of pyruvate.
In this work we test the above hypothesis in the frame of computational quantum chemistry. To
achieve this goal we study in gas phase the reaction between the enamine/α-carbanion intermediate
and the herbicide Chlorimuron Ethyl, as well as the reaction between the intermediate and pyruvate,
in order to determine which one is more favored energetically. The calculations for both reactions
were carried out using the methodologies HF and DFT using the 6-31G (d,p) base. The search of the
transition state was carried out with the QST2 method, acronym of “quadratic synchronous transit.”
32
Poster 2
A Density Functional Theory Investigation of a Ferrocenyl Ketoamine
and Their Derivatives
Andrés Vegaa, Mauricio Fuentealbab, Carolina Manzurc, David Carrilloc.
a
b
c
Universidad Andrés Bello, Facultad de Ecología y Recursos Naturales, Av. República 275, Santiago.
Laboratorio de Cristalografía, Depto. de Física, Facultad de Ciencia Físicas y Matemáticas, Universidad de
Chile, Av. Blanco Encalada 2008, Santiago.
Laboratorio de Química Inorgánica, Instituto de Química, Pontificia Universidad Católica de Valparaíso, Av.
Brasil 2950, Valparaíso.
We report in this contribution the Density Functional Theory (DFT) investigations of ferrocenyl
compounds in order to obtain a better understanding of the structural and physical features of these
kinds of compounds.
X-ray diffraction structure (XRD) of the “half-unit” ligand Fc-C(O)-CH2-C(Me)=N-C6H4-o-NH2
only shows the ketoamine tautomeric form, 1a [1]. The DFT calculations confirm these observations
showing that 1a is 1.7 eV more stable than the ketoimine form 1b. However, in solution co-exist
both tautomeric forms: the 1a and 1b. On the other hand, the “half-unit” transforms into an
organometallic 1,5-benzodiazepinium 2+ [2]. The single crystal XRD studies are completely agree
with the calculations on 2+ showing a predominance of the delocalised diamine tautomeric form,
which is 0.8 and 0.7 eV more stable than the others two amine-imine tautomers. The deprotonation
of the molecule 2+ affords the ferrocenyl 1,5-benzodiazepine 3 [2]. In each case, the calculated
geometries are very similar to the structures determined by single crystal XRD studies.
H
N
NH
NH2
Fc
NH2
N
O
N
H
O
1a
Fc
N
Fc
1b
N
Fc
2+
3
Fc=Ferrocenyl
With these results in mind we explored the electronic structures of the compounds and its oxidized
and/or reduced forms (10/+, 20/+/2+ and 3-/0/+) in order to provide a rationalisation the redox potentials
of these compounds.
Acknowledgments. The authors thank the financial support from the Fondo Nacional de Desarrollo Científico y
Tecnológico, FONDECYT , Grant N° 1040851 (C.M. and D.C.) and Post-Doctoral Grant N° 3060043.
References:
[1] M. Fuentealba. Doctoral Thesis. 2006. Pontificia Universidad Católica de Valparaíso.
[2] M. Fuentealba, A. Trujillo, C. Gallardo, C. Manzur, D. Carrillo, A. Vega. Manuscript in preparation.
33
Poster 3
Design of Possibles Nicotinic Acetylcholine Receptor Ligands
Gerald Zapata-Torres1, Bruce K. Cassels2 y Edwin G. Pérez Hernández2
1
2
Departamento de Química Inorgánica y Analítica, Facultad de Ciencias Químicas y Farmacéuticas,
Laboratorio de Química Biodinámica, Facultad de Ciencias, Universidad de Chile.
Neuronal nicotinic acetylcholine receptors (nAChRs) are members of the “Cys-loop” family of
neurotransmitter-gated ion channels (LGICs). They are pentameric proteins formed by the
combination of several α2-α10 and β2-β4 subunits, gating cationic channels and playing a key role
in some neurological disorders.
Alkaloids such as 1 and 2 have been isolated from the bryozoo Flustra foliacea and they are
selective towards α4β2 and α7 nAChRs subtypes respectively.
H3C
10
N
4
Br
H
9
N
N
Br
3
6
CH3
H
8
5
N
2
1
7
H
1
2
The primary sequences of the different subunits were obtained from SWISSPROT database, and
sequence alignments were done using CLUSTALW. MODELLER was used to build threedimensional models for the amino-terminal domains of human α4β2 and α7 nAChRs subtypes
according to the homology protein modelling method and the crystal structure of the Acetylcholine
Binding Protein (AChBP) isolated from Lymnaea stagnalis was used as template. The optimization
of the ligand structures and the assignment of electrostatic charges were done using GAUSSIAN98.
Also, docking studies into human α4β2 and α7 nAChRs subtypes models were carried out using
derivatives of 1 and 2 with the program AUTODOCK, atomic solvation parameters were assigned
using ADDSOL tool, flexible torsions in the ligands were assigned with the AUTOTORS module
and the affinity grid fields were generated using AUTOGRID, all modules are included in the
AUTODOCK program package.
Forty different ligands were docked, where the structural variation was focussed into groups of
different size in positions 1 and 2, molecules with or without bromine atom, the type of substituent
on N-10 and also the length of the aminoalkyl chain.
Our results strongly suggest that the bromine atom and small groups in 2 position such as a propyl
group might be relevant for both selectivity and activity of these molecules.
Acknowledgements: Edwin G. Pérez Hernández is the recipient of a DAAD scholarship. Gerald Zapata-Torres
thanks to Proyecto Bicentenario de Inserción Académica CONICYT 2004.
34
Poster 4
ESR and theoretical of 5-nitroindazole derivatives as potential
antiparasitic drugs.
Jorge Rodríguez1,2, C. Olea-Azar1, M. González3, H. Cerecetto3 A. Gerpe3
1
2
3
Department of Inorganic and Analytical Chemistry. Faculty of Chemical and Pharmaceutical Sciences,
University of Chile, P.O. Box 233, Santiago 1, Chile
Department of Chemistry, Faculty of Basic Sciences, University Metropolitan of Sciences of Education,
Santiago, Chile.
Department of Organic Chemistry, Faculty of Sciences, University of the Republic, Montevideo, Uruguay
Key words: Nitroindazole, ESR, DFT
Nitrocompounds have found popular use in the treatment of parasitic infections because of their
antiprotozoal–antibacterial activity. In Latin America parasitic diseases represent a major health
problem. In particular Chagas’ disease (American Trypanosomiasis), caused by the protozoan
parasite Trypanosoma cruzi, affects approximately 20 million people from Southern California to
Argentina and Chile. Studies of nitrofuran families have been performed where the structural
differences caused the variation of some electronic properties like the reduction potential or the
hyperfine coupling constants.
Likewise density functional methods are known as capable of providing reasonable predictions for
ESR properties, the best results being obtained with the hybrid method B3LYP.
Nitro anion radicals generated by electrolytic reduction from a family of 5-nitroindazole derivatives
were analyzed using Electron Spin Resonance (ESR). DFT (hybrid method B3LYP) calculations
using 6-31G** basis set was performed to obtain the optimized geometries and spin distribution
respectively in order to assign the experimental coupling constants obtained with a simulation
program.
O
-
O
O R1
-
O
+
+
N
N
O
O
N
N
N
N
Y
R2
Y
R1 = H, CH3, CH2Ph
R2 = alinfatic amine
cyclic amine
Y = O, CH2
Acknowledgments. FONDECYT 1030949, MECESUP UMC-0204, RED RTPD NETWORK
35
Poster 5
Experimental and theoretical study of N-alkylation of nitroimidazoic
ring with alkyl halides
Constain H. Salamancaa and Paula Jaramillob
a
b
Departamento de Química, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, casilla 653,
Santiago de Chile, CHILE. [email protected]
República 275, Santiago, Chile.
N-substituted imidazoles exhibit a variety of valuable pharmacological properties such as
antiparasitic, antifungal and antimicrobial activity. In this work we have realized a experimental and
theoretical study of N-alkylation of nitroimidazoic ring with alkyl halides. N-alkyl-2-methyl-4nitroimidazoles were obtained by reaction of 2-methyl-5-nitroimidazole with different alkylhalides
in alkaline media, at reflux temperature, and acetonitrile like reaction solvent. All reactions were
carried out in presence of tetrabutylammonium bromide (TBAB) 3%, as phase transfer catalyst (see
Scheme)1.
CH3
N
CH3
NH + CH3(CH2)nX
BTAB
K2CO3
N
N
(CH2)n
CH3
CH3CN
NO2
O2 N
In all reactions N-alkyl-2-methyl-4-nitroimidazole was obtained as a major product. This reaction
proceed through a tautomeric equilibrium, which generates two nucleophilic sites. The nucleophilic
reactivity of these two sites, to the attack by alkyl halides, was calculated by using the local
reactivity index2, given by the Fukui function, philicity index, softness, electrostatic potential3 and
analysis of charge in the nitroimidazolic ring. A theoretical reaction mechanism was obtained by
analyzing the variations of the shape of the surface potential energy. The results show a minor
difference in the local reactivity, nevertheless the path reactions exhibit significant differences in the
barrier energy, favoring one of the product. These results agree quite well with the experimental
data.
References
1. Khabnadideh. S, et al. Biorg. Med. Chem. Lett. (2003) 13 2863-2865
2. Parr. R. G, Yang. W. Density functional theory of atoms and molecules. Oxford science publications. 1989.
3. Jaramillo. P, et al. J. Phys. Chem. A. (2006) 110 8181-8187
Acknowledgments: C.H.S. acknowledges a Ph.D. fellowship from the Deutscher Akademischer
Austauschdienst-DAAD. This work has been supported by the Millennium Nucleus for Applied Quantum
Mechanics and Computational Chemistry (Mideplan-Conicyt, Chile), and DI-17-04 from Universidad Andrés
Bello
36
Poster 6
Studies of Chiral Recognition Properties by NMR of Novel Bridged
Thiourea Chiral Calix[4]arenes
Claudio Saitz, Carolina Jullian, Rodrigo Acevedo, Julio De La Fuente, Hernán Pessoa
Depto. Química Orgánica y Físico-Química, Facultad de Ciencias Químicas y Farmaceúticas, Universidad de
Chile, Casilla 233, Santiago 1, Chile. [email protected]
Chirality is a property that often determines the action and behavior of molecules. In nature, biomolecules exist in only one of the
possible enantiomeric forms, for example, L-amino acids and D-sugars. Natural living systems are composed of chiral biological
materials. Chiral discrimination is of particular importance and considerable consequence in the medical sciences, as often one
enantiomer is pharmaceutically active whereas the other may show adverse side effects. A historic example is the anti-emetic activity
of one enantiomer of thalidomide, while the other can cause fetal damage1. Synthetic chiral receptors have been prepared to mimic
key features of biological systems toward chiral recognition. They may have potential applications in preparation, separation, and
analysis of enantiomers.
Calixarenes are a class of macrocycles, generally made up by base-induced condensation of p-substituted phenols and formaldehyde.
They have been widely used in the last two decades due to their potential for forming host-guest complexes with numerous classes of
compounds in supramolecular chemistry (crown ethers, cyclodextrines, porphyrines, aminoacids, etc) 2. Chiral calixarenes also have
potential applications in chiral recognition. Chirality in calixarenes can be generated by either attaching chiral substituents at one of
the rims (lower or upper) or synthesizing “inheherently” chiral derivatives, in which the non planarity of the molecule is exploited.
The inherent chirality suffers severe limitations, due the difficulties met in the resolution of racemates; therefore, the former approach
appears to be preferable.
Calix[4]arene
4.5
4.0
3.5
3.0
2.5
2.0 ppm
7
t-Bu t-Bu
t-Bu
t-Bu
3.5
3.0
2.5
4
2.0 ppm
OME
OH
OH
NH HN
S
NH HN
4.0
3.5
3.0
2.5
R2
OME
6'
Me
3'
Me
OMe
O
S
R1
R3
4.5
N
MeO
O
4.0
N
O
S CH2
Calix[4]arene-OME
4.5
H
N
R2
R1
R3
R1 = -CH2OH
R2 = -C6H5
R3 = H
2.0 ppm
Continuing the development of our research on asymmetric and symmetric calix[4]arenes3 , we recently have described the effective
synthesis of a variety of bis-thiourea bridged chiral calix[4]arenes bearing optically pure α,β-amino alcohol groups4. Here we report
that these calixarenes exhibit a good chiral recognition and as well as enantioselectivity between enantiomers of some drugs .eg.
omeprazole (OME). It is interesting to note that some 1H NMR signals of this racemic guest were split into two groups when is mixed
with chiral calixarene in CDCl3: both methyl groups (2.15 and 2.25 ppm) and one methoxyl group at 3.65 ppm. The results of DOSY
experiment (Diffusion Ordered SpectroscopY, is the measure of diffusion coefficients by NMR), which we inform herein, allowed us
to confirm the complex formation. The method has been developed in order to facilitate the complexe mixture analysis without
physical separation. Through these studies we can conclude that a 76 % of OME is included in the calixarene.
