2016 |
Munoz-Castro, A; Gomez, T; Carey, D M; Miranda-Rojas, S; Mendizabal, F; Zagal, J H; Arratia-Perez, R Surface on Surface. Survey of the Monolayer Gold-Graphene Interaction from Au-12 and Pah Via Relativistic Dft Calculations Artículo de revista Journal of Physical Chemistry C, 120 (13), pp. 7358-7364, 2016, ISSN: 1932-7447. Resumen | Enlaces | BibTeX | Etiquetas: ab-initio, approximation, chemistry clusters, density-functional generalized gradient hydrogen-bonds, interaction, monolayers, noncovalent phthalocyanines, pseudopotentials, self-assembled theory @article{RN303, title = {Surface on Surface. Survey of the Monolayer Gold-Graphene Interaction from Au-12 and Pah Via Relativistic Dft Calculations}, author = { A. Munoz-Castro and T. Gomez and D.M. Carey and S. Miranda-Rojas and F. Mendizabal and J.H. Zagal and R. Arratia-Perez}, url = {/brokenurl#<Go to ISI>://WOS:000373862700049}, doi = {10.1021/acs.jpcc.5b12580}, issn = {1932-7447}, year = {2016}, date = {2016-01-01}, journal = {Journal of Physical Chemistry C}, volume = {120}, number = {13}, pages = {7358-7364}, abstract = {Gold-graphene interaction at the interface is evaluated through different polyaromatic hydrocarbons (PAH), accounted by C6H6, C24H12, C54H16, and C96H18, focusing into different energetic terms related to the overall interaction. Our results characterize the neutral gold-PAH interaction nature with 45% of dispersion character, 35% of electrostatic, and 20% of covalent character, suggesting that moderate van der Waals character is mostly involved in the interaction, which increases according to the size of the respective PAH. The resulting surface charge distribution in the graphene model is a relevant parameter to take into account, since the ability of the surface charge to be reorganized over the polycyclic structure in both contact and surrounding regions is important in order to evaluate interactions and different interacting conformations. Our results suggest that for a Au-12 contact surface of radius 4.13 angstrom, the covalent, electrostatic and dispersion character of the interaction are effectively accounted in a graphene surface of about 6.18 angstrom, as given by circumcoronene, depicting a critical size where the overall interaction character can be accounted.}, keywords = {ab-initio, approximation, chemistry clusters, density-functional generalized gradient hydrogen-bonds, interaction, monolayers, noncovalent phthalocyanines, pseudopotentials, self-assembled theory}, pubstate = {published}, tppubtype = {article} } Gold-graphene interaction at the interface is evaluated through different polyaromatic hydrocarbons (PAH), accounted by C6H6, C24H12, C54H16, and C96H18, focusing into different energetic terms related to the overall interaction. Our results characterize the neutral gold-PAH interaction nature with 45% of dispersion character, 35% of electrostatic, and 20% of covalent character, suggesting that moderate van der Waals character is mostly involved in the interaction, which increases according to the size of the respective PAH. The resulting surface charge distribution in the graphene model is a relevant parameter to take into account, since the ability of the surface charge to be reorganized over the polycyclic structure in both contact and surrounding regions is important in order to evaluate interactions and different interacting conformations. Our results suggest that for a Au-12 contact surface of radius 4.13 angstrom, the covalent, electrostatic and dispersion character of the interaction are effectively accounted in a graphene surface of about 6.18 angstrom, as given by circumcoronene, depicting a critical size where the overall interaction character can be accounted. |
2014 |
