Abstract: In this paper, the method of paramagnetic resonance was used to study the pro-cess of formation of ionic free radicals of a new type of porphyrin-anthraquinone compounds through intramolecular electron transfer under photoinduction at a low temperature and the effects of different porphyrin ligands, metal-porphyrin, organic bases axial coordination and solvents on the electron transfer were studied. The experimental results indicate that ESRsignal intensities of porphyrin and metal-porphyrin were increased with time and tend to be stable after 50 min. The signal intensities of PAQ are in the order:H₂TDMAPPQ>H₂(o-NH)PTriPPQ>H₂(p-NH)PPQ, while signal intensity of ZnPAQis greater than that of the corresponding PAQ. The formation rate and quantum yield of ionic free group pair P⁺·-AQ^-· for PAQand ZnPAQin the strong polar solvent(DMF) are lower than those in weak polar solvent(CH₂Cl₂). The axial coordination with piperidine and imidazole increased ESRsignal intensity of ZnTDMAPPQ, which played a promoting role for the charge separation ofZnPAQ. Furthermore, β-carotene may further enhance the charge separation of ZnTDMAP-PQwith positively charged side chain. Therefore, this kind of PAQcompounds are ideal ones for photosynthesis.

Key words: Photoinduction, Porphyrin-anthraquinone compound, Intramolecular electron transfer, Paramagnetic resonance