We thank FONDECYT (Grant 1050795)
1.2.3.4.-
Seeber G., Tiedemann B.E.F., Raymond K.N., Top.Curr.Chem, 2006 ,Gutsche C. David,
a) "Calixarenes Revisited"(Ed. Stoddart J.F.), Royal Society of Chemistry, Cambridge, England, 1998. b) “Calixarenes
2001”; Asfari Z.,Böhmer V., Harrowfield M. McB, Vicens J. Eds., Kluwer Academic: Dordrecht, 2001.
a) Santoyo F., Torres A. and Saitz C.,Eur. J. Org. Chem., 2000.3587 b) Leyton P, Sanchez-Cortes S, Garcia-Ramos JV,
Domingo C, Campos-Vallette M, Saitz C, Clavijo RE, J. Phys.Chem. B, 2004, 108, 17484. c) Leyton P., Sánchez-Cortes S.,
Campos-Vallete M., Domingo C., García-Ramos J.V., Saitz C., Applied Spectroscopy, 59 (8) 1009-1015, 2005
Saitz C., Jullian C. , Acevedo R.,.De La Fuente J, Pessoa H., Abs.11th BMOS, Canela, Brazil, August-Sept, 2005
37
Poster 7
[Cp*-Ru-Indacene-Ru-Cp*]+
Electronic Structure of a Mixed Valence Organometallic System
D. Mac-Leod Carey1, J. David2, A. Muñoz1, F. Burgos3, I. Chávez1, J. M. Manríquez1 and
R. Arratia-Pérez2
1
2
3
Departamento de Química Inorgánica, Facultad de Química, Pontificia Universidad Católica de Chile,
Casilla 306, Santiago, Chile.
Departamento de Ciencias Químicas, Universidad Andrés Bello, República 275, Santiago, Chile.
Instituto de Química, Facultad de Ciencias, Universidad Austral de Chile, Avda. Los Robles s/n, Campus Isla
Teja, Casilla 567, Valdivia. Chile.
Keywords: Mixed Valence System, Metallocenes, Material properties, .
Our research group has centered its attention in organometallic complexes with improved material
properties. One of the topics is the research and develop of an organometallic binuclear system that
possesses electronic communication between these metallic centers, in other words, a Mixed
Valence System, used as a model for a conductor organometallic polymer which probably will be
used as a nanowire. Despites already exists several Mixed Valence binuclear organometallic
systems, the basis in the electronic properties that allows the intermetallic communication is not yet
a completely understood field. This work is a first approach for a more deeply accomplished
computational study in this area. Now we feature the relationship of experimental data with
computational results obtained with the Amsterdam Density Functional package (ADF).
Acknowledgements: FONDECYT-Chile 1060589, 1030148; UNAB-DI 12-04; UNAB-DI 20-04; DID-UACH S-2006-45; Núcleo
Milenio P02-004-F; J. D. gratefully UNAB Doctoral Fellowship D. M. gratefully CONICYT-Chile Doctoral Fellowships and Facultad
de Recursos Naturales UNAB.
38
Poster 8
Effect of Peripheral or Non Peripheral Substitution Upon The
Spectroscopic Properties of Zinc Phthalocyanine.
D. Mac-Leod Carey1, E. Alarcón2, A. M. Edwards2, A. M. García2, J. M. Manríquez1 and
R. Arratia-Pérez3.
1
2
3
Departamento de Química Biológica, Facultad de Química, Pontificia Universidad Católica de Chile, Casilla
306, Santiago, Chile.
Keywords: Phthalocyanines, Peripherical and Non Peripherical Substitution, Singlet Oxygen.
The present study introduces the effect of the peripheral and non peripheral octasubstitution in the
Zinc Phthalocyanine (ZnPc) employing as model hydroxylate´s ZnPc derivatives (ZnPcOH8-P and
ZnPcOH8-NP) and for comparison ZnPc without substitution. Our findings clearly indicate a
significative difference in the frontier orbitals (HOMO and LUMO) which reflect this distinction on
the electronic absortion spectra calculated by means of TD-DFT with Amsterdam Density
Functional package (ADF). On another note, the energy difference (GAP) between the first singlet
and the triplet excited states were calculated. This last fact, it would be related with the differences
observed in the quantum singlet oxygen yield for the substituted ZnPc’s.
0,02
ƒ
ZnPc
ZnPcOH8-P
ZnPcOH8-NP
.
0
300
400
500
600
700
800
900 nm
Acknowledgements: FONDECYT-Chile 1040667, 1060589, 1030148; UNAB-DI 12-04; Núcleo Milenio P02-004-F; D.
M. and E. A gratefully CONICYT-Chile Doctoral Fellowships and A. M. G. DIPUC and Facultad de Recursos
Naturales UNAB.
39
Poster 9
π Donor / Acceptor Effect on Lindqvist type Polyoxomolybdates
Functionalizated with Multiple-Bonding Nitrogeneous Ligands
D. Mac-Leod Carey1, A. Muñoz1, C. Bustos2, J. M. Manríquez1 and R. Arratia-Pérez3.
1
2
3
Instituto de Química, Facultad de Ciencias, Universidad Austral de Chile, Avda. Los Robles s/n, Campus Isla
Teja, Casilla 567, Valdivia. Chile.
Keywords: Polyoxomolybdates, Heteropolyanions, Functionalization, π donor, π acceptor.
Several Lindqvist type polyoxomolybdates [Mo6O19]2- have been synthesized by the replacement of
a terminal oxo ligands by multiple-bonding nitrogeneous ligands (process called functionalization),
such as, imido ArN2-, hydrazido ArAr’N22- (π donor), diazenido ArN22+ and nitrosyl NO+ (π
acceptor). This work deals about the structural, vibrational and electronic differences founded in
those functionalizated polyoxomolybdates. Results evidence huge differences between them, which
can be related to its π donor or π acceptor character. Those differences can be observed as much in
the orbital spatial representations, energy levels of molecular orbitals, structural bond lengths and
vibrational frequencies.
All the calculations were performed in the Amsterdam Density Functional package (ADF) with the
appropriated symmetry for each case, Oh for [Mo6O19]2-, C4v for [Mo6O18(NO)]3-, C2v for
[Mo6O18(NNArAr)]2- and [Mo6O18(NAr)]2- and Cs for [Mo6O18(NNAr)]3-.
Acknowledgements. FONDECYT-Chile 1060589, 1030148; UNAB-DI 12-04; DID-UACH S-2006-45; Núcleo Milenio
P02-004-F D. M. gratefully CONICYT-Chile Doctoral Fellowships and Facultad de Recursos Naturales UNAB.
40
Poster 10
Electrophilicity and spin polarization within the framework of spinpolarized density functional theory
Eduardo Chamorro(a) and Patricia Perez(b)
(a) Departamento de Ciencias Químicas, Facultad de Ecología y Recursos Naturales. Universidad Andrés Bello
Av. República 275. Santiago, Chile. [email protected]
(b) Departamento de Química y Departamento de Fisica, Facultad de Ciencias.Universidad de Chile. Casilla
653-Santiago. Chile
The development and usefulness of both global and local descriptors of chemical reactivity based on
the spin-polarized density functional theory framework (SP-DFT) are discussed.1 In particular, we
have reviewed the applicability range of electrophilicity indices defined both at the global and local
levels.2 Both models have been applied to simple substituted carbenes and silylenes3,4 to examine
their reactivity patterns. An orbital implementation of the SP-DFT Fukui functions has been further
studied4 and the natural generalization toward topological-defined condensation schemes5 has been
further sketched.
Acknowledgements. This work has been supported by Fondecyt (Chile), grants 1030173 and 1060961, and the
Millennium Nucleus for Applied Quantum Mechanics and Computational Chemistry (Mideplan-Conicyt, Chile),
grant P02-004-F. We thank the Universidad Andres Bello (UNAB) by support through the Project UNAB-DI 16-04.
References
1
2
3
4
5
R. Vargas, A. Cedillo, J. Garza, and M. Galvan, Reviews of Modern Quantum Chemistry 2, 936 (2002)
E Chamorro, P Pérez, F De Proft, P Geerlings. Journal of Chemical Physics 124 (2006) 044105.
E. Chamorro, J. C. Santos, C. Escobar, P.Perez, Chemical Physics Letters, (2006, In Press).
E Chamorro, P Pérez. Journal of Chemical Physics 123 (2005) 114107.
F. A. Bulat, E. Chamorro, P. Fuentealba, and A. Toro-Labbe, Journal of Physical Chemistry A 108 (2), 342
(2004); E. Chamorro, W. Tiznado, C. Cardenas, M. Duque, J. C. santos, P. Fuentealba, J. Chem. Sci. 117, 419
(2005).
41
Poster 11
2D-ROESY NMR Studies and Molecular Modeling of Supramolecular
Complexes of αCD-DIALKYLAMINES
Erika Lang1, Nicolas Yutronic2, Juan Merchán2, Paul Jara2 and Gerald Zapata-Torres3
1
2
3
Centro de Equipamiento Mayor, Departamento de Biología, Facultad de Ciencias, Universidad de Chile.
Laboratorio de Síntesis Inorgánica y Electroquímica, Facultad de Ciencias, Universidad de Chile.
Departamento de Química Inorgánica y Analítica, Facultad de Ciencias Químicas y Farmacéuticas,
Cyclodextrins (CD) are cyclic no reducing sugar consisting of six or more glucopyranose units compressing an inner
hydrophobic cavity and outer hydrophilic surface. Because of its hydrophobic character, water molecules that occupy
the CD cavity can be readily replaced by less polar guest molecules forming host-guest inclusion complex. CD comprise
a family if three well-known industrially produced major, and several rare, minor cyclic oligosaccharides. The most
common CD are designated with the prefix α, β and γ corresponding to six, seven and eight glucopyranose units, the
cavity diameter and therefore the number and type of guests that can be accommodated varies with the number of
glucopyranose units that comprise the CD molecule. The guest molecule is limited in its size to be enclosed within the
isolated cavity. Most guest molecules form a 1:1 inclusion complex, however, more complicated complex such as 2:1,
1:2 and 2:2 are possible.
Supramolecular chemistry is that discipline of chemistry which involves all intermolecular interactions where covalent
bonds are not established between the interacting species. The majority of these interactions are of the host-guest type.
Among all potential hosts, the CD seem to be the most important ones.
2D-ROESY spectrum showed strong intermolecular NOE cross-peaks between the DOA protons Hβ−γ−δ−ε−ζ, and Hη with
both protons H3 and H5 in the interior wall of the CD cavity (Figure 1), 2D-ROESY experiments allowed to observe the
5 Å spatial proximity limit among the functional group of guests and α-CD. The proton Hη of the guest that corresponds
to the methyl group presents two strong interactions with the protons H3 and H5, and also it presents two weak
interactions with the protons H4 and H2 of the host, thus indicating that the spatial proximity of the strongest interactions
is minor, effect that turns out to be also reflected in the ROESY of other compounds of inclusion (α-CD:DPA and αCD:DHA). These results indicate that the methyl groups of the guests (DPA, DHA and DOA) find themselves located
inside the cavity of the CD.
Our molecular modeling studies carried out for all the host-guest complexes have shown unequivocally that all
alkylamines (DPA, DHA and DOA ) under study are contained in the interior of the cavity, where the methyl groups
interact with protons H-3 and H-5 of the sugar moieties and the methylenes interactions are also represented.
Figure 1
Acknowledgments. Gerald Zapata thanks to Proyecto Bicentenario de Inserción Académica CONICYT 2004.
Paul Jara thanks to FONDECYT grant N° 1040581. Nicolas Yutronic thanks to FONDECYT grant N° 1050287. Erika
Lang thanks to Laboratorio de Resonancia Magnética, USACH.
42
Poster 12
Theoretical Study in [C2H4-Tl]n+ and [C2H2-Tl]n+ (n = 2, 3) Complexes
Fernando Mendizábal and Daniela Donoso
Departamento de Química, Facultad de Ciencias, Universidad de Chile, Casilla 653- Santiago, Chile.
[email protected]; Fax: + 56 2 271 3888.
We studied the attraction between [C2H4] or [C2H2] and Tl(I) in the hypothetical [C2Hm-Tl]n+
complexes (m = 2 or 4, n = 2,3) using ab initio methodology. We found that the changes around the
equilibrium distance C-Tl and in the interaction energies are sensitive to the electron correlation
potential. We evaluated these effects using several levels of theory, including HF, MP2, MP4 and
CCSD(T). The obtained interaction energies differences at the equilibrium distance Re (C-Tl) range
from 25 and 50 kJ/mol at the different levels used. These results indicated that the interaction
between olefinic systems and Tl(I) are a real minimum on the potential energy surfaces. We can
predict that these new complexes are viable of synthesizing.
Acknowledgements: This work has been supported by Fondecyt 1060044 and Millennium Nucleus of Applied
Quantum Mechanics and Computational Chemistry (MIDEPLAN) P02-004-F.
43
Poster 13
Molecular Modeling of 5-HT2 receptors
Jorge Rodríguez1,2, Gerald Zapata-Torres2
1
2
Department of Inorganic and Analytical Chemistry. Faculty of Chemical and Pharmaceutical Sciences,
University of Chile, P.O. Box 233, Santiago, Chile
Department of Chemistry, Faculty of Basic Sciences, University Metropolitan of Sciences of Education,
Santiago, Chile.
