Studies on the Protein- Chlorophyll Artificial Complexes Bearing Hydrogen-Evolving Function

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In this work, the photoinduced hydrogen production with systems containing water insoluble chlorophyll a (Chla) or Co(II)tetraphenylporphyrin (CoTPP), and also methylviologen, platinum colloidal catalyst and ethylenediaminetetraacetic acid was investigated. Chla and CoTPP were dissolved in aqueous poly (L-glutamate) and decylammonium chloride (DeAC) surfactant solutions.The systems were characterized in the absence and presence of methylviologen using spectroscopic methods such as circular dichroism, absorption spectroscopy, Fourier-transformed infra-red spectroscopy, steady state fluorescence spectroscopy and fluorescence lifetime measurements.The spectroscopic studies indicate that Chla and CoTPP are incorporated into poly(L-glutamate)-surfactant complexes accompanying a conformation change from the random coil to the α-helix of poly(L-glutamate). A conformation- dependent electron transfer also occurs between Chla or CoTPP and methylviologen.A drastic increase in the evolution rate of hydrogen occurred for both photocatalysts (Chla and CoTPP) under the visible-light irradiation in the presence of the poly (L-glutamate)-DeAC complex than in the absence of the complex.We also observed the drastic synergy effect of titanium oxide (a typical semiconductor photocatalyst) and graphite silica (one of natural minerals) or single-walled carbon nanotube for the production of hydrogen gas in water-alcohol mixtures.We are now challenging to the practical hydrogen production on the basis of the present results.