Martinez-Cifuentes, M; Weiss-Lopez, B; Santos, L S; Araya-Maturana, R Intramolecular Hydrogen Bond in Biologically Active O-Carbonyl Hydroquinones Artículo de revista Molecules, 19 (7), pp. 9354-9368, 2014, ISSN: 1420-3049. Resumen | Enlaces | BibTeX | Etiquetas: ab-initio, bond bond, chemistry, derivatives, dft, diels-alder electrostatic hydrogen hydroquinone, inhibitors, molecular molecules, natural orbital, potential, quinones, radicals reaction, resonance, respiration, tumor-cell @article{RN215, title = {Intramolecular Hydrogen Bond in Biologically Active O-Carbonyl Hydroquinones}, author = { M. Martinez-Cifuentes and B. Weiss-Lopez and L.S. Santos and R. Araya-Maturana}, url = {/brokenurl#<Go to ISI>://WOS:000340036200041}, doi = {10.3390/molecules19079354}, issn = {1420-3049}, year = {2014}, date = {2014-01-01}, journal = {Molecules}, volume = {19}, number = {7}, pages = {9354-9368}, abstract = {Intramolecular hydrogen bonds (IHBs) play a central role in the molecular structure, chemical reactivity and interactions of biologically active molecules. Here, we study the IHBs of seven related o-carbonyl hydroquinones and one structurally-related aromatic lactone, some of which have shown anticancer and antioxidant activity. Experimental NMR data were correlated with theoretical calculations at the DFT and ab initio levels. Natural bond orbital (NBO) and molecular electrostatic potential (MEP) calculations were used to study the electronic characteristics of these IHB. As expected, our results show that NBO calculations are better than MEP to describe the strength of the IHBs. NBO energies (Delta E-ij((2))) show that the main contributions to energy stabilization correspond to LP ->sigma* interactions for IHBs, (O1O2)-O-center dot center dot center dot-H-2 and the delocalization LP ->pi* for O-2-C-2 = C-alpha(beta). For the (O1O2)-O-center dot center dot center dot-H-2 interaction, the values of Delta E-ij((2)) can be attributed to the difference in the overlap ability between orbitals i and j (F-ij), instead of the energy difference between them. The large energy for the LP O-2 ->pi* C-2 = C-alpha(beta) interaction in the compounds 9-Hydroxy-5-oxo-4,8, 8-trimethyl-1, 9(8H)-anthracenecarbolactone (VIII) and 9,10-dihydroxy-4,4-dimethylanthracen-1(4H)-one (VII) (55.49 and 60.70 kcal/mol, respectively) when compared with the remaining molecules (all less than 50 kcal/mol), suggests that the IHBs in VIII and VII are strongly resonance assisted.}, keywords = {ab-initio, bond bond, chemistry, derivatives, dft, diels-alder electrostatic hydrogen hydroquinone, inhibitors, molecular molecules, natural orbital, potential, quinones, radicals reaction, resonance, respiration, tumor-cell}, pubstate = {published}, tppubtype = {article} } Intramolecular hydrogen bonds (IHBs) play a central role in the molecular structure, chemical reactivity and interactions of biologically active molecules. Here, we study the IHBs of seven related o-carbonyl hydroquinones and one structurally-related aromatic lactone, some of which have shown anticancer and antioxidant activity. Experimental NMR data were correlated with theoretical calculations at the DFT and ab initio levels. Natural bond orbital (NBO) and molecular electrostatic potential (MEP) calculations were used to study the electronic characteristics of these IHB. As expected, our results show that NBO calculations are better than MEP to describe the strength of the IHBs. NBO energies (Delta E-ij((2))) show that the main contributions to energy stabilization correspond to LP ->sigma* interactions for IHBs, (O1O2)-O-center dot center dot center dot-H-2 and the delocalization LP ->pi* for O-2-C-2 = C-alpha(beta). For the (O1O2)-O-center dot center dot center dot-H-2 interaction, the values of Delta E-ij((2)) can be attributed to the difference in the overlap ability between orbitals i and j (F-ij), instead of the energy difference between them. The large energy for the LP O-2 ->pi* C-2 = C-alpha(beta) interaction in the compounds 9-Hydroxy-5-oxo-4,8, 8-trimethyl-1, 9(8H)-anthracenecarbolactone (VIII) and 9,10-dihydroxy-4,4-dimethylanthracen-1(4H)-one (VII) (55.49 and 60.70 kcal/mol, respectively) when compared with the remaining molecules (all less than 50 kcal/mol), suggests that the IHBs in VIII and VII are strongly resonance assisted. |