Keywords: Molecular Modelling, Membrane Proteins, 5-HT2, Docking
Explicit 3-D structural models for the transmembrane domain based on Bovine Rhodopsin structure
(bovine rhodopsin P02269) were built using MODELLER program for human 5-HT2A and 5HT2C
serotonin receptors. This methodology considers the superposition of the regions aligned, to avoid
steric collisions, the stereochemistry of the model and most favourable rotamers for aminoacid side
chains. Finally, these models were used to assess likely binding modes of their endogenous ligand 5HT and phenyalkylamines such as DOB, DOF, DMA, QDOB and other N sustituded α-desmethyl
DOB analogs.
The energy analysis of the minimised structures obtained by ligand docking showed a good
agreement with the affinity constants obtained from experimental results and described in the
literature. The most important interaction is the electrostatic interaction between the ammonium
group of the ligands and the Asp70/70 residue of the 5-HT2A or 5-HT2C receptor. Other residues that
interact with the ligands also show a good agreement with experimental data for both receptor
subtypes. It should be recalled that both 5-HT2 receptor subtypes considered here have conserved
residues at corresponding positions in their sequences but, in spite of this, the contribution of each of
these to the total interaction energy is different. The ability to identify residues involved in ligand
binding in our models 5-HT receptor ligands reinforces the idea that the complexes formed between
these ligand types and the receptors occupy similar regions in both receptor models.
Acknowledgments. JR thanks to MECESUP PROYECTO UMC-0204 and GZT thanks to PROYECTO BICENTENARIO
DE INSERCION ACADEMICA CONICTY 2005.
44
Poster 14
Molecular modeling study on the interaction of Fe65 PTB2 Domain and
AICD complex
Sebastian Miranda-Rojas1, Claudio Olea-Azar1, Gerald Zapata-Torres1 and Daniel BorquezMacherone2
1Department of Inorganic and Analytical Chemistry, Faculty of Chemical and Pharmaceutical Sciences. Olivos
1007. University of Chile.
2Department of Biology, Faculty of Sciences. Las Palmeras 3425, Ñuñoa. University of Chile.
APP is an integral membrane glycoprotein. Its principal isoform consists of 695 amino acids (aa)
which are distributed in an extracellular domain, a transmembrane region and small cytoplasmatic
tail of approximately 60 aa.
Currently its function is unknown, but it has been implicated in Alzheimer disease, since due to its
consecutive proteolitic cleavages of the transmembrane domain by β and γ secretases generates the
β amyloid peptide, where its extracellular accumulation results on the formation of amyloid plaques
found in Alzheimer’s patients brain. However, nowadays attention have been paid to the possible rol
that the intracellular domain of APP (AICD) plays in intracellular signaling processes, where it
activates the transcriptional activity of several proteins and the proteolityc processing of APP. One
of the most important complexes that AICD forms is the complex with the Fe65 adaptor protein,
which in turn consists of three domains namely WW, and the phophotyrosine binding domains PTB1 and PTB-2. So far, AICD is the only peptide described that interacts with PTB-2 Domain, which is
located near the end of the C-terminal region of this protein. This interaction is the main
transcriptional activation mechanism of Fe65 which is directly related with the increase of β
amyloid peptide present in Alzheimer’s brain patient.
The understanding of the molecular mechanisms
involved in Alzheimer’s disease is of great deal,
moreover the lack of a crystal structure of both
interaction domains, makes it difficult to address the
problem, so we have carried out molecular modeling
studies in order to get an accurate description of the
PTB2-AICD interaction (Figure 1). This study could
lead us to a better understanding of the molecular
basis for the selectivity and protein-protein
recognition that PTB2 shows towards AICD
(considering a fragment of 10 aa described in
literature as involved in that interaction). From our
point of view, the inhibition of this interaction is an important goal to achieve and a pharmaceutical
target to fight Alzheimer’s disease.
Acknowledgments. Sebastián Miranda-Rojas thanks to Beca de Memoria de Título de Pregado, Facultad de
Ciencias Químicas y Farmacéuticas and Gerald Zapata-Torres thanks to Proyecto Bicentenario de Inserción
Académica CONICYT 2005.
45
Poster 15
Prediction of Octanol-Water Partition Coefficients of Chlorinated
Biphenyls by Molecular Descriptors.
Gerardo A. Diaz, Gonzalo A. Jaña and Eduardo J. Delgado
Theoretical and Computational Chemistry Group, Faculty of Chemical Sciences, Universidad de Concepción.
The behavior of xenobiotics (man-made chemicals) in the environment is largely controlled by their
relative tendencies to partition into air, water, and organic phases such as lipids, waxes, and natural
organic water. Accordingly, one of the key descriptors of these tendencies is the octanol-water
partition coefficient (KOW). Moreover, the importance of octanol-water partition coefficients as an
indicator of lipophilicity in biological and medical sciences is well known. Since the pioneering
work by Hansch, the need for accurate and fast calculation of its value for new molecules has been
recognized.
Polychlorinated biphenyls (PCBs), a family of 209 congeners each of which consists of two benzene
rings and one to ten chlorine atoms, are ubiquitous in the global environment because of their
biological and chemical stability and their historical widespread use in the power generation
industry.
In this contribution, a quantitative structure-property relationship (QSPR) model based on molecular
descriptors is reported for the prediction of logarithm of octanol-water partition coefficient of
PCBs. The data set contains 92 compounds covering a log KOW range from about 4.5 to 9.1 log
units.
46
Poster 16
Nucleophilic Activation Of Charged Systems: Carbon Nanotube v/s
Dielectric Models
German Miño1, Willian Tiznado2 and Renato Contreras2
1
2
Departamento de Ciencias Químicas, Facultad de Ecología y Recursos Naturales, Universidad Andrés Bello
Departamento de Quimica, Facultad de Ciencias, Universidad de Chile
Nucleophilic activation was evaluated for a series of charged H-bonded species based on an
empirical spectroscopic scale [1]. The behavior in different environments was analyzed for the
anionic complexes [FHCL]- , [FHBr]- & [FHI]- at B3LYP/DGDZVP level of theory. Encapsulation
inside capped carbon nanotubes (CCNT) and within a dielectric were performed using ONIOM and
SCIPMC tehcniques. All calculations were done with Gaussian package of software version 2003.
Our result shows that there exist a significant nucleophilic activation, with respect to the gas phase,
for complexes encapsulated in CCNT´s, and that this enhancement can not be reproduced by
dielectric models.
References:
1.- Campodónico, P; Aizman, A & Contreras, R. Empirical scale of nucleophilicity for substituted
pyridines. Chem. Phys. Lett. 422, 206 (2006).
47
Poster 17
Theoretical Study on CDK2 Inhibitors Using a Global Softness Obtained
from the Density of States
Jans H. Alzate-Moralesa,*, William Tiznadoa, Juan C. Santosb, Carlos Cárdenasb,
Renato Contrerasa
a
b
Departamento de Química, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile
Av. República 275, Piso 3, Santiago, Chile
We report a theoretical study on a series of CDK2 inhibitors using a set of global reactivity indexes
defined in terms of the density of states. The statistical analysis was performed on the basis of two
groups of 11 and 6 compounds respectively, reported by Hardcastle et al [J. Med. Chem. 2004, 47,
3710-3722] which were classified on the basis of the sites targeted within the active site of CDK2.
The comparison between the biological activity and the electronic chemical potential approached as
the Fermi level yields poor results, thereby suggesting that the interaction between the hinge region
(HR) of CDK2 and the ligands may have a marginal contribution from the charge transfer (CT)
component. Comparison between the biological activity and global softness shows a better
correlation, thereby suggesting that polarization effects outweigh the CT contribution in the HRligands interaction. The study is complemented with a local analysis based on the electrostatic
potential which gives a good qualitative description about the orientation that the ligands adopt upon
approaching the CDK2 hinge region, within a picture which is reminiscent to the lock and key
model.
-3
y = -4.1049x + 7.5903
R2 = 0.8026
-2.5
-2
LogIC50
-1.5
-1
-0.5
0
0.5
1
1.5
1.5
1.7
1.9
2.1
2.3
2.5
2.7
Global Softness (1/eV)
Acknowledgments. Work supported by the Millennium Nucleus for Applied Quantum Mechanics and Computational
Chemistry, Grant P02-004-F.
48
Poster 18
Study of aromaticity of planar carbon clusters through the topological
analysis of electron localization function
Leonor Alvarado y Juan C. Santos
Departamento de Ciencias Químicas, Facultad de Ecología y Recursos Naturales, Universidad Andrés Bello.
Av. República 275, Santiago, Chile. [email protected]
The annular structure of planar carbon cluster (C2n n=3-12) have been studied in the framework of
density functional theory using B3LYP/6-31g(d) theoretical level. The electron delocalization
(aromaticity) was evaluated through bifurcation analysis of electron localization function, ELF. We
evaluated the contributions of the sigma and pi electron systems applying the ELF analysis over the
respective separated densities, ELFσ and ELFπ.1,2
We have found that systems with 4C+2 (C=1-5) carbon atoms are aromatic, which is in agreement
with Xu et al.3 These clusters have a bifurcation of the π system like benzene, with a bifurcation
value close to 0.91. On the other hand, we have found that sigma delocalization has a high
contribution in these kind of clusters, increasing with the size of cluster from 0.735 (typical
interaction in a classical organic compounds) to 0.839 (high delocalization as in case of σ-aromatic
compound) for C6 and C22, respectively.
The system with 4C (C=2-6) carbon atoms show a typical conflicting delocalization. The sigma
interaction increases with the size of cluster yielding to a high delocalization from C16 to C24, while
the π system corresponding to antiaromatic compounds.
Acknowledgements. Millennium Nucleus for Applied Quantum Mechanics and Computational Chemistry, Nº
P02-004-F (Mideplan-Conicyt) and Dirección General de Investigación, Grant DI-22-05/R, UNAB.
References
1
J. C. Santos, W. Tiznado, R. Contreras and P. Fuentealba, J. Chem. Phys. 120, 4, 1670, 2004.
2
Juan C. Santos, Juan Andres, Arie Aizman, and Patricio Fuentealba, J. Chem. theory and comp., 1, 83, 2005
3
S. Xu, M. Zhang, Y. Zhao, B. Chen, J. Zhang, C. Sun, Chem. Phys. Lett. 421, 444, 2006
49
Poster 19
Calculated Relativistic Nuclear Magnetic Shieldings on monohalides of
noble metals
Jorge David, Doris Guerra, and Ramiro Arratia-Perez
República 275, Santiago-Chile. [email protected], [email protected], [email protected]
Keywords: Nuclear Magnetic Shieldings, Relativistic calculations, Monohalides of noble metals
Fully ab-initio relativistic and nonrelativistic calculations of the nuclear magnetic shielding of nine
63
107
197
19
35
79
127
Ag,
Au; X= F, Cl, Br,
I) are reported.
molecular compounds MX (M= Cu,
Relativistic calculations were performed with Dirac-Hartree-Fock level (DHF) in the Random-Phase
approximation method (RPA). The relativistic and nonrelativistic calculations of the Nuclear
Magnetic Resonance (NMR) shieldings are compared in order to establish its relationship with
nuclear charges and the effects of spin-orbit coupling in the NMR shielding constant.
50
Poster 20
Endo/Exo Selectivity in Intermolecular Diels-Alder Reactions
Jorge Soto-Delgado and Renato Contreras
Departamento de Química, Facultad de Ciencias, Universidad de Chile, Casilla 653-Stgo, Chile.
The potential energy surface for the intermolecular cycloadition of five-membered dienes to five
membered dienophiles have been fully explored at the B3LYP/6-31+G* level of theory. Transition
state structures have been located and characterized. The endo approach appears energetically
favored, in agreement with experimental results1. The energy analysis is reinforced by a theoretical
study introducing global and activation indexes.
Acknowledgments. Work supported by MECESUP-0408 fellowship and Fondecyt, Grant 1030548 and
Millennium Nucleus for Applied Quantum Mechanics and Computational Chemistry, Grant P02-004-F.
the
Reference:
1. Rulisek, L., Sebek, P., Hlavas, Z., Hrabal, R., Capek, P., Svatos. A.; J. Org. Chem, 2003, 70, 6298.
51
Poster 21
Humic Acids As Molecular Assemblers in Sers Detection of Polycyclic
Aromatic Hydrocarbons
J. S. Gómez-Jeria, M. M.Campos-Vallette and P. Leyton,
University of Chile, Faculty of Sciences, P.O. Box 653 Santiago, Chile. [email protected]
A humic acid (HA) of 103 kDa molecular weight was successfully used in surface-enhanced Raman
scattering SERS experiments as molecular occlusion assembler deposited onto a Ag colloidal
surface to detect the polycyclic aromatic hydrocarbons PAHs chrysene and pyrene. Chrysene (Chr)
and pyrene (Pyr) were detected at concentrations lower than 10-6 M by using the 541 nm excitation
laser line. A charge transfer between HA and the analyte characterizes the humic acid-analyte
interaction. The interaction resulted to be more significant in the case of the pyrene molecule.
Extended Hückel calculations based on a molecular model for the interacting Chr/HA/Ag system
support the experimental conclusions. The Chr-HA distance is about 3.5 Å and the most probable
orientation for Chr is plane parallel to the aromatic fragments of HA. An energy transfer from the
silver surface to HA and from the analyte to HA is concluded.
