Estudo Computacional das Propriedades Estruturais, Eletrônicas e Ópticas da Bixina, Isonorbixina, Norbixina e Isonorbixina via DFT

Abstract

Bixin and isobixin (C25H30O4), norbixin and isonorbixin (C24H28O4) are pigments found in the seeds of annatto (Bixa orellana L.). Important chemical aspects of these molecules, such as the presence of a conjugated polyene chain, containing a sizeable amount of deslocalized electrons, may present aspects relevant to technological applications such as organic semiconductors and components for building solar cells. The aim of this study was to investigate structural and molecular electronic data using three functionals for method of functional density theory (DFT): B3LYP, CAM B3PLY and M06, and thus select the best functional to reproduce approximately the experimental data from the literature, namely ultraviolet and visible (UV/Vis) spectroscopy. After the calculation process of the molecular structures by the functionals, examined whether structural properties, such as optimized geometry, the bonding length between the atoms and bound length Alternation (BLA). Was imperceptible, for the four molecules, differences of optimized structures in the functionals. Too analyzed whether electronic properties, such as the higher occupied molecular orbitals, the lower unoccupied molecular orbital and the energy gap. The obtained gap values showed that the molecules have a semiconductor character. The theoretical calculations to investigate the UV/Vis spectroscopy, it was pointed out that the CAM B3LYP is the that presents, for the four molecules, near characteristics related to the absorbed wavelength in experimental analyzes.