Photophysical properties of N-alkylporphyrins and their metalloporphyrins linked with quinolinium ion in solution

Photophysical properties of N-alkylporphyrins and metalloporphyrins linked with a quinolinium ion were investigated in acetonitrile and propylene glycol. The energy-transfer reaction from the excited singlet state of quinolinium to the bound porphyrin and the electron-transfer reaction from the porphyrin moiety to the excited singlet state of the quinolinium ion occur competitively in the dyad, the former of which is followed by the electron transfer from the excited singlet state of porphyrin to the quinolinium ion. Effect of metal ions on fluorescence is discussed.