Estudo teórico de propriedades elétricas de derivados de retinal em solução

• Autor(a) principal: Adriano Júnior, Luizmar
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• dARK ID: ark:/38995/0013000004v50
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/3583
• topic: Derivados de retinal; Efeitos de solvente; Propriedades elétricas; Retinal derivatives; Solvent effects; Electric properties; FISICA::FISICA GERAL

In this work we study the dipole moment, linear polarizability and first hiperpolarizability of 09cis, 11cis, 13cis and all-trans retinal derivatives in the gaseous phase and in different solvents. The solvent effects were modelled using the sequential Quantum Mechanics/Molecular Mechanics – S-QM/MM – methodology and the electric properties were calculated numerically with the finite field method. We use an average solvent electrostatic configuration – ASEC – to obtain the same statistical average with just one quantum mechanics calculation, instead of performing several quantum mechanics calculations for each one of the configurations of liquid. The second-order Møller–Plesset perturbation theory – MP2 – were used to describe the electronic structure. Our results show that the presence of the solvent increases the first hyperpolarizability of molecules of retinal [retinoic acid] by 17%-120% [5%-65%] when compared with corresponding gas phase results. It is found, in addition, that the dipole moment and the first hyperpolarizability are particularly affected by changes in the polarity and nature of solvent. A comparative analysis between cis and trans retinal derivatives shows that the isomerization effects have a marked influence on both the dipole moment and the average first hyperpolarizability.