Photophysical properties of triphyrin(2.1.1) investigated by time-resolved fluorescence measurements

Excited state dynamics of benzotriphyrin(2.1.1) is investigated by time-resolved fluorescence techniques. The fluorescence quantum yield is found to be 0.005, and the lifetime of the excited state of triphyrin(2.1.1) is found to be 140 ps. Fluorescence anisotropy clearly shows that intramolecular proton transfer does not occur within the excited state lifetime. The short lifetime of the excited state is due to fast internal conversion (IC) from the S1 state, and to the nonplanarity of the macrocycle enhancing IC decay pathways.