AN ARTIFICIAL PHOTOSYNTHESIS PORPHYRIN TETRAD MOLECULE FOR PHOTOELECTRIC CONVERSION

A new artificial photosynthesis porphyrin tetrad compound of porphyrin -terephthalic acid ester-viologen-carbarzole (1) was synthesized and c ompared with two triad compounds (2a, 2b) and two diad compounds (3a, 3b) for photoelectric conversion. The absorption and fluorescence spec tra in solution and in binary solvent were investigated; especially th e effects of aggregation on the photophysical properties were studied. A mechanism including photoinduced electron transfer and multistep ch arge separation for tetrad compound was suggested. By using the LB tec hnique, the synthetic molecular devices were prepared with molecules 1 , 2a, 2b, 3a, 3b and the model compound of porphyrin (4b), respectivel y. With only one monolayer of tetrad LB film on the surface of SnO2 co nductive glass, rather high photodriven voltage and current were obtai ned.