Abstract: Using pyrrole and p-nitrobenzaldehyde as the starting materials, a novel conjugated product of meso-tetra[4-(benzylideneamino)phenyl] porphyrin(TBAPP) was designed and synthesized after cyclization, reduction and condensation reactions. The product was characterized by UV-Vis, FT-IR, 1H NMR determinations and elemental analysis. In addition, this porphyrin product was also investigated by fluorescence(FL) and electron paramagnetic resonance(EPR) methods. EPR measurement indicated that the prepared porphyrin molecule exhibited radical characteristics. The radicals were produced by the peripheral groups, which could be stabilized by the conjugated π-electrons of porphyrin molecule and detected under normal conditions. Meanwhile the substituent groups around the porphyrin ring contributed different influences on the spectral characters of UV-visible, fluorescence and electron paramagnetic resonance. Compare with its precursor of tetra-aminophenyl porpyrin(TAPP) and its parent compound of tetra-nitrophenyl porpyrin(TNPP), Q bands of the Schiff base phenyl porphyrin TBAPP shifted towards red direction, while its Soret band kept changeless; meanwhile, under excitation at λEx=440 nm, its emission peak appeared at λEm=658 nm, with 5 nm and 9 nm blue shift than those of TAPP and TNPP; furthermore its EPR fine structure was weaker than TAPP and stronger than TNPP.

Key words: porphyrin, Schiff base, electron paramagnetic resonance, fluorescence