Acknowledgements. The authors acknowledge project Fondecyt 1040640 from Conicyt and project C-13879
from Fundación Andes. PL acknowledges project AT 4040084 from Conicyt.
References.
1. P. Leyton, J. S. Gómez-Jeria, S. Sanchez-Cortes, M. M. Campos-Vallette. J. Phys. Chem.. B110, 6470 (2006)
52
Poster 22
On The “Metallicity” of Some Metallic Nanotubes
Juan S. Gómez-Jeria1 and Ramiro Arratia-Pérez2.
1
2
Programa de Doctorado en Fisicoquímica Molecular. Facultad de Ecología y Recursos Naturales.
Universidad Andrés Bello, Santiago, Chile; and Departament of Chemistry, Faculty of Sciences, University of
Chile. P.O. Box 635, Santiago-Chile.
Facultad de Ecología y Recursos Naturales, Universidad Andrés Bello. Santiago, Chile.
Pure and perfectly cylindrical defect-free carbon NTs are viewed as a conformal mapping of the
two-dimensional honeycomb lattice of a single sheet of graphite onto the surface of a cylinder. The
helical symmetry of the carbon atoms around the axis of the cylinder is denoted by two integers
(m,n) that indicate the number of lattice vectors in the graphite plane used to make the nanotube. For
certain values of the couple (m,n) two sub-families of NTs are obtained. For m=n the so called
armchair family of NTs is generated. For the case (m,0) the zigzag family of NTs is formed. It is
accepted that a relationship exists between the values of the pair (m,n) and the conductivity
properties of perfectly cylindrical defect-free carbon NTs. If (n-m)=3t (with t=0,1,2...) the
corresponding NTs will display a metallic behaviour. Otherwise, the NTs will have semiconducting
properties. This means that all the zigzag and one third of the armchair NTs will be metallic. Lieber
et al. used low-temperature scanning tunneling microscopy to characterize the atomic structure and
local DOS of metallic zigzag and armchair single-walled carbon nanotubes (SWNTs) [1]. Their data
recorded on (9,0), (12,0) and (15,0) zigzag SWNTs show conclusively the existence of gap-like
structures at the Fermi energy, EF. Consequently, these metallic zigzag NTs are in fact small-gap
semiconductors. Their results also show that isolated armchair SWNTs have neither gaps or
pseudogaps.
We show here that employing Molecular Orbital theory at the Extended Hückel Theory level (EHT)
we may predict perfectly the experimental conducting properties of the (m,m) and (m,0) families of
isolated SWNTs. The size of the selected NTs were determined accordingly to the “minimal length”
rule [2]. The EHT Total Density of States curves for the semiconducting (10,0) zigzag NT, the
metallic (5,5) armchair NT and the small-gap semiconductor (9,0) zigzag NT were obtained and
plotted for the [-3 eV,3 eV] interval about the Fermi Level. The structure of each curve is in perfect
agreement with experimental results.
Acknowledgements. This research was partially funded by Department of Chemistry, Faculty of Sciences,
University of Chile.
References.
1. M. Ouyang, J-L. Huang, C. L. Cheung, C. M. Lieber, Science 292, 702 (2001).
2. J. S. Gómez-Jeria, F. Soto-Morales, J. Chil. Chem. Soc. 50, 597 (2005).
53
Poster 23
Carbon Nanotube as Molecular Assemblies: Surface-Enhanced
Resonance Raman Spectroscopy (SERRS) and Theoretical Studies
J. S. Gómez-Jeria, M. Campos-Vallette and P. Leyton.
Departament of Chemistry, Faculty of Sciences, University of Chile. P.O. Box 635, Santiago-Chile.
[email protected]
It has been demonstrated by SERRS experiments that metallic single-walled nanotubes can be used
as chemical assemblies between the pyrene analyte and the silver colloidal surface. Pyrene has been
detected at concentrations lower than 10-9 M by using the 541 nm excitation laser line. A charge
transfer from the surface to the nanotube characterizes the nanotube-silver surface interaction. The
pyrene-nanotube interaction occurs through a π-π electronic stacking. Extended Hückel calculations
based on a simplified molecular model for the analyte/nanotube/surface system support the
experimental conclusions. The nanotube-pyrene distance is 3.4 Å and the most probable orientation
for pyrene is confirmed to be plane parallel to the nanotube surface. An energy transfer from the
silver surface to the nanotube/analyte system is verified.
Acknowledgements. Authors acknowledge project Fondecyt 1040640 from Conicyt (Chile) and Fundación
Andes project C-13879 for financial support. P. Leyton acknowledges project AT 4040084 from Conicyt.
Reference.
P. Corio, S.D.M. Brown, A. Marucci, M. A. Pimenta, K. Kneipp, G. Dresselhaus,
M.S. Dresselhaus. Surface-enhanced resonant Raman spectroscopy of a Single-wall carbon
nanotubes adsorbed on silver and gold surfaces. Phys. Rev. B 61 (2000)13202.
54
Poster 24
Multiple Linear Regression Study of the Antimalarial Activity of
Aziridinyl 1,4-Naphthoquinonyl Sulfonate and Acylate Derivatives
M. Leonor Contreras
Laboratorio de Química Computacional, Departamento de Ciencias del Ambiente, Facultad de Química y
Biología, Universidad de Santiago de Chile, Casilla 40, Correo 33, Santiago, Chile. [email protected]
José Alvarez
Departamento de Ingeniería Informática, Facultad de Ingeniería, Universidad de Santiago de Chile
Roberto Rozas
Laboratorio de Química Computacional, Departamento de Ciencias del Ambiente, Facultad de Química y
Biología, Universidad de Santiago de Chile, Casilla 40, Correo 33, Santiago, Chile
Malaria is a disease caused by a parasite. There are an estimated 300-500 million cases of malaria
each year in the world resulting in over 1-2 million deaths. Although the discovery of artemisinin, a
natural endoperoxide sesquiterpene lactone and various of its analogues have shown high
antimalarial activity against the resistant Plasmodium falciparum and there has been efforts on
vaccine development, this has not yet made a significant contribution to controlling the disease and
still the search for antimalarial drugs having increased half-lives and minimum side effects is of
current interest.
In this work, 63 derivatives of 2-aziridyl, 3-aziridyl, and 2,3-bis(aziridyl)-1,4-naphthoquinonyl
sulfonate and acylate (structure (I)) having known antimalarial activity1 were studied by means of
multiple linear regression (MLR) in order to get both a quantitative structure-activity relationship
that can be used as a predictive tool useful for antimalarial drug design and obtention of structural
knowledge useful to make a contribution to the mechanism of action or to the intermolecular
interactions of studied compounds.
O
1
4
R3
R1
R2
O
(I)
Structures were first optimized by semiempirical methods (AM1 included in Hyperchem 7.5)2 and
then optimized by ab initio methods at the DFT B3LYP/6-31G* level of Gaussian 98W.3
Furthermore 165 descriptors were calculated for each structure using Codessa 2.6.4 The results of
correlation analysis using the Best Multi-Linear Regression method show that the antimalarial
activity of structure (I) derivatives is strongly dependent on both electrostatic character and
hydrogen bond acceptor properties, being the charge on oxygen of carbonyl group of position 4, the
most important descriptor.
Acknowledgements: DICYT – USACH Project Nº 060441CF and SDT – USACH Project CIA 2981.
1.
2.
3.
4.
Zahouily, M.; Lazar, M.; Elmakssoudi, A.; Rakik, K.; Elaychi, S.; Rayadh, A. J Mol Model (2006) 12: 398-405.
Hyperchem (TM) Professional 5.1, Hypercube, Inc., 1115 NW 4th Street, Gainesville, Florida 32601. USA.
Gaussian, Inc. Carnegie Office Park, Building 6, Suite 230 Carnegie, PA 15106 USA.
Comprehensive Descriptors for Structural and Statistical Analysis, Semichem, http://www.semichem.com.
55
Poster 25
Ab initio All-Electron Relativistic Calculations on the Series of
[Re(CN)6]n- Complexes (n = 1 to 5).
Luis Álvarez-Thon and Ramiro Arratia-Perez
Keywords: transition metal, spin orbit coupling, relativistic effects.
There exists an increasing interest in the chemistry and properties of transition metal-cyanide
complexes due to their possible use for an assortment of applications that include electronics,
magnetism and catalysis.1,2 Thus, the transition metal-cyanide complexes are viewed as useful
molecular precursors, which can be, incorporated into high–nuclearity clusters with adjustable
magnetic properties and could be of utility in the design of cyano-bridged materials with potentially
technological applications.1-5 It is expected that the incorporation of third-row transition metal
complexes may enhance the utility of such materials since these third-row transition metals possess
higher-energy valence d orbitals that may induce magnetic anisotropy due to the effects of
significant spin-orbit coupling.4,5
The purpose of this investigation is to determine accurate calculations on molecular properties of
[Re(CN)6]n- complexes (n=1 to 5), by the Relativistic Dirac-Hartree-Fock (DHF) method
implemented in the DIRAC6 code. This relativistic four-component formalism has no
approximations and includes the spin-orbit interaction implicitly and has proven to be the best
method for heavy atom studies.
Acknowledgements: We thank Fondecyt 1030148 ,UNAB DI-12-04 , Millenium Nucleus No. P02-004-F for their
support.
References
1. Ferlay, S.; Mallah, T.; Ouahes, R.; Veillet, P. ; Verdaguer, M. Nature 1995, 378, 701; Dunbar, K. R.; Heintz, R. A.
Prog. Inorg. Chem. 1997, 45, 283; (c) Yet, L. Angew. Chem. Int. Ed. Engl. 2001, 40, 875.
2. Khan, O.; Martinez, C. J. Science 1998, 279, 44; Berlinguette, C. P.; Smith, J. A. ; Galan-Mascaros, J. R.;
Dunbar, K. R. C. R. Chimie 2002, 5, 665.
3. Bennett, M. V.; Long, J. R. J. Am. Chem. Soc. 2003; 125, 2394.
4. Sokol, J. J.; Hee, A. G.; Long, J. R. J. Am. Chem. Soc. 2002, 124, 7656.
5. Beltran, L. M. C.; Long, J. R. Acc. Chem. Res. 2005, 38, 325.
6. DIRAC, a relativistic ab initio electronic structure program, Release DIRAC04.0 (2004)", written by H. J. Aa.
Jensen, T. Saue, and L. Visscher with contributions from V. Bakken, E. Eliav, T. Enevoldsen, T. Fleig, O.
Fossgaard, T. Helgaker, J. Laerdahl, C. V. Larsen, P. Norman, J. Olsen, M. Pernpointner, J. K. Pedersen, K.
Ruud, P. Salek, J. N. P. van Stralen, J. Thyssen, O. Visser, and T. Winther. (http://dirac.chem.sdu.dk) .
56
Poster 26
Theoretical-Experimental Correlation by Spectroscopy UV-Visible of
[RuH(CO)(dppz-R)(PPh3)2]+ Complexes (R= Cl, Me, H)
Mauricio Yañez1,2, Sergio A. Moya1, Gloria I. Cárdenas-Jirón2
1
2
Laboratory of Coordination Chemistry and Catalisis,
Laboratory of Theoretical Chemistry, Faculty of Chemistry and Biology, University of Santiago de Chile, Zip 40,
Mail 33, Santiago, CHILE
[RuH(CO)(dppz-R)(PPh3)2]+ complexes with R= Cl, Me and H were characterized by UV-Visible
spectroscopy (Figure), and a rationalization of the experimental bands registered in the spectrum
was performed in terms of electronic transitions between molecular orbitals
(⎯⎯) [RuH(CO)(dppz)(PPh3)2]+; (⎯⎯) [RuH(CO)(dppz-Cl)(PPh3)2]+; (⎯⎯) [RuH(CO)(dppz-CH3)(PPh3)2 ]+
Fully optimized molecular structures of [RuH(CO)(dppz-R)(PPh3)2]+ complexes using the Hartree
Fock semi-empirical PM3(tm) level of calculation in gas phase were obtained. Molecular orbitals
(MO) of these complexes were obtained by single point calculations with B3LYP/LACVP(d,p).
The lower energy band (≈ 350-390 nm) was associated to a HOMO→ LUMO transition (Figure
only shows the HOMO(A) to LUMO (B) transition for the [RuH(CO)(dppz-Cl)(PPh3)2]+ complex).
In contrast, the bands observed in the 220-280 nm range have been associated to HOMO1→LUMO+3 and HOMO-1→LUMO+2 transitions.
Acknowledgements. The authors thank the financial support provided by FONDECYT (Projects Nº 1050168 and
Nº 1060203) and FONDECYT Lineas Complementarias (Project Nº 8010006). My thanks to CONICYT by a
Doctoral Fellowship.
