Porphyrins with fluorenyl and fluorenone pendant arms

Porphyrins with fluorenyl and fluorenone groups at the meso-positions have been synthesized and characterized, and the fluorescence of these compounds has been studied. Following selective excitation of the pendant arms with UV light, we show that the energy is transferred to the porphyrin core and reemitted as red light. In comparison to tetraphenylporphyrin, the luminescence properties are markedly improved. The fluorescence quantum yields of tetrafluorenylporphyrin 1 and tetrafluorenoneporphyrin 2 are 0.22 and 0.25, respectively.