Time-resolved resonance Raman spectroscopic study on metallotetraphenylporphyrins: Effects of metal sizes

The variation of Jahn-Teller (J-T) distortion imposed on various metallo- t etraphenylporphyrins (MTPPs; M = Zn-II, Pd-II, Pt-II and Rh-III) has been i nvestigated by time-resolved resonance Raman spectroscopy. B-1g and B-2g mo des of the triplet (pi,pi*) States for the heavy-metal porphyrins exhibit t he enhancement of their intensities compared with those of (ZnTPP)-Zn-3-T-I I, while the enhancement of phenyl internal mode is reduced. These results suggest that the J-T distortion becomes manifest as the metal size increase s, and consequently the porphyrin-to-phenyl ring charge transfer in the exc ited triplet state is inhibited.