Estudo teórico das propriedades fotocatalíticas das ftalocianinas

Abstract

Phtalocyanines constitute a class of aromatic molecules that have been used by industry mainly as dyes or pigments. More recently different Phtalocyanine derivatives were synthesized and are been employed to fabricate electronic devices. The use of these molecules in devices requires the fine tuning of their electronic properties in order to the molecule be functional, in a process named functionalization. There are several forms to functionalize the Phtalocyanines, among them the adsorption of a metallic atom at their central ring. In this work we make an analysis on the effect of the adsorption of different metallic ions (Co, Cu, Fe, Ni, Zn) at the central ring of the Phtalocyanine. The density functional theory and its time dependent version have been used to determine the redox potentials and absorption spectra. Absorbance spectra were used in a time dependent version of DFT, TD-DFT (Time Dependent Density Functional Theory). Add a free base phthalocyanine structure by adding a level to its center sensing a shift in the absorption bands for the smallest wavelengths, except for the iron, because the internal side of iron is an unfolding of the absorption band. By adding a presence of the solvent, we notice a shift to a region of greater wavelength. It was noted that the efficiency in dichloromethane was higher than insidated by the presence of acetonitrile. In order to obtain the oxidation and reduction advantages, it is necessary to compare with the metal, with a Cobalt phthalocyanine being turned off for a photocatalysis of water molecule breakdown, taking into account all the requirements, while most metalophthalins revealed. A difference was found between the reduction and oxidation potentials obtained with acetonitrile and dichloromethane.