Conformation-dependent photoinduced hydrogen evolution with Co(II)tetraphenylporphyrin–poly(l-glutamate) complex

Hydrogen production was performed under visible-light and combined UV/visible-light irradiation by using a system consisting of cobalt(II)tetraphenylporphyrin (CoTPP), methylviologen (MV2+), ethylenediaminetetraacetic acid disodium salt and Pt-loaded poly(l-glutamate) (Poly(Glu)) in aqueous decylammonium chloride (DeAC) solution. CoTPP was solubilized in hydrophobic clusters of DeAC induced by its cooperative binding to Poly(Glu). About 0.15 and 3.5 μmol of hydrogen gas were obtained after irradiation for 3 h using visible-light and combined UV/visible-light, respectively. The rate of hydrogen evolution depended on the change in the conformation of Poly(Glu) induced by the cooperative binding with DeAC. An electron was transferred from CoTPP to MV2+ in the Poly(Glu)–DeAC complex system via the singlet state, finally resulting in the hydrogen evolution.