Photophysical and electrochemical properties of twotrans-A2B-corroles: differences between phenyl or pyrenyl groups at themeso-10 position

The present study reports on the optical and photophysical properties oftrans-A(2)B-corroles possessing pyrenyl units attached at themeso-10-position and compares them with those of modeltrans-A(2)B-corroles having phenyl substituents at that position. In contrast to the modelmeso-substituted corrole, the new pyrenyl-corrole shows slightly red-shifted absorption bands and blue-shifted emission, slightly higher fluorescence quantum yield, and more importantly, it shows better photo-stability under white-light illumination. Theoretical calculations were used to determine the electronic transitions and geometries of the singlet and triplet excited states (TD-DFT and NTO). Moreover, we demonstrate that the pyrenyl-corrole in analogy to previously studied model corroles is able to generate reactive oxygen species (ROS) under visible light using photo-degradation of 1,3-diphenylisobenzofuran (DBPF), a singlet oxygen quencher, and EPR spectroscopy allied with the spin-trapping method is used for identifying singlet oxygen species. The results show that the pyrenyl unit attached at themeso-10-position of the corrole increases the photo-stability and efficiency in ROS generation compared to the phenyl substituent.