Advanced search
Start date
Betweenand
Related content
(Reference retrieved automatically from SciELO through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

A computational study of substituted flavylium salts and their quinonoidal conjugate-bases: S0 -> S1 electronic transition, absolute pKa and reduction potential calculations by DFT and semiempirical methods

Full text
Author(s):
Adilson A. Freitas [1] ; K. Shimizu [2] ; Luís G. Dias [3] ; Frank H. Quina [4]
Total Authors: 4
Affiliation:
[1] Universidade Técnica de Lisboa. Instituto Superior Técnico - Portugal
[2] Universidade Técnica de Lisboa. Instituto Superior Técnico - Portugal
[3] Universidade de São Paulo. Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto. Departamento de Química - Brasil
[4] Universidade de São Paulo. Instituto de Química - Brasil
Total Affiliations: 4
Document type: Journal article
Source: Journal of the Brazilian Chemical Society; v. 18, n. 8, p. 1537-1546, 2007-00-00.
Abstract

The electronic transitions for flavylium cations and quinonoidal bases of 17 substituted flavylium salts have been studied at semiempirical and DFT (density functional theory) levels. Solvent effect on electronic spectra was included by Polarizable Continuum Model, PCM. We assigned longest-wavelength absorption maxima to HOMO -> LUMO transition. Both levels of theory gave good results for electronic transitions of flavylium cations whereas only TDDFT-PCM calculations could be used for electronic transitions of their quinonoidal bases. We also performed absolute pKa calculations of nine flavylium salts at DFT level. The pKa calculated values by our PCM parameterization gave excellent results with mean absolute deviation less than a half of one pKa unit. One-electron reduction potentials were carried out for 5 flavylium cations at DFT level. The theoretical results found were in good agreement with experimental values after adjustment for a systematic deviation. (AU)