2013 |
Contreras, R; Aizman, A; Tapia, R A; Cerda-Monje, A Lewis Molecular Acidity of Ionic Liquids from Empirical Energy-Density Models Artículo de revista Journal of Physical Chemistry B, 117 (6), pp. 1911-1920, 2013, ISSN: 1520-6106. Resumen | Enlaces | BibTeX | Etiquetas: ab-initio, dielectric-constant, diels-alder elimination, kemp polarity, reaction, scale solvents, static @article{RN165, title = {Lewis Molecular Acidity of Ionic Liquids from Empirical Energy-Density Models}, author = { R. Contreras and A. Aizman and R.A. Tapia and A. Cerda-Monje}, url = {/brokenurl#<Go to ISI>://WOS:000315181600051}, doi = {10.1021/jp3114946}, issn = {1520-6106}, year = {2013}, date = {2013-01-01}, journal = {Journal of Physical Chemistry B}, volume = {117}, number = {6}, pages = {1911-1920}, abstract = {Two complementary models of Lewis molecular acidity are introduced and tested in a wide series of 45 room temperature ionic liquids (RTIL). They are defined in the context of the conceptual density functional theory. The first one, which we tentatively call the excess electronic chemical potential, assesses the electron accepting power of the RTIL by relating the H-bond donor acidity with the charge transfer associated to the acidic H-atom migration at the cation of the RTIL considered as a HB-donor species. This global index accounts for the molecular acidity of the cation moiety of the ionic liquid that takes into account the perturbation of the anionic partner. The second index is defined in terms of the local charge capacity modeled through the maximum electronic charge that the cation, in its valence state, may accept from an unspecified environment. Each model is compared with the experimental HB-donor acidity parameter of the Kamlet Taft model. The best comparison is obtained for a combination of both the excess electronic chemical potential and the local charge capacity. As expected, the correlations with the Kamlet Taft alpha parameter do not lead to a universal model of HB-donor acidity. Reduced correlations for limited series of structurally related RTIL are obtained instead. Finally, we illustrate the reliability and usefulness of the proposed model of RTIL molecular acidity to explain the cation-dependent solvent effects on the reactivity trends for cycloaddition, Kemp elimination, and Menschutkin reactions, for which experimental rate coefficients are available from literature.}, keywords = {ab-initio, dielectric-constant, diels-alder elimination, kemp polarity, reaction, scale solvents, static}, pubstate = {published}, tppubtype = {article} } Two complementary models of Lewis molecular acidity are introduced and tested in a wide series of 45 room temperature ionic liquids (RTIL). They are defined in the context of the conceptual density functional theory. The first one, which we tentatively call the excess electronic chemical potential, assesses the electron accepting power of the RTIL by relating the H-bond donor acidity with the charge transfer associated to the acidic H-atom migration at the cation of the RTIL considered as a HB-donor species. This global index accounts for the molecular acidity of the cation moiety of the ionic liquid that takes into account the perturbation of the anionic partner. The second index is defined in terms of the local charge capacity modeled through the maximum electronic charge that the cation, in its valence state, may accept from an unspecified environment. Each model is compared with the experimental HB-donor acidity parameter of the Kamlet Taft model. The best comparison is obtained for a combination of both the excess electronic chemical potential and the local charge capacity. As expected, the correlations with the Kamlet Taft alpha parameter do not lead to a universal model of HB-donor acidity. Reduced correlations for limited series of structurally related RTIL are obtained instead. Finally, we illustrate the reliability and usefulness of the proposed model of RTIL molecular acidity to explain the cation-dependent solvent effects on the reactivity trends for cycloaddition, Kemp elimination, and Menschutkin reactions, for which experimental rate coefficients are available from literature. |
