Simultaneous formation of mono- and dications of free-base tetraphenylporphin during photo-oxidation probed by resonance Raman and absorption techniques

We report the simultaneous formation of mono- and dication (known as diacid) radicals during the photo-oxidation of free-base tetraphenylporphin by selective laser excitations using resonance Raman and optical absorption techniques. During the process of photo-oxidation of free-base tetraphenylporphin in carbon tetrachloride, the addition of even a small quantity of tetrahydrofuran leads to the formation of dication along with the monocation radical. A mechanism of simultaneous formation of di- and monocation radicals is proposed.