57
Poster 27
Electronic Structure of [ 4.4’-R(bpy)2 Ru Phpy] +
bpy=2,2’bypiridine , Phpy= Phenyl pyridine
Mauricio Barrera, Mauricio Arias, Max Quinteros and Barbara Loeb
Facultad de Química, Pontificia Universidad Católica de Chile, Casilla 306, Santiago Chile
During the last years the family of Ruthenium complexes [ Ru(R,bpy)2 L2 ]0,+2 (L2 is a bidentate ligand o two
monodentate ligands) has been subject to intensive studies due to their potential use as sensitized dye on
TiOr- based, solar cell devices[1]. The key role of the dye is to capture the visible light and transfer it to the
semiconductor band gap as a photocurrent. The L2 ligand also plays an important role; it is responsible of
tuning the optical properties of the dye with the visible part of the solar emission spectrum. Among of all
possible L2 ligands, we focused our research on the Phenyl pyridine derivates due to their well-known σdonor properties that rise the t2g metal orbitals.
Density Functional Theory methods, due to their good predictive results, could be employed as a guiding
tool for helping synthesis design. In accordance with this approach, we start a series of theoretical studies
over a family of Ruthenium compound containing cyclometalated ligands. We focus our calculations on
predicting the bathochromic displacement of the MLCT band, and the role of the position of the anchor on
redirecting the electronic density.
FIG 1
FIG 2
Geometrical optimization was done with a DZ basis set and VWN exchange functional. Energy levels where
calculated with ZORA-DZ basis set for Ruthenium and the LB94 exchange functional with corrected
asymptotic decay. Simulated absorption spectra was carried out with TDDFT-ALDA methodology.
Results. On figure 1 the Molecular Orbital Diagram show how the HOMO level move to higher energies due
to the presence of cyclometaleted ligand while the LUMO orbital remain unchanged. The net result is
displayed in Figure 2 where one of the MLCT band of [Ru(Bpy)3]+2 appearing at 500 nm moved to 560nm
on [Ru(Bpy)2Phpy]+
References
[1] N. Robertson, Angw. Chem. Int. Ed. 2338,45,(2006)
Acknowledgments. We would like to acknowledge Facultad de Quimica and Direccion de Investigacion de
Post grado of Pontificia Universidad Catolica
58
Poster 28
A theoretical model to study the Maillard reaction: Schiff base
formation.
Patricio Flores Morales1,2, Eduardo Silva1, Soledad Gutiérrez-Oliva2, and
Alejandro Toro-Labbé2.
1
2
Laboratorio de Química Biológica (QBUC), Pontificia Universidad Católica de Chile, Casilla 306, Santiago,
Chile.
Laboratorio de Química Teórica Computacional (QTC), Facultad de Química, Pontificia Universidad
Católica de Chile, Casilla 306, Santiago, Chile.
The Maillard reaction and Advanced Glycation End Products (AGEs) formation has been the subject
of intense literature scrutiny [1]. This reaction involves an ε-amino group of lysine aminoacid in a
protein, and a sugar like glucose or threose. The AGEs are cross-linked proteins which are the cause
of many diseases, including cataract formation. Attempts to theoretically describe the first step of
Maillard reaction (Schiff base formation) has been made at ab initio and Density Functional Theory
(DFT) calculations [2-3], although this is the first attempt of using conceptual DFT combined with
the chemical force profile [4-6] to rationalize the reaction (Figure 1).
REACTANT
TS
PRODUCT
Figure 1. Reaction between methylamine and 2-hydroxypropanal. Formation of a carbinolamine, previous to Schiff base.
The Schiff base formation reaction between methylamine and 2-hydroxypropanal has been studied
using DFT calculations at the B3LYP level with a 6-311G* basis set, the mechanism is explained in
terms of the behavior along the reaction coordinate of chemical potencial, hardness and electronic
local properties. The results show the quantification of works along the reaction path for the Schiff
base formation. In addition, the global and local properties have been monitored, through electronic
and structural changes to characterize the mechanism of this reaction.
[1]
[2]
[3]
[4]
A. W. Stitt, Ann. N.Y. Acad. Sci. 1043 (2005) 582-597.
N. E. Hall and B. J. Smith, J. Phys. Chem. A, 102 (1998) 4930-4938.
A. Salvà, J. Donoso, J. Frau and F. Muñoz, J. Phys. Chem. A, 107 (2003) 9409-9414.
P. Politzer, A. Toro-Labbé, S. Gutiérrez-Oliva, B. Herrera, P. Jaque, M. Concha and J. S. Murray, J. Chem. Sci.
117 (2005) 467-472.
[5] S. Gutiérrez-Oliva, B. Herrera, A. Toro-Labbé and H. Chermette, J. Phys. Chem. A, 109 (2005) 1748-1751.
[6] A. Toro-Labbé, S. Gutiérrez-Oliva, M. Concha, J. S. Murray and P. Politzer, J. Chem. Phys. 121 (2004) 4570.
Acknowledgments. Financial support from FONDECYT through projects N◦ 1060590 and 1050965, and project
CONICYT-Bicentenario N◦ 8 is gratefully acknowledged. P. Flores M. wants to thank to CONICYT for a doctoral
fellowship and Dr. Pablo Jaque for helpful discussion.
59
Poster 29
Optical Properties of Mo6I142- Cluster
Rodrigo Ramirez-Tagle, Ramiro Arratia-Pérez
República 275, Santiago, Chile. [email protected], [email protected]
The development of novel inorganic materials of technological interest certainly requires an
understanding of the electronic structure, spectroscopy, photophysical and structural properties of
metal clusters. In particular the Mo6X142- (X= Cl, Br) cluster ions exhibit interesting spectroscopic
and photophysical properties, and represent a new class of photoreceptors for light-induced chemical
reactions. Moreover, they are chemically stable under a variety of conditions, and they undergo
facile electron-transfer reactions in their ground and excited states.1
Based on these properties, a optical fiber based oxygen sensor for power plant applications have
been developed; where it is observed that the luminescence signal increases with decreasing oxygen
concentration.2
We report the geometry optimizations of the Mo6I142- cluster6 in vacuum, which were carried out
using the Amsterdam density functional code (ADF).3 We calculated the cluster excitation energies
using time-dependent perturbation density functional theory approach (TDDFT)4,5 including solvent
effects to rationalize their optical spectra. Our calculated values on the LMTC transitions and the
oscillator strengths of Mo6I142- suggest that this anion could be luminescent .
Acknowledgment. This work has been supported in part by Fondecyt No.1030148, UNAB-DI 12-04, and the
Millennium Nucleus of Applied Quantum Mechanics and Computational Chemistry, P02-004-F.
(1) A.W. Maverick, J.S. Najdzionek, D. Mackenzle, D.G. Nocera , H.B. Gray , J. Am. Chem. Soc., (1983) 105 , 7 ,
1878.
(2) R.N. Ghosh, G.L. Baker, C. Ruud, D.G. Nocera, App. Phys. Lett. (1999) 75 , 19 , 2885.
(3) Amsterdam Density Functional (ADF) code , release 2004 , Vrije Universiteit , Amsterdam , The Netherlands.
(4) M.E. Casida, C. Jamorski, K.C. Casida, D.R. Salahub, J. Chem. Phys. (1998) 108 , 4439.
(5) E van Lenthe , J.G. Snigders, E.J. Baerends, J. Chem. Phys. (1996) , 105 , 15 , 6505.
(6) K. Kirakci, S Cordier , C Perrin , Z. Anorg. Allg. Chem. , (2005),631,411.
60
Poster 30
Relativistic Electronic Structure of Anionic Icosahedral Cage Clusters
[M@Au12]— M = Nb, Ta, W, Pd and Au
L. Hernández-Acevedoa and R. Arratia-Perezb
a
b
Av. Los Libertadores, El Monte, Región Metropolitana, Chile. [email protected]
Departamento de Ciencias Químicas, Universidad Andres Bello, República 275, Santiago, Chile.
[email protected]
Gold clusters and metallic nanoparticles posses remarkable catalytic properties and potential
applications in nanoelectronics and nanosensors (see, in M. Haruta, Catal. Today 36, 153 (1997).
The chemistry of gold is dominated by strong relativistic effects and the aurophilic attraction.1 In
previous studies on neutral Pd@Au12 we have shown that Pd atom located in the center of the
icosahedral (Ih) Au12 cage increases the softness (S) of the cluster compared against the icosahedral
Au13 cluster. In fact, S = 4.0 eV-1 for Pd @Au12, while S = 3.4 eV-1 for Au13.2
Two years ago Wang et al. reported the observation and characterization of stable bimetallic 18valence-electron icosahedral gold clusters with an encapsulated central heteroatom of transition
metals, namely, [M@Au12]− Μ = V, Nb and Ta,3 where the electronic properties of these clusters
were probed by anion photoelectron spectroscopy.
Here we report the electronic structure and density of states (DOS) of these clusters obtained by the
Dirac Scattered Wave (DSW) four-component method. These results are compared against twocomponent relativistic calculations and against their observed photoelectron spectra.
Acknowledgements: We thank Fondecyt 1030148, UNAB DI-12-04, and the Millennium Nucleus of Applied
Quantum Mechanics and Computational Chemistry (P02-004-F) for their support.
References
1 P. Pykko, Angew. Chem. Int. Ed. 43, 4412 (2004).
2 R. Arratia-Pérez, L. Hernández-Acevedo Chem. Phys. Lett. 303, 641 (1999).
3 H-J. Zhai, J. Li, L-S. Wang, J. Chem. Phys. 121, 8369 (2004).
61
Poster 31
Structure-Antioxidant Activity Relationships of Flavonoids
Rodrigo Ramirez–Taglea, Wilson Cardona-Villadab, Héctor Carrasco-Altamiranob,
Claudio Gallardob, Alvaro Aballayc, Francisco Cañasb y Luis Espinoza-Catalánc.
a
b
c
República 275, Santiago, Chile. [email protected]
Los Fresnos 52, Viña del Mar, Chile.
Departamento de Química, Universidad Federico Santa María. Avenida España 1680, Valparaíso, Chile
Flavonoids belong to a group of naturally occurring compounds with a large number of biological
activities, the antioxidant activity arises from flavonoids ability to scavenge free radicals and thus
eliminate reactive oxygen species.1 The mechanism by which antioxidant can play their protective
role has been proposed,2 the free radical removes a hydrogen atom from the antioxidant (ArOH) that
itself becomes a radical: R* + ArOH → RH + ArO*
This mechanism is referred to an H-atom transfer. A higher stability of the radical ArO* correspond
to a better efficiency of the antioxidant ArOH, so that it is unlikely to react with the substrate. In this
mechanism the bond dissociations enthalpy (BDE) of the O-H bond is an important parameter in
evaluating the antioxidant action, because the weaker the OH bond the easier will be the reaction of
free radical inactivations.3
We report the predicting activity of flavonoids antioxidant and analysis of R-substituent effects on
the hydroxyl group. (Fig 1). Theoretical calculations were done by using density functional theory
(DFT) with a hybrid functional including a mixture of Hartree-Fock exchange with DFT exchange
correlation. All quantum chemistry calculations were performed with Gaussian 034 and B3LYP/631G* basis set.
The ∆E of dehydrogenation were determined by calculating the differences between radicals and
their parent flavonoids. Radicals were constructed by an abstraction of hydrogen atom from the
corresponding hydroxyl moiety.
All products are been synthesized in our laboratory in order to evaluate their antioxidant activity.
OMe
MeO
O
R
OMe
OH
O
R: H; NO2; NH2; NHCH3; NHCOCH3; OH
Figure 1. Structures of Flavonoids
(1) P-G
Pietta, J. Nat.Prod. , 2000, 63, 1035
J.S. Wright, E.R Johnson, G.A. DiLabio, J. Am.Chem.Soc., 2001 123, 1173
(3) M. Leopoldini, T. Marino, N. Russo, M. Toscano, J.Phys.Chem. A, 2004, 108, 4916.
(4) Frisch, M. J.; et al. Gaussian 03.
(2)
62
Poster 32
Study of the aromaticity development in the trimerization reaction of
mono-substitued acetylene analogs
Oscar Donoso-Tauda, Carlos A. Escobar and Juan C. Santos*
Departamento de Ciencias Químicas, Facultad de Ecología y Recursos Naturales, Universidad Andrés Bello.
Av. República 275, Santiago, Chile. [email protected]
We have studied theoretically the reaction mechanism and the aromaticity development in the
trimerization reaction of mono-substituted acetylenes (see Scheme 1). All the structures analyzed
were obtained in the framework of density functional theory using B3LYP/6-311G* level of theory.
The electronic study was done using the electron localization function, ELF,1 which determines the
domains of structural stability of the ELF topology along the intrinsic reaction path.
H
X
X
X
X
H
H
X
X
X=F, CN, CHO,OH
Scheme 1. Trimerization reaction of acetylene analogs
The activation barrier for the trimerization reaction is 43.0, 45.2, 47.1 and 58.0 kcal/mol forX= F,
CO, OH and CN, respectively. The low energy barrier in the F substituted acetylene can be
attributed to a lower steric effect and also to a stabilizing interaction produced by a in-plane
inductive effect, where the sigma bond is being formed. The main contributions from the other
sustituents are produced out-of-plane via resonance.
The analysis of the ELF separated into in-plane, ELFσ and out-of-plane, ELFπ2 contributions shows
that π aromaticity is developed at the final stage of the reaction and that the transition structures
have only low σ electron delocalization, this last being the most affected by the substituents
inductive effect.