2012 |
Bernales, V S; Marenich, A V; Contreras, R; Cramer, C J; Truhlar, D G Quantum Mechanical Continuum Solvation Models for Ionic Liquids Artículo de revista Journal of Physical Chemistry B, 116 (30), pp. 9122-9129, 2012, ISSN: 1520-6106. Resumen | Enlaces | BibTeX | Etiquetas: ab-initio, approach, carbon-dioxide, density dielectric-constant, free-energies, functionals, gas-phase green kinetics, molecular-dynamics simulations, solvents, static thermochemical universal @article{RN105, title = {Quantum Mechanical Continuum Solvation Models for Ionic Liquids}, author = { V.S. Bernales and A.V. Marenich and R. Contreras and C.J. Cramer and D.G. Truhlar}, url = {/brokenurl#<Go to ISI>://WOS:000306989800043}, doi = {10.1021/jp304365v}, issn = {1520-6106}, year = {2012}, date = {2012-01-01}, journal = {Journal of Physical Chemistry B}, volume = {116}, number = {30}, pages = {9122-9129}, abstract = {The quantum mechanical SMD continuum universal solvation model can be applied to predict the free energy of solvation of any solute in any solvent following specification of various macroscopic solvent parameters. For three ionic liquids where these descriptors are readily available, the SMD solvation model exhibits a mean unsigned error of 0.48 kcal/mol for 93 solvation free energies of neutral solutes and a mean unsigned error of 1.10 kcal/mol for 148 water-to-IL transfer free energies. Because the necessary solvent parameters are not always available for a given ionic liquid, we determine average values for a set of ionic liquids over which measurements have been made in order to define a generic ionic liquid solvation model, SMD-GIL. Considering 11 different ionic liquids, the SMD-GIL solvation model exhibits a mean unsigned error of 0.43 kcal/mol for 344 solvation free energies of neutral solutes and a mean unsigned error of 0.61 kcal/mol for 431 water-to-IL transfer free energies. As these errors are similar in magnitude to those typically observed when applying continuum solvation models to ordinary liquids, we conclude that the SMD universal solvation model may be applied to ionic liquids as well as ordinary liquids.}, keywords = {ab-initio, approach, carbon-dioxide, density dielectric-constant, free-energies, functionals, gas-phase green kinetics, molecular-dynamics simulations, solvents, static thermochemical universal}, pubstate = {published}, tppubtype = {article} } The quantum mechanical SMD continuum universal solvation model can be applied to predict the free energy of solvation of any solute in any solvent following specification of various macroscopic solvent parameters. For three ionic liquids where these descriptors are readily available, the SMD solvation model exhibits a mean unsigned error of 0.48 kcal/mol for 93 solvation free energies of neutral solutes and a mean unsigned error of 1.10 kcal/mol for 148 water-to-IL transfer free energies. Because the necessary solvent parameters are not always available for a given ionic liquid, we determine average values for a set of ionic liquids over which measurements have been made in order to define a generic ionic liquid solvation model, SMD-GIL. Considering 11 different ionic liquids, the SMD-GIL solvation model exhibits a mean unsigned error of 0.43 kcal/mol for 344 solvation free energies of neutral solutes and a mean unsigned error of 0.61 kcal/mol for 431 water-to-IL transfer free energies. As these errors are similar in magnitude to those typically observed when applying continuum solvation models to ordinary liquids, we conclude that the SMD universal solvation model may be applied to ionic liquids as well as ordinary liquids. |
