Metal phthalocyanine-sensitized photoredn. of dimethyl-4-nitrophthalate by ascorbic acid was investigated. The primary photoreaction products are the corresponding amino- and hydroxylamino-compds. The azoxy-compd. is formed by coupling of the nitroso-compd. with hydroxylamino-compd. in the presence of air through secondary dark reaction. The redox potential and fluorescence quantum yield are also determine The variation of the quantum yield for the sensitized photoredn., the relative fluorescence quantum yield and their product with the concentration of nitro-compd. were examined The efficiency of photoredn. sensitized by the singlet and triplet excited states of metal phthalocyanine was calculated Electron transfer from the excited metal phthalocyanine to the nitro-compd. was a primary process in the sensitized photoredn. A necessary requirement for a good sensitizer is that the triplet state is populated in high yield. An alternative way is to design a suitable phthalocyanine skeleton to overcome geminate recombination of the ion pair in order to increase the efficiency of photoredn. sensitized by singlet-excited state of the sensitizer, so as to increase the quantum yield of the total sensitized photoredn.

Key words: NITRO COMPOUNDS, PHOTOSENSITIZATION, QUANTUM YIELDS, ELECTRON TRANSFER, ZINC COMPOUNDS, EXCITED STATE, QUENCHING EFFECTS, PHOTO REDUCTION, FLUORESCENCE, TRIPLET