Acknowledgements. Millennium Nucleus for Applied Quantum Mechanics and Computational Chemistry, Nº
P02-004-F (Mideplan-Conicyt) and Dirección General de Investigación, UNAB Grant DI-22-05/R. O. D. thanks to
UNAB for graduate fellowship.
References
1 A. D. Becke, K. E. Edgecombe, J Chem Phys., 92, 5397, 1990
2 Juan C. Santos, Juan Andres, Arie Aizman, and Patricio Fuentealba, J. Chem. theory and comp., 1, 83, 2005
63
Poster 33
Four component calculation of Nuclear magnetic shieldings for
Interhalogen molecules. Spin orbit and spin free relativistic effects
Sergio S. Gomez and RamiroArratia-Perez
Facultad de Ecologia y Recursos Naturales, Universidad Andrés Bello. [email protected]
There is an increasinginterest in understandingthe electronic origin of relativistic effects in nuclear
magnetic shielding tensor σ(N) of the NMR spectra. The Heavy Atom on Light Atom(HALA)
effect, which is the relativistic modification of σof the light atom due to the heavy atom in the
molecule, can be explained trough the Spin Orbit mechanism(SO)(1). On the other hand there is a
relativistic effect on the Heavy Atom due to the Heavy Atom(HAHA) itself, whose origin was
proposed recently in terms of the paramagnetic Mass Velocity External Field(MVEF) mechanism.
Previous calculations of this terms in molecules containing Hydrogen and one heavy atom shows
that indeed this mechanism account for more than 90% of the relativistic corrections of the
paramagnetic part of σ at the heavy atom, regardless the structure of the molecule(2,3). However, in
this presentation we show trough ab-initio four components calculations with FX(X=F,Cl,Br,I), how
the inclusion of Fluoride instead of Hydrogen in the molecule enhances the Spin Orbit contribution
to a value of the order of MVEF term. This results suggest that the interpretation of HAHA effect as
MVEF mechanism should be taken carefully.
Bibliography
(1) M. Kaupp, O.L. Malkina, V. G. Malkin and P. Pyykko, Chem. Eur. J. 4, 118(1998)
(2) L. Visscher, T. Enevoldsen, T. Saue, H. J. Aa Jensen, J. Oddershede, J.Comp. Chem. 20, 162(1999).
(3) Sergio S. Gomez, Rodolfo H. Romero and Gustavo A. Aucar, Chem. Phys. Lett 367, 265(2003).
Acknowledgements. Núcleo Milenio P02-004-F and Facultad de Recursos Naturales, UNAB.
64
Poster 34
Estructura electrónica y propiedades fluorescentes de
5-metoxi-6-hidroxi-7 H-dibenzo[de,h] quinolin-7-ona en solución
Victoria Ortega V, Víctor Vargas C. y Julio De La Fuente
Laboratorio de Luminiscencia y Estructura Molécular, Departamento de Química, Facultad de Ciencias,
Universidad de Chile. Casilla 653, Santiago, Chile. [email protected]
Las oxoisoaporfinas son especies moleculares pertenecientes a la familia de derivados alcaloides
oxoisoquinolinas. Del punto de vista de la estructura electrónica, estas especies se caracterizan por
la presencia de electrones no enlazantes en el átomo de oxígeno ceto, lo que generan estados
electrónicos excitados de naturaleza n,π* y π,π*, otorgando a estos sistemas interesantes propiedades
luminiscentes, las que con frecuencia pueden ser moduladas por la naturaleza polar del medio.
La especie 5-metoxi-6-hidroxi-7 H-dibenzo[de,h] quinolin-7-ona, (DBQ), mostrada en la Figura 1,
presenta un enlace de hidrógeno intramolecular entre dos átomos de oxígeno, cuyo equilibrio puede
originar la presencia de especies tautoméricas ceto y enol
OMe
H O
O
H
OMe
O
O
N
N
Figura 1. Estructura de 5-metoxi-6-hidroxi-7 H-dibenzo[de,h] quinolin-7-ona
En esta trabajo presentamos un estudio de la estructura electrónica de las diferentes especies
tautoméricas de DBQ, con el objeto de dilucidar el rol que desempeña los estados electrónicos de
naturaleza n,π* y π,π* y el enlace de hidrógeno de hidrógeno intramolecular, en las propiedades
fluorescentes de DBQ en función de la propiedad polar de solventes no acuosos y del pH del medio
en solución acuosa.
Del punto de vista experimental el estudio se lleva a cabo empleando técnicas espectroscópicas de
absorción y fluorescencia de estado estacionario, donde se determinan parámetros como longitud de
onda de los máximos de absorción, emisión y los rendimientos cuánticos de fluorescencia. Los
parámetros cinéticos, como las constantes de velocidad de desactivación radiativa y no radiativa, son
determinados a través del tiempo de vida de fluorescencia, medidos mediante la técnica de
corrimiento de fase y modulación en función de la frecuencia de modulación de la radiación
incidente.
Del punto de vista teórico, el estudio realizado es apoyado por cálculos semiempíricos y Ab-initio
de orbitales moleculares, con el objeto de analizar distribución de la nube electrónica de la
diferentes especies tautoméricas, tanto en el estado fundamental y primer estado excitado.
Agradecimientos.
Proyecto Interno, Facultad de Ciencias, Departamento de Química, Universidad de Chile (2005-2006).
65
Poster 35
The Intrinsic reactivity of Histamine with H2 and H3 Receptors using
conceptual DFT.
José Vicente Correa y Alejandro Toro-Labbé
QTC, Facultad de Química, Pontificia Universidad Católica de Chile, Casilla 306, Correo 22, Santiago, Chile.
Histamine, 1H-imidazole-4(5)ethanamine is a biogenic amine. In recent years it was proposed an
interaction mechanism with the H2 receptor consisting in three specific regions able for binding, thus
allowing the tautomeric interconversion of Histamine.
Figure 1: Conformational equilibria of Histamine.
In this work we will focus our attention in the characterization of the conformational dependence of
the intrinsic reactivity of Histamine using DFT-based index such as chemical potential (µ),
molecular hardness (η) and electrophilicity index(ω). Reaction force profile along torsional angles
confirms the specific geometry of the tautomer able to interact with the receptor. The results suggest
that Histamine binds to the receptor as through an electronic transfer process that occurs while
histamine is in the extended conformation.
66
Poster 36
New shape descriptor derived from the Gyration tensor
Verónica Jiménez and Joel B. Alderete
Organic Chemistry Department, Universidad de Concepción, Casilla 160-C, Concepción, Chile
In this work, we introduce a new shape descriptor F derived from the molecular gyration tensor, in order to account for the mass
distribution in the molecular plane of aromatic compounds.
The gyration tensor G for a system with N components is a symmetrical second-order tensor, whose elements are defined as:
⎡ S xx
⎢
G = ⎢ S yx
⎢ S zx
⎣
S xy
S yy
S zy
S xz ⎤
⎥
S yz ⎥
S zz ⎥⎦
and
S ij =
1⎛ N
⎞
⎜ ∑ ia j a ⎟
N ⎝ a =1
⎠
i , j = x, y , z
(1)
The diagonalization of G provides eigenvalues (Si) and eigenvectors (vi), corresponding to the principal moments of gyration and the
coordinates of the principal symmetry axes of the molecule, respectively. From a statistical point of view, the eigenvalues Si represent
the square of the standard deviation of the atomic coordinates of the molecule in the principal axes system.
⎡ S1
S = ⎢⎢ 0
⎢⎣ 0
0
S2
0
0⎤
0 ⎥⎥
S 3 ⎥⎦
such as
S1 ≤ S 2 ≤ S 3
and
⎡ v1 ⎤
V = ⎢⎢v 2 ⎥⎥
⎢⎣v3 ⎥⎦
T
(2)
The eigenvalues Si provide valuable information about the spatial distribution of nucleus in a molecule. In the case of systems with
spherical symmetry S1=S2=S3, whereas for cylindrical molecules S1=S2<S3. In the particular case of planar molecules, S1=0. Herein
we propose that the mass distribution in the molecular plane of aromatic systems, can be represented by a shape index F defined as
F=
S2
S3
where
F ≥1
(3)
If the planar mass distribution is symmetric, F will be equal to one. Otherwise, F will be larger than one, in accordance with the
preferred mass distribution along one of the principal axes located in the molecular plane. As shown in Figure 1, F is useful to
account for the molecular shape change arising from o-, m- and p-substitution in aromatic compounds. In addition, it has been
observed that the higher the molecular elongation degree, the larger the value of F.
Figure 1.
Calculated shape index F for o-, m- and p-xilene
In the present work we implemented a MATLAB routine to calculate F from the molecular standard 3D-cartesian coordinates.
Further, the F index has been employed as a shape descriptor to account for the chromatographic retention times of several aromatic
molecules. It has been found that F successfully describes shape change effects on the chromatographic behaviour of aromatic
compounds.
References.
1. D.N. Theodorou, U.W. Suter, Macromolecules 18, 1206 (1985)
2. S. Rayne, M.G. Ikonomou, J. Chromat. A, 1016, 235 (2003)
67
Poster 37
Theoretical Study of the Solvent Effect in Amino-Imino Tautomerism in
Water Solution
William Tiznado, Edwin Perez
Departamento de Química, Facultad de Ciencias, Universidad de Chile, Casilla 653, Las Palmeras 3425,
Santiago, Chile. [email protected]
The relative stabilities of tautomers of 2—aminothiazolidine-4-one and 4-aminothiazolidine-2-one
considering their mono and trihydrated complexes have been calculated by Vanelin Enchev et al1, at
MP2/6-31+G(d,p) level of theory. They found that in absence of water the process of proton
transfer should no occur. When they add water molecules to help the transference it decreases the
energy barrier making the process faster. To simulate the effect of the solvent the authors used the
polarizable continuum model (PCM). Taken these results as material to comparison we applied a
discreet model to simulate the solvent effect. To include the water molecules of solvent in our
model the ONIOM2 method was applied, this methodology gives us the possibility of combine
different levels of quantum chemical methods as well as molecular mechanics methods in the same
calculus. In this work we have combined ab-initio MP2/6-31+G(d,p) calculus to the substrate
including the solvent molecules which participate directly in the proton transference and UFF
molecular mechanics calculations to the solvent water molecules. We compare the effect of the
model applied in the energy barriers for the proton transference and compare these with the
experimental reported dates.
Acknowledgments. Work supported by Millennium Nucleus for Applied Quantum Mechanics and Computational Chemistry
(Mideplan-Conicyt, Chile), grant P02-004-F.
1
2
V. Enchev, N. Markova, S. Angelova, J. Phys. Chem. A, 109, 8904 (2005).
M. Svensson, S. Humbel, R. Froese, T. Matsubara, S. Sieber, K. Morokuma, 100, 19357 (1996).
68
Poster 38
Development of software for visualization and evaluation of protein
sequence alignments and structural models, and for the visualization of
data from various protein analyses tools
Mera-Adasme, Raúl1, Briones-Jerez, Rodolfo1, Olea-Azar, Claudio1, Mendizabal, Fernando2
1
2
Facultad de ciencias químicas y farmacéuticas, Universidad de Chile
Facultad de ciencias, Universidad de Chile
The sequence alignment is the key phase for protein homology modeling, and, although there are applications
to produce alignments, it is usually needed to correct the program's output manually. Here we present a tool
developed to easy this process by allowing to visualize the structural context of an alignment.
Considering that visualization is often the best way to appreciate the structural significance of the description
of some protein's characteristics, and relations among them, we also present applications developed for
analyses of data from external programs (Qcontacts[1], for analyses of protein interfaces, CAVER[2] and
HOLE[3], both for analyses of protein cavities) which allows to graphically display the results with the
PyMOL[4] molecular visualization program. The three applications support the analyses of data for several
snapshots of a trajectory, thus rendering an animation.
Applications:
The applications presented in this work are :
Sguallino: A tool for graphical evaluation of
protein sequence alignments for homology
modelling, allowing to observe the gaps and the
alignment quality in the context of the 3D
structure of the template (Figure 1)
CaverAnalyzer and HoleAnalyzer: Tools for
graphically displaying (using the PyMOL
visualization program) descriptions of protein
cavities obtained with the CAVER and HOLE
programs, respectively.
QconsAnalyzer: An applications for graphically
displaying descriptions of protein-protein
interfaces. It uses data from the Qcontacts
software and the PyMOL program.
Acknowledgments: The authors want to manifest
their gratitude to the PyMOL community, in
particular to Dr. Warren DeLano, for their help
with the PyMOL API, and also to Dr. Jerry Tsai,
who kindly provided us with his Qcontacts
application.
References:
5. Fisher, TB, Holmes, JB, Parsons, JR, Tung, L, Hu, JC, Tsai, J, (2003), J Struct Biol, 153, 103-112.
6. Petřek, M, Otyepka, M, Banáš,P, Košinová, P, Koča, J, Damborský, J, (2006), BMC Bioinformatics, 7, 316.
7. Smart, OS, Goodfellow, JM, Wallace, BA (1993), Biophys J, 65 2455-2460.
8. DeLano, WL, The PyMOL Molecular Graphics System, (2002) on World Wide Web http://www.pymol.org
69
Poster 39
Quantum Calculations on the Selectivity Filter of a Potassium Channel
Mario A. Duque-Noreña, Eduardo E. Chamorro
Av. República, 275, Santiago, Chile
Keywords: Potassium Channel, Quantum Calculations, Selectivity Filter
Quantum calculations have been performed in the selectivity filter of a potassium channel1. The
backbone has been taken as the four subunits which conforms the molecule, including ions K+ or
Na+ in different positions. This simulate the passage of the ion through the structure (see Figure).
