Resonance Raman spectra of metal-free porphin and some prophyrins

Resonance Raman spectra have been obtained of solid porphin, protoporphyrin IX, mesoporphyrin IX dimethyl ester and the two position isomers of Coproporphyrin tetramethyl esters 3 and 4, using the rotating Raman cell technique. The various sidechains in different porphyrins have very pronounced effects on the Raman spectrum of porphin. The usefulness of the resonance Raman technique in the identification of substituted porphins and closely related position isomers is demonstrated.