Estudo Fotofísico e Espectroscópico da Ftalocianina de Zinco(II) e de dois Derivados Empregando a Teoria do Funcional da Densidade

Abstract

In order to elucidate and understand the photophysical processes of potential photosensitizers based on metal-phthalocyanines of Zn2+ a theoretical study was carried out using methodologies based on the Density Functional Theory (DFT). After obtaining the minimum energy structures, we calculated the singlet and triplet excited states using the time-dependent approach of this theory (TD-DFT). The results showed B and Q bands, typical of the compounds under study, as well as the occurrence of Q-band displacements concomitant with the change of the peripheral substituents, which caused the appearance of a new intermediate band in the spectrum. The study of the molecular orbitals allowed to elucidate how the charge density behaves in these compounds and how the push-pull system influenced it in the excited states. From the analysis of the electronic transitions and the energy levels, it was verified that the intersection between systems (ISC) happens for all the derivatives studied. The elucidation of the deexcitation phenomenon allowed us to infer that the molecules under study have a potential photocatalytic and photodynamic action and that their association with semiconducting oxides is a promising application.