The conformational and coordination changes which undergo the carbonyl groups during the travel
of ions have been discussed. In addition, the role of carbonyl groups in the observed selectivity are
analyzed. 4
Figure. Only two subunits are depicted for clarity. The steps of the movement of the ion are indicated, from the S00 to S09 position. M1 and M2
corresponds to the positions of Na+ or K+. The arrows shown the atoms that are moving together.
Acknowledgements. This work has been supported by Fondecyt (Chile), grant 1030173 and the Millennium Nucleus for
Applied Quantum Mechanics and Computational Chemistry (Mideplan-Conicyt, Chile), grant P02-004-F. We thank the
Universidad Andres Bello (UNAB) by support through the Project UNAB-DI 16-04.
References
1. Doyle, D. A., Morais, Cabral J., Pfuetzner, R. A., Kuo, A., Gulbis, J. M., Cohen, S. L., Chait, B. T., and MacKinnon, R. Science.
1998, 280, 69.
2. Noskov, S. Y., Berneche, S., and Roux, B. Nature. 2004, 431, 830.
3. Asthagiri, D., Pratt, L. R., and Paulaitis, M. E. Journal of Chemical Physics. 2006, 125,
4. Huetz, P., Boiteux, C., Compoint, M., Ramseyer, C., and Girardet, C. J.Chem.Phys. 2006, 124, 044703.
70
Poster 40
Una Aproximación Teórica para la Inhibición contra el Tipo Silvestre
y Mutantes Virales de la Transcriptasa Reversa del VIH-1 por una serie
de derivados de la Tiazolidenbencensulfonamida.
Francisco Soto-Morales1 y Juan Sebastián Gómez-Jeria2.
1
2
Programa de Doctorado en Fisicoquímica Molecular. Universidad Andrés Bello, Facultad de Ecología y
Recursos Naturales, Departamento de Ciencias Químicas, República 275, Santiago, Chile.
Facultad de Ciencias, Departamento de Química, Casilla 653, Santiago, Chile.
El sello de los retrovirus es la enzima transcriptasa reversa (TR) que es el más antiguo y uno de los
principales blancos de la terapia contra el VIH-1. Estos inhibidores pueden ser clasificados dentro de
dos grupos: los inhibidores análogos de nucleósidos (IN), los cuales actúan competitivamente en el
sitio catalítico de la enzima bloqueando la elongación o producción de ADN a partir del ARN viral y
los inhibidores no-análogos de nucleósidos (INN), que inhiben la TR uniéndose en un sitio
alostérico cercano al sitio activo de la polimerasa. Los primeros exhiben diferentes grados de
toxicidad a nivel celular. Los segundos son más específicos y menos tóxicos. Sin embargo, los INN
inducen frecuentemente mutaciones virales, siendo las más características las mutaciones en los
residuos de los amino ácidos Lys103 a asparagina (mutante K103N) y Tyr181 a cisteína (mutante
Y181C), respectivamente. Por lo tanto es importante encontrar nuevos compuestos que puedan ser
capaces de superar la resistencia viral y que posean una alta capacidad inhibidora contra la TR.
Entre las moléculas que presentan una buena inhibición de la TR están los TBS, que representan una
nueva serie de INN de segunda generación. Se ha llevado a cabo un estudio de las relaciones entre la
estructura electrónico-molecular y la inhibición de la TR. Se ha empleado el método KPG, el cual
garantiza la obtención de buenos resultados dada su base físico-matemática. Se seleccionaron una
serie de derivados de TBS activos contra el tipo “silvestre” (wild-type) de TR (WT-TR), contra el
mutante K103N TR y contra el mutante Y181C TR. La geometría molecular fue completamente
optimizada con el método AM1. Las correspondientes funciones de onda se obtuvieron con el
método ZINDO/1. A partir de las funciones de onda se obtuvieron todos los índices de reactividad
de los átomos de un esqueleto común a todas las moléculas. Finalmente se llevó a cabo un análisis
de regresión lineal múltiple con la constante de inhibición como variable dependiente y los
descriptores atómicos del esqueleto común como variables independientes. Se obtuvieron tres
ecuaciones estadísticamente significativas que reflejan la variación de la constante de inhibición en
función de la variación de algunos índices de reactividad del esqueleto común. Se propone un
mecanismo de inhibición y se comparan los resultados con la literatura existente.
71
Poster 41
Ab initio Calculations on Interstellar Molecules
N. Inostroza1*, P. Fuentealba2, J. R. Letelier3
1
2
3
Facultad de Ecología y Recursos Naturales, Doctorado en Fisicoquímica Molecular, Universidad Andrés Bello
Facultad de Ciencias, Dpto. de Física, Universidad de Chile
Facultad de Ciencias Físicas y Matemáticas, Dpto. de Química, Universidad de Chile
The interstellar medium (ISM) is of vital importance for the galactic evolution. Stars are formed in
this ISM and the heavy-element enriched matter is given back to this medium. This is essential for
both the formation of planets and for the development and evolution of life. In the ISM have been
detected around 120-1301 molecules which exist in extreme conditions not found in our planet.
From this point of view, quantum chemistry calculations contributes with significant theoretical
information about this type of interstellar molecules.
The recent astronomical detection2 of the CF+ ion (fluoromethylidynium ion) have caught our
attention. This ion is a typical intermediary in the chemistry of fluorocarbons and is frequently used
in semiconductor devices and for this reason this cation is considered technologically quite
interesting.
In the present work, the potential energy curve (as a function of the internuclear distance R) of the
ground electronic state X1Σ+ was calculated by the MRCI/AVTZ method., allowing the numerical
resolution of the centrifugally-distorted Schrödinger equation3. For each value of J, a set of rovibrational energies {Eν,J} was calculated. Considering this, some of the most important bands of the
spectrum and spectroscopic constants have been calculated for CF+.
1.
2.
3.
Helger S. P. Muller, Frankschoder, Jurgen Stutzki, Gisbert Winnewiser, Journal of Molecular Structure 742, 215-227, (2005)
D.A.Neufeld et al., Astrochemistry: Recent Successes and Current Challenges Proceedings IAU Symposium No. 231,
(2005).
C. A. Ultreras-Diaz, J. R. Letelier, Computers chemistry 19, 39, (1995).
Acknowledgements. The Millennium Nucleus for Applied Quantum Mechanics and Computational Chemistry P02-004-F
72
Part icipants
page
PARTICIPANTS
Alvaro Aballay
62
Departamento de Química, Universidad Federico Santa María. Valparaíso, Chile.
Rodrigo Acevedo
37
Departamento de Química Orgánica y Físico-Química, Facultad de Ciencias Químicas y Farmaceúticas, Universidad de
Chile, Santiago, Chile.
E. Alarcón
39
Departamento de Química Biológica, Facultad de Química, Pontificia Universidad Católica de Chile, Santiago, Chile.
Joel B. Alderete
27, 32, 67
Organic Chemistry Department, Universidad de Concepción, Concepción, Chile.
Leonor Alvarado
49
Departamento de Ciencias Químicas, Facultad de Ecología y Recursos Naturales, Universidad Andrés Bello, Santiago,
Chile.
José Alvarez
55
Departamento de Ingeniería Informática, Facultad de Ingeniería, Universidad de Santiago de Chile, Santiago, Chile.
Luis Álvarez-Thon
56
Chile.
Jans H. Alzate-Morales
48
Departamento de Química, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
Mauricio Arias
58
Facultad de Química, Pontificia Universidad Católica de Chile, Santiago, Chile.
Chile.
38, 39, 40,
50, 53, 56,
60, 61, 64
Mauricio Barrera
25, 58
Ramiro Arratia-Pérez
Patrick Batail
12
Laboratoire Chimie, Ingénierie Moléculaire et Matériaux (CIMMA), UMR 6200 CNRS-Université d’Angers, France.
Cristhian Berríos
18
Laboratory of Theoretical Chemistry, Faculty of Chemistry and Biology, University of Santiago de Chile, Santiago, Chile.
Werner J. Blau
14
Professor of Materials Physics, Department of Physics, Trinity College, Dublin, Ireland.
Daniel Borquez-Macherone
45
Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
S. Brauchi
28
Centro de Bioinformática y Simulación Molecular, Universidad de Talca, Talca, Chile.
Rodolfo Briones-Jerez
69
Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.
F. Burgos
38
Instituto de Química, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile.
Carlos Bustos
40
Instituto de Química, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile.
M. Campos-Vallette
52, 54
Francisco Cañas
62
Departamento de Ciencias Químicas, Facultad de Ecología y Recursos Naturales. Universidad Andrés Bello, Viña del mar,
Chile.
73
Part icipants
page
Carlos Cárdenas
48
Chile.
Gloria I. Cárdenas-Jirón
18, 57
Wilson Cardona-Villada
62
Chile.
Héctor Carrasco-Altamirano
62
Chile.
David Carrillo
33
Laboratorio de Química Inorgánica, Instituto de Química, Pontificia Universidad Católica de Valparaíso, Valparaiso, Chile.
Bruce K. Cassels
34
Laboratorio de Química Biodinámica, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
H. Cerecetto
35
Department of Organic Chemistry, Faculty of Sciences, University of the Republic, Montevideo, Uruguay.
Eduardo Chamorro
41, 70
Chile.
Ivonne Chávez
38
Departamento de Química Inorgánica, Facultad de Química, Pontificia Universidad Católica de Chile, Santiago, Chile.
Niels Egede Christensen
13
Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C, Denmark.
M. Leonor Contreras
Laboratorio de Química Computacional, Departamento de Ciencias del Ambiente, Facultad de Química y Biología,
Universidad de Santiago de Chile, Santiago, Chile.
Jorge David
47, 48,
51, 55
38, 50
Chile.
Julio De La Fuente
37, 65
Eduardo J. Delgado
32, 46
Theoretical and Computational Chemistry Group, Faculty of Chemical Sciences, Universidad de Concepción, Concepción,
Chile.
Gerardo A. Díaz
46
Chile.
Daniela Donoso
43
Oscar Donoso-Tauda
63
Chile.
Mario A. Duque-Noreña
70
Departamento de Ciencias Químicas, Facultad de Ecología y Recursos Naturales, Universidad Andrés Bello, Av. República,
275, Santiago, Chile
A. M. Edwards
39
Carlos A. Escobar
63
Chile.
74
Part icipants
page
Luis Espinoza-Catalán
62
Departamento de Química, Universidad Federico Santa María. Valparaíso, Chile.
Patricio Flores Morales
59
Laboratorio de Química Biológica (QBUC), Pontificia Universidad Católica de Chile, Santiago, Chile.
Mauricio Fuentealba
19, 33
Laboratorio de Cristalografía, Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile,
Santiago, Chile.
Patricio Fuentealba
72
Departamento de Física, Facultad de Ciencias, Universidad de Chile
Claudio Gallardo
62
Chile.
A. M. García
39
María Teresa Garland
19
Laboratorio de Cristalografía, Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile,
Santiago, Chile.
Jorge Garza
20
Departamento de Química División de Ciencias Básicas e Ingeniería Universidad Autónoma Metropolitana-Iztapalapa,
Mexico
A. Gerpe
35
Department of Organic Chemistry, Faculty of Sciences, University of the Republic, Montevideo, Uruguay.
Sergio S. Gómez
64
Chile.
Juan S. Gómez-Jeria
W. González
52, 53,
54, 71
28, 29,
35
28, 29,
15
Doris Guerra
20, 50
Fernando Danilo González-Nilo
Chile.
Soledad Gutiérrez-Oliva
59
Laboratorio de Química Teórica Computacional (QTC), Facultad de Química, Pontificia Universidad Católica de Chile,
Santiago, Chile.
Lucía Hernández-Acevedo
61
Av. Los Libertadores, El Monte, Región Metropolitana, Chile.
Carmen Herrera S.
24
Departamento de Ingeniería Química, Universidad Tecnológica Metropolitana, Santiago, Chile.
Natalia Inostroza
72
Programa de Doctorado en Fisicoquímica Molecular. Facultad de Ecología y Recursos Naturales, Universidad Andrés Bello,
República 275, Santiago, Chile.
Gonzalo A. Jaña
32, 46
Chile.
Paul Jara
42
Laboratorio de Síntesis Inorgánica y Electroquímica, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
Paula Jaramillo
22, 36
Chile.
75
Part icipants
page
Verónica Jiménez
27, 67
Organic Chemistry Department, Universidad de Concepción, Concepción, Chile.
Carolina Jullian
30, 37
Departamento de Química Orgánica y Fisicoquímica. CEPEDEQ., Universidad de Chile, Santiago, Chile.
Erika Lang
42
Centro de Equipamiento Mayor, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
Robert Laskowski
13
Institute of Materials Chemistry, Technical University of Vienna, Austria.
R. Latorre
28
J. Ricardo Letelier D.
24, 72
Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago,
Chile.