Cerda-Monje, A; Aizman, A; Tapia, R A; Chiappe, C; Contreras, R Solvent Effects in Ionic Liquids: Empirical Linear Energy-Density Relationships Artículo de revista Physical Chemistry Chemical Physics, 14 (28), pp. 10041-10049, 2012, ISSN: 1463-9076. Resumen | Enlaces | BibTeX | Etiquetas: ab-initio, catalysis, dielectric-constant, diels-alder electrophilicity field-theory, functional index, models molecular-dynamics, reaction, solvation, static theory @article{RN106, title = {Solvent Effects in Ionic Liquids: Empirical Linear Energy-Density Relationships}, author = { A. Cerda-Monje and A. Aizman and R.A. Tapia and C. Chiappe and R. Contreras}, url = {/brokenurl#<Go to ISI>://WOS:000305890300028}, doi = {10.1039/c2cp40619e}, issn = {1463-9076}, year = {2012}, date = {2012-01-01}, journal = {Physical Chemistry Chemical Physics}, volume = {14}, number = {28}, pages = {10041-10049}, abstract = {Multiparameter linear energy-density relationships to model solvent effects in room temperature ionic liquids (RTILs) are introduced and tested. The model incorporates two solvent dependent and two specific solute-solvent parameters represented by a set of electronic indexes derived from the conceptual density functional theory. The specific solute-solvent interactions are described in terms of the electronic chemical potential for proton migration between the anion or cation and the transition state structure of a specific reaction. These indexes provide a quantitative estimation of the hydrogen bond (HB) acceptor basicity and the hydrogen bond donor acidity of the ionic solvent, respectively. A sound quantitative scale of HB strength is thereby obtained. The solvent dependent contributions are described by the global electrophilicity of the cation and nucleophilicity of the anion forming the ionic liquid. The model is illustrated for the kinetics of cycloaddition of cyclopentadiene towards acrolein. In general, cation HB acidity outweighs the remaining parameters for this reaction.}, keywords = {ab-initio, catalysis, dielectric-constant, diels-alder electrophilicity field-theory, functional index, models molecular-dynamics, reaction, solvation, static theory}, pubstate = {published}, tppubtype = {article} } Multiparameter linear energy-density relationships to model solvent effects in room temperature ionic liquids (RTILs) are introduced and tested. The model incorporates two solvent dependent and two specific solute-solvent parameters represented by a set of electronic indexes derived from the conceptual density functional theory. The specific solute-solvent interactions are described in terms of the electronic chemical potential for proton migration between the anion or cation and the transition state structure of a specific reaction. These indexes provide a quantitative estimation of the hydrogen bond (HB) acceptor basicity and the hydrogen bond donor acidity of the ionic solvent, respectively. A sound quantitative scale of HB strength is thereby obtained. The solvent dependent contributions are described by the global electrophilicity of the cation and nucleophilicity of the anion forming the ionic liquid. The model is illustrated for the kinetics of cycloaddition of cyclopentadiene towards acrolein. In general, cation HB acidity outweighs the remaining parameters for this reaction. |
2016 |
Surface on Surface. Survey of the Monolayer Gold-Graphene Interaction from Au-12 and Pah Via Relativistic Dft Calculations Artículo de revista Journal of Physical Chemistry C, 120 (13), pp. 7358-7364, 2016, ISSN: 1932-7447. |
2014 |
Intramolecular Hydrogen Bond in Biologically Active O-Carbonyl Hydroquinones Artículo de revista Molecules, 19 (7), pp. 9354-9368, 2014, ISSN: 1420-3049. |
2013 |
Lewis Molecular Acidity of Ionic Liquids from Empirical Energy-Density Models Artículo de revista Journal of Physical Chemistry B, 117 (6), pp. 1911-1920, 2013, ISSN: 1520-6106. |
2012 |
Quantum Mechanical Continuum Solvation Models for Ionic Liquids Artículo de revista Journal of Physical Chemistry B, 116 (30), pp. 9122-9129, 2012, ISSN: 1520-6106. |
Solvent Effects in Ionic Liquids: Empirical Linear Energy-Density Relationships Artículo de revista Physical Chemistry Chemical Physics, 14 (28), pp. 10041-10049, 2012, ISSN: 1463-9076. |