Estudo de primeiros princípios de propriedades fotofísicas de macrociclos tetrapirrólicos

Abstract

Tetrapyrrolic macrocycles are very well known photosensitive molecules, absorbing in the visible and ultra-violet (UV-vis) light range. Their efficiency in optical processes as well as the possibility of tuning their absorption behavior by simply modifying the substituents make them promising candidates for dyed sensitized solar cells (DSSC) and photocatalytic reactions. The density functional theory (DFT) through first principles calculations has been used to study the optical and redox properties of tetrapyrrolic macrocycles. Across the theses, we have implemented DFT calculations to assess the photophysical aspects of porphyrin, corrin, chlorin and corrole rings with different substituents. Our results indicate the absorption spectra of these molecules to be in the UV-vis range. Additionally, we have found that both porphyrin and corrole rings attached with electron-acceptor substituents exhibit redox potentials that satisfies the water breaking reaction necessary for the photocatalysis process. For the corrin- and chlorin-substituted chlorophyll, our results revealed their susceptibility to photocatalytic and absorption modifications due to the substituent choices. The results for the corrole-fullerene (C60) dyads also reveal the possibility of tuning their optical absorbance through modifications in the positions at which the fullerene is attached. Markedly, the redox properties of the β−substituted corrole-fullerene indicates promising photocatalytic applications for these compounds.