International Journal of Quantum Chemistry

Cover image for Vol. 112 Issue 21

Special Issue: Mexican Theoretical Physical Chemistry Meetings

5 November 2012

Volume 112, Issue 21

Pages i–iv, 3439–3557

Issue edited by: J. Raúl Álvarez-Idaboy, Marcelo Galván, Alberto Vela, Claudio M. Zicovich-Wilson

  1. Cover Image

    1. Top of page
    2. Cover Image
    3. Preface
    4. Full Papers
    1. You have free access to this content
      Cover Image, Volume 112, Issue 21 (pages i–ii)

      Article first published online: 18 SEP 2012 | DOI: 10.1002/qua.24330

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      Aztec symbolism and quantum mechanical concepts are mixed to celebrate the Mexican Theoretical Physical Chemistry Meetings (RMFQT). Two snakes connected by an alligator represent the uncertainly principle of quantum mechanics by contrasting high and low dispersion of the wave packet in momentum and coordinate spaces with the two overlapping circles suggesting a Fourier transform. The large central circle contains symbols indicating heat, momentum and mass transfers as composed of a collection of events and thus related to statistical mechanics. The pictograph in the center of the circle connects to thermodynamics. The red circle and the glyph in the upper left corner enumerate part one of this special issue and the year 2012 of publication. A more detailed cover description by the artist, Renato Lemus, a theoretical chemist at the Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, can be found at the RMFQT site: http://rmfqt.cinvestav.mx.

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      Inside Cover, Volume 112, Issue 21 (pages iii–iv)

      Article first published online: 18 SEP 2012 | DOI: 10.1002/qua.24331

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      Many chemical compounds with important biological and medicinal functions present acid-base equilibriums under physiological conditions. Most of these compounds behave as Brønsted acids (or bases) in aqueous solution and as such their acidity is commonly expressed as pKa. Obtaining reliable pKa values is a very challenging task both for experiments and computational approaches. In the article on page 3449, Annia Galano and coworkers compare the performances of a large set of strategies for accurate calculations of aqueous pKas of relatively large-sized molecules with protonated amino sites. The best identified approaches are then applied to the calculations of the pKas of different neurotransmitters.

  2. Preface

    1. Top of page
    2. Cover Image
    3. Preface
    4. Full Papers
    1. You have free access to this content
      Special Issue: Mexican Theoretical Physical Chemistry Meetings (pages 3439–3440)

      J. Raúl Álvarez-Idaboy, Marcelo Galván, Alberto Vela and Claudio M. Zicovich-Wilson

      Article first published online: 5 SEP 2012 | DOI: 10.1002/qua.24324

  3. Full Papers

    1. Top of page
    2. Cover Image
    3. Preface
    4. Full Papers
    1. On the OH and OOH scavenging activity of 3-methyl-1-pyridin-2-yl-5-pyrazolone: Comparisons with its parent compound, edaravone (pages 3441–3448)

      Adriana Pérez-González and Annia Galano

      Article first published online: 6 MAR 2012 | DOI: 10.1002/qua.24046

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      Pyridyl and edaravone are neuroprotectors with excellent scavenging activity against reactive oxygen species. Therefore, they are predicted to be efficient for preventing, or reducing, oxidative stress and the consequent molecular damage, which has been associated with the onset and development of several illness such as cancer, cardiovascular disorders, atherosclerosis, and several neurological disorders including Parkinson's and Alzheimer's diseases.

    2. First principles calculations of pKa values of amines in aqueous solution: Application to neurotransmitters (pages 3449–3460)

      Aida Mariana Rebollar-Zepeda and Annia Galano

      Article first published online: 28 MAR 2012 | DOI: 10.1002/qua.24048

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      Many chemical compounds with important chemical, biological, and medicinal functions present acid-base equilibriums under physiological conditions. Their acidity is commonly expressed as pKa values. Predicting them with computational techniques with a reasonable accuracy is a very challenging task. A large set of strategies for protonated amino sites is tested in this article and the best performing are used to calculate the pKa's of different neurotransmitters.

