Density functional study for discoloration reaction of titanylporphyrin

Titanyl porphyrins are discolored by UV irradiation in the presence of poly[methyl(phenyl)silane] (PMPS). The reactivities of porphyrins and the reactive species generated from the photolysis of polysilane were estimated using the global and local reactivity indices. The high reactivity of silyl radicals and titanyl derivatives was explained well using density functional theory (DFT) and the global reactivity indices. The global reactivity indices suggested that silylene makes no significant contribution to the discoloration reaction. The regioselectivity of the reaction was also discussed with the local reactivity indices and the spectral calculation of the products.