Photoreduction of ferric-tetraphenylporphyrin in oxygen-containing solvents revealed by resonance Raman and absorption spectroscopy

Article abstract of DOI:10.1016/0009-2614(95)01004-S

Photoreduction is observed for Fe(III)(TPP)Cl (TPP is tetraphenylporphyrin) in some oxygen (O)-containing solvents under anaerobic conditions using resonance Raman (RR) and absorption spectroscopy. This process is found to be initiated by visible light in the 390-450 nm region. The coincidence of RR and absorption spectra of photoinduced species and of chemically reduced ones reveals that the final product of photoreduction is the high-spin Fe(II)(TPP)L complex, where L = THF (tetrahydrofuran), DMF(dimethyl formamide) or 1,4-dioxane. Such a photoreduction is not observed under anaerobic conditions for the Fe(III)(TPP)Cl complex in benzene, pyridine or CH2Cl2, nor in the abovementioned solvents under anaerobicconditions. No photoreduction is observed for Fe(III)(OEP)Cl (OEP = octaethylporphyrin). A mechanism for the photoinduced phenomenon observed for Fe(III)(TPP)Cl in O-containing solvents under anaerobic conditions isproposed.