    3. Static and dynamic first hyperpolarizabilities from time-dependent auxiliary density perturbation theory (pages 3461–3471)

      Javier Carmona-Espíndola, Roberto Flores-Moreno and Andreas M. Köster

      Article first published online: 4 APR 2012 | DOI: 10.1002/qua.24082

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      New efficient and reliable approach for the calculation of first hyperpolarizabilities from Time-Dependent Auxiliary Density Perturbation Theory (TDADPT). Non-linear optical properties as second harmonic generation (SHG), electro-optical Pockels effect (EOPE), and optical rectification (OR) are now available in an efficient implementation for LDA and GGA functionals.

    4. Free radical scavenging activity of caffeine's metabolites (pages 3472–3478)

      Jorge Rafael León-Carmona and Annia Galano

      Article first published online: 3 APR 2012 | DOI: 10.1002/qua.24084

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      Considering the relatively high amount of caffeine in coffee, significant quantities of its metabolites are anticipated in blood and might be involved in the physiological effects related to coffee consumption, including antioxidant protection. The free radical scavenging activity of paraxanthine (PAR), theobromine (THB), theophylline (THP) and 1-methylxanthine (MXT) was studied and it was found to be higher in non-polar environment than in aqueous solution, and similar to that of their precursor caffeine.

    5. Influence of the methylation degree on the rate constants of the OH addition to alkenes and its temperature dependence (pages 3479–3483)

      Romina Castañeda-Arriaga and J. Raul Alvarez-Idaboy

      Article first published online: 9 APR 2012 | DOI: 10.1002/qua.24109

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      The negative temperature dependence of the alkene + OH reactions is explained by the exponential factor. The reactions occur via a complex mechanism initiated by the reversible formation of a reactant complex, followed by the irreversible, at atmospheric temperatures, addition of OH to the carbon double bond. The negative activation energy is a consequence of the existence of a transition state with lower enthalpy than the isolated reactants.

    6. Nonharmonic vibrational effects in HgClOH: An MP2 Born–Oppenheimer molecular dynamics study (pages 3484–3489)

      Alejandro Ramírez-Solís and Laurent Maron

      Article first published online: 9 APR 2012 | DOI: 10.1002/qua.24123

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      This study reports an MP2 Born–Oppenheimer molecular dynamics study of HgClOH to address the nonharmonic effects which are important in the development of classical interaction potentials. Dynamic effects introduce non-negligible changes to the equilibrium Hg[BOND]O distance and the Cl[BOND]Hg[BOND]O angle which shows rather large (but still harmonic) variations. The largest nonharmonic effects appear for the in-molecular-plane H[BOND]O[BOND]Hg bending and the O[BOND]H stretching modes.

    7. Hydrogen–hydrogen interaction in the LaNiInH4/3 hydride (pages 3490–3497)

      Emilio Orgaz and Andrea Aburto

      Article first published online: 23 APR 2012 | DOI: 10.1002/qua.24139

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      A newly discovered class of quaternary hydrides, RNiInH4/3 (R = La,Ce,Nd) presents exceptionally short, below 2 Å, hydrogen-hydrogen distances. As the H[BOND]H interaction is considered repulsive in nature, such short distances have been so far explained with shielding mechanisms, based on charge redistribution to neighboring atoms or the formation of strong covalent Ni[BOND]H bonds. New all-electrons calculations of LaNiInH4/3 find instead evidence of H[BOND]H attractive interactions and characterize a bonding critical point between the close hydrogen atoms.

    8. The potential energy surface of CO2 from an algebraic approach (pages 3498–3507)

      M. Sánchez-Castellanos, R. Lemus, M. Carvajal and F. Pérez-Bernal

      Article first published online: 5 MAY 2012 | DOI: 10.1002/qua.24141

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      Novel approaches based on unitary algebras to describe the rotovibrational spectra and the molecular potential energy surface of molecules are compared with the results of more computationally demanding ab initio calculation. In the U(2) × U(3) × U(2) algebraic model, the algebraic representation of the Hamiltonian is obtained through the connection between the coordinates and momenta and the generators of the dynamical algebra. The selection of an appropriate set of spectroscopic parameters yields the right potential energy surface for the ground state of the 12C16O2 molecule.

