Naruhiko Kaji

Photoinduced hydrogen evolution in micellar system

Photoreduction of viologens by the irradiation of the system containing NADPH, zinc mesotetraphenylporphyrintrisulfonate (Zn-TPPS33−), viologen and colloidal platinum has been investigated in the presence of surfactant micelles. In the presence of either cationic micelles or anionic micelles, a remarkable increase in the accumulation of the reduced form of viologen was observed. The existence of the micelles depressed both the quenching rate of the photoexcited Zn-TPPS33− by viologen and the back reaction rate, recombination rate of the oxidized Zn-TPPS33− and reduced viologen. Compared with both reactions, it was clarified that the recombination rate strongly influenced the viologen reduction rate. The effect of the micelles was explained by the electrostatic effect among the charges of the micellar surface, Zn-TPPS33− and viologen. By the addition of colloidal platinum to the system, photoinduced hydrogen evolution was also studied.

Photoinduced Hydrogen Evolution with Viologen-Linked Porphyrins

Abstract Viologen-linked water-soluble porphyrins with different methylene chain lengths between porphyrin and viologen were synthesized. These compounds were applied to photoinduced hydrogen evolution in a system containing NADPH, viologen-linked porphyrin, and hydrogenase under steady-state irradiation.

Photoinduced hydrogen evolution with a viologen-linked porphyrin

Compounds containing a viologen linked to a porphyrin via a number (n= 2–6) of methylene groups were used in photoinduced hydrogen evolution; hydrogen evolution was observed under steady state irradiation when n= 2.