P. Leyton
52, 54
Barbara Loeb
58
D. Mac-Leod Carey
38, 39,
40
38, 39,
40
Carolina Manzur
33
Juan M. Manríquez
Laboratorio de Química Inorgánica, Instituto de Química, Pontificia Universidad Católica de Valparaíso, Valparaiso, Chile.
C. Mascayano
28
Fernando Mendizabal
69
Fernando Mendizábal
23, 43
Raúl Mera-Adasme
69
Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.
Juan Merchán
42
German Miño
47
Chile.
Sebastián Miranda-Rojas
30, 45
Department of Inorganic and Analytical Chemistry, Faculty of Chemical and Pharmaceutical Sciences, University of Chile,
Santiago, Chile.
Otilia Mó
21
Sergio A. Moya
57
Laboratory of Coordination Chemistry and Catalysis, University of Santiago de Chile, Santiago, Chile.
A. Muñoz
38, 40
Claudio Olea-Azar
Departamento de Química Inorgánica y Analítica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile,
Santiago, Chile.
Walter Orellana
30, 35,
45, 69
26
Departamento de Física, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
76
Part icipants
page
Teresita Orosteguis
30
Santiago, Chile.
G. Orta
28
Victoria Ortega V.
65
Laboratorio de Luminiscencia y Estructura Molecular, Departamento de Química, Facultad de Ciencias, Universidad de
Verónica Paredes-García
18
Faculty of Natural Sciences, Mathematics and Environment, Metropolitan Technological University, Santiago, Chile.
Edwin Pérez
68
Patricia Pérez
22, 41
Departamento de Física, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
Edwin G. Pérez Hernández
34
Laboratorio de Química Biodinámica, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
Hernán Pessoa
37
Max Quinteros
58
N. Raddatz
28
Rodrigo Ramirez-Tagle
60, 62
Chile.
Elizabeth Rincón B.
21
Santiago, Chile.
Jorge Rodríguez
35, 44
Department of Inorganic and Analytical Chemistry, Faculty of Chemical and Pharmaceutical Sciences, University of Chile,
Santiago, Chile.
Franklin Rosales-Salazar
18
Roberto Rozas
55
Laboratorio de Química Computacional, Departamento de Ciencias del Ambiente, Facultad de Química y Biología,
Universidad de Santiago de Chile, Santiago, Chile.
G. Saavedra
29
Jean Yves Saillard
11
UMR 6226 Sciences Chimiques de Rennes, Université de Rennes 1, 35042 Rennes Cedex, France.
Claudio Saitz
37
Constain H. Salamanca
36
Juan C. Santos
Chile.
Eduardo Silva
48, 49,
63
59
Laboratorio de Química Biológica (QBUC), Pontificia Universidad Católica de Chile, Santiago, Chile.
77
Part icipants
page
Jorge Soto-Delgado
51
Francisco Soto-Morales
71
Programa de Doctorado en Fisicoquímica Molecular. Facultad de Ecología y Recursos Naturales, Universidad Andrés
Bello, República 275, Santiago, Chile.
Orlando Tapia
10
Department of Physical and Analytical Chemistry, Uppsala University, Box 579. S-751 23 Uppsala, Sweden.
22, 47, 48,
68
Alejandro Toro-Labbé
21, 59, 66
William Tiznado
Santiago, Chile.
H. Urbina
28, 29
Rubicelia Vargas
20
Departamento de Química División de Ciencias Básicas e Ingeniería Universidad Autónoma Metropolitana-Iztapalapa,
Mexico
Víctor Vargas C.
65
Laboratorio de Luminiscencia y Estructura Molecular, Departamento de Química, Facultad de Ciencias, Universidad de
Sergio O. Vásquez A.
17
Departamento de Ciencia de los Materiales, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Santiago,
Chile.
Andrés Vega
33
Chile.
Diego Venegas-Yazigi
18
CIMAT, Faculty of Chemical and Pharmaceutical Sciences, University of Chile, Santiago, Chile.
José Vicente Correa
66
Santiago, Chile.
M. Vidal
29
Mauricio Yañez
57
Laboratory of Coordination Chemistry and Catalysis, University of Santiago de Chile, Santiago, Chile.
Manuel Yáñez
21
Nicolás Yutronic
42
Gerald Zapata-Torres
Santiago, Chile.
30, 34, 45,
42, 44
78
Index
Index
Preface
1
J.J. Thomson
2
Sponsors
3
Program
4
Plenary Lectures
9
Chemical Quantum Diabatic States Approach as Complementary to Adiabatic BO procedures: On the he
role of spin-orbit interaction in chemical dynamics and reaction mechanisms
10
Pentalene and Acepentalene Coordination to Transition Metals: a DFT analysis
11
The Many Faces of the Materials Chemistry and Physics of the Organic-Inorganic Interface
12
13
Molecular assembly and templating for nanotechnology
14
15
Oral Lectures
16
Inclusion of oligomers in PHTP nanochannels. Conformational and spectroscopic aspects
using ONIOM and time dependent methodologies.
17
Rationalization of Charge Transfer Mechanisms Involving Porphyrin Derivatives Metal Complexes
18
19
20
Effect of Ni(II), Cu(II) and Zn(II) Association on the keto-enol Tautomerism of Thymine
21
22
Theoretical Study on the Electronic Spectrum of Bi- and Tri-nuclear Pt(II)-Au(I), Pt(II)-Ag(I), Pt(II)-Pt(II) and
Pt(II)-Pd/II) Complexes
23
24
25
Fe adatoms along Bi nanolines on H/Si(001): Patterning atomic magnetic chains
26
27
Simulación Molecular de la Interacción entre PIP2 y el canal TRPV1. (Molecular simulation of the PIP2TRPV1 channel interaction.)
28
Análisis Estructural del Poro del Canal de K+ HSLO a Través de Simulaciones de Dinámica Molecular.
29
79
Index
NMR and Molecular Modeling studies of cyclodextrin-catechin complexes
Posters
30
31
A First Approximation for the Elucidation of the Inhibition of Acetohydroxyacid synthase (AHAS) by
Chlorimuron Ethyl
32
A Density Functional Theory Investigation of a Ferrocenyl Ketoamine and Their Derivatives
33
Design of Possibles Nicotinic Acetylcholine Receptor Ligands
34
ESR and theoretical of 5-nitroindazole derivatives as potential antiparasitic drugs.
35
Experimental and theoretical study of N-alkylation of nitroimidazoic ring with alkyl halides
36
Studies of Chiral Recognition Properties by NMR of Novel Bridged Thiourea Chiral Calix[4]arenes
37
[Cp*-Ru-Indacene-Ru-Cp*]+Electronic Structure of a Mixed Valence Organometallic System
38
Effect of Peripheral or Non Peripheral Substitution Upon The Spectroscopic Properties of Zinc
Phthalocyanine.
39
π Donor / Acceptor Effect on Lindqvist type Polyoxomolybdates Functionalizated with Multiple-Bonding
Nitrogeneous Ligands
40
Electrophilicity and spin polarization within the framework of spin-polarized density functional theory
41
2D-ROESY NMR Studies and Molecular Modeling of Supramolecular Complexes of αCDDIALKYLAMINES
42
Theoretical Study in [C2H4-Tl]n+ and [C2H2-Tl]n+ (n = 2, 3) Complexes
43
Molecular Modeling of 5-HT2 receptors
44
Molecular modeling study on the interaction of Fe65 PTB2 Domain and AICD complex
45
Prediction of Octanol-Water Partition Coefficients of Chlorinated Biphenyls by Molecular Descriptors.
46
Nucleophilic Activation Of Charged Systems: Carbon Nanotube v/s Dielectric Models
47
Theoretical Study on CDK2 Inhibitors Using a Global Softness Obtained from the Density of States
48
Study of aromaticity of planar carbon clusters through the topological analysis of electron localization
function
49
Calculated Relativistic Nuclear Magnetic Shieldings on monohalides of noble metals
50
Endo/Exo Selectivity in Intermolecular Diels-Alder Reactions
51
Humic Acids As Molecular Assemblers in Sers Detection of Polycyclic Aromatic Hydrocarbons
52
On The “Metallicity” of Some Metallic Nanotubes
53
Carbon Nanotube as Molecular Assemblies: Surface-Enhanced Resonance Raman Spectroscopy
(SERRS) and Theoretical Studies
54
80
Index
Multiple Linear Regression Study of the Antimalarial Activity of Aziridinyl 1,4-Naphthoquinonyl Sulfonate
and Acylate Derivatives
55
Ab initio All-Electron Relativistic Calculations on the Series of [Re(CN)6]n- Complexes (n = 1 to 5).
56
Theoretical-Experimental Correlation by Spectroscopy UV-Visible of [RuH(CO)(dppz-R)(PPh3)2]+
Complexes (R= Cl, Me, H)
57
Electronic Structure of [ 4.4’-R(bpy)2 Ru Phpy] +bpy=2,2’bypiridine , Phpy= Phenyl pyridine
58
A theoretical model to study the Maillard reaction: Schiff base formation.
59
Optical Properties of Mo6I142- Cluster
60
—
Relativistic Electronic Structure of Anionic Icosahedral Cage Clusters [M@Au12] M = V, Nb and Ta
61
Structure-Antioxidant Activity Relationships of Flavonoids
62
Study of the aromaticity development in the trimerization reaction of mono-substitued acetylene analogs
63
Four component calculation of Nuclear magnetic shieldings for Interhalogen molecules. Spin orbit and spin
free relativistic effects
64
Estructura electrónica y propiedades fluorescentes de
5-metoxi-6-hidroxi-7 H-dibenzo[de,h] quinolin-7-ona en solución
65
The Intrinsic reactivity of Histamine with H2 and H3 Receptors using conceptual DFT.
66
New shape descriptor derived from the Gyration tensor
67
Theoretical Study of the Solvent Effect in Amino-Imino Tautomerism in Water Solution
68
Development of software for visualization and evaluation of protein sequence alignments and structural
models, and for the visualization of data from various protein analyses tools
69
Quantum Calculations on the Selectivity Filter of a Potassium Channel
70
Una Aproximación Teórica para la Inhibición contra el Tipo Silvestre y Mutantes Virales de la Transcriptasa
Reversa del VIH-1 por una serie de derivados de la Tiazolidenbencensulfonamida.
71
Ab initio Calculations on Interstellar Molecules
72
Participants
73
Index
79
Schedule
82
81
15:00 – 15:45
15:45 – 15:55
Setting up
Posters
Plenary Lecture 1
O. Tapia
Discussion
13:00 – 15:00
15:00 – 15:30
15:30 – 16:15
16:15 – 16:25
Dinner
20:00 – 22:00
17:30 – 19:30
17:05 – 17:25
16:45 – 17:05
16:25 – 16:45
15:55 – 16:15
11:40 – 12:00
11:20 – 11:40
5thWorkshop of Computational Chemistry and Molecular Spectroscopy
20:00 – 22:00
17:30 – 19:30
17:05 – 17:25
16:45 – 17:05
Oral 1
O. Vazquez
Oral 2
G. Cardenas
Poster
Presentation
13:00 – 15:00
Lunch
11:30 – 12:30
16:25 – 16:45
10:40 – 11:00
Welcome and Opening
Ceremony
Rolando Kelly J.
Academic Vice rector
UNAB
11:00 – 11:20
10:20 – 10:40
Dinner
Oral 8
R. Letelier
Oral 9
M. Barrera
Poster
Presentation
Oral 7
F. Mendizabal
Discussion
Plenary Lecture 3
P. Batail
Lunch
Oral 5
E. Rincon
Oral 6
P. Jaramillo
Oral 3
M. Fuentealba
Oral 4
D. Guerra
9:45 – 9:55
10:00 – 10:20
Discussion
9:00 – 9:45
Registration
República 252
Departure from
Breakfast
Plenary Lecture 2
J.-Y. Saillard
7:00 – 8:30
WEDNESDAY, 18
10:30 – 11:30
8:45
Bus to Punta de Tralca
TUESDAY, 17
Breakfast
Dinner
Social
22:30 –
Free Time
Lunch
Discussion
Plenary Lecture 5
W. Blau
Oral 10
W. Orellana
Oral 11
V. Jiménez
Discussion
Plenary Lecture 4
N. Christensen
20:00 – 22:00
15:00 – 20:00
AFTERNOON
13:00 – 15:00
12:05 – 12:15
11:20 – 12:05
11:00 – 11:20
10:40 – 11:00
10:20 – 10:40
10:00 – 10:20
9:45 – 9:55
9:00 – 9:45
7:00 – 8:30
MORNING
THURSDAY, 19
15:00
13:00 – 14:30
12:00 – 13:00
11:20 – 11:40
11:00 – 11:20
10:40 – 11:00
10:20 – 10:40
10:00 – 10:20
9:45 – 9:55
9:00 – 9:45
7:00 – 8:30
Bus
RETURN TO
SANTIAGO
Lunch
Poster
withdrawal
Round table
Oral 12
C. Mascayano
Oral 13
W. González
Oral 14
C. Jullian
Discussion
Plenary Lecture 6
D. Gonzalez
Breakfast
FRIDAY, 20
82
S c he d ul e

5th Workshop of Computational Chemistry and Molecular

Transcripción

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