    9. Mechanisms and rate constants in the atmospheric oxidation of saturated esters by hydroxyl radicals: A theoretical study (pages 3508–3515)

      Moises Cordova-Gomez, Cristina Iuga and Juan Raúl Alvarez-Idaboy

      Article first published online: 8 MAY 2012 | DOI: 10.1002/qua.24149

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      The mechanism of the esters + OH reactions is studied. Under atmospheric conditions, these reactions occur via a complex mechanism initiated by the reversible formation of a reactant complex, followed by the irreversible hydrogen abstraction, essentially from carbon atoms in the α position to alkoxy oxygen. The activation of this position is a consequence of the donor ability of such oxygen and the formation of hydrogen bonds in the transition structure.

    10. Is the donor–acceptor electronegativity a good indicator for the surface enhanced Raman scattering (SERS)? (pages 3516–3524)

      Francisco J. Tenorio, Roberto Sato-Berrú, José M. Saniger and Ana Martínez

      Article first published online: 11 MAY 2012 | DOI: 10.1002/qua.24153

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      Two recently described parameters, donor and acceptor electronegativities are evaluated as useful predictors of the charge transfer process and the concomitant chemical enhancement effect. This study finds that the minimum binding energy necessary averages 30 kcal/mol, intensifying as the binding energy becomes more negative accompanied with substantial charge transfer. Thus, these electronegativities are good parameters for the charge transfer process and the contribution of chemical enhancement to surface enhanced Raman scattering.

    11. Tropospheric degradation of ethylene glycol monovinyl and divinyl ethers: A mechanistic and kinetic study (pages 3525–3534)

      Alexander Pérez de la Luz, Cristina Iuga, Juan Raúl Alvarez-Idaboy, Elba Ortíz and Annik Vivier-Bunge

      Article first published online: 15 MAY 2012 | DOI: 10.1002/qua.24159

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      The OH radical reaction with vinyl ethers has been studied using quantum chemistry and computational kinetics. The main channel is OH-addition to the external vinyl carbon atom. OH rate constants of monovinyl and divinyl ethers are very similar, in excellent agreement with experimental results. This effect is attributed to the larger HOMO energy in monovinyl ethers, which is closer to the SOMO of the OH radical, thus favoring a SOMO–HOMO interaction.

    12. The electronic spectrum of AgBr2: Ab initio benchmark calculations on the 2Πu and 2Σu+ charge transfer states including spin-orbit effects (pages 3535–3542)

      A. Ramírez-Solís

      Article first published online: 24 MAY 2012 | DOI: 10.1002/qua.24183

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      The 2Πu and 2Σu+ charge transfer states of AgBr2 have been studied with CASSCF, CASPT2, NEVPT2, and ACPF multireference calculations including spin-orbit effects to study the transition energies, geometries, and vibrational frequencies.

    13. Beyond Wigner's theorems: The role of symmetry equivalences in quantum systems (pages 3543–3551)

      Claudio M. Zicovich-Wilson and Alessandro Erba

      Article first published online: 5 JUN 2012 | DOI: 10.1002/qua.24184

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      Generalized symmetrical objects, not only invariant as usually under symmetry operations, but also equivalent to each other within sets, frequently appear in the quantum chemistry. Their mathematical properties are rigorously proved by theorems that extend the usual role of the irreducible representations in wave-function equations to the more general concept of induced representations.

    14. Electrostatic potential effects of β-cyclodextrin on optical properties of the 4-dimethyl-aminobenzonitrile (pages 3552–3557)

      Guillermo Nieto-Malagón, Julio M. Hernández-Pérez, Rubicelia Vargas and Jorge Garza

      Article first published online: 5 JUN 2012 | DOI: 10.1002/qua.24186

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      Using the time-dependent density functional theory, several examples are shown where the electrostatic potential affects significantly the optical properties of the 4-dimethyl-aminobenzonitrile (DMAB). In particular, an antenna built with the DMAB moiety exhibits different intensity, in the absorption spectrum, when it is inside or outside of the β-cyclodextrin.

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