Photoinduced Hydrogen-Evolution System with an Antibody–Porphyrin Complex as a Photosensitizer

摘要

A complex between a monoclonal antibody for porphyrin and zinc-porphyrin was utilized to construct an energyconversion system. Monoclonal antibody 2B6 bound meso-tetrakis(4-carboxyphenyl)porphyrin zinc complex (ZnTCPP)with a dissociation constant of 2.1 x 10~(-8)M. Upon binding the antibody, lifetime of excited triplet state ofZnTCPP increased from 0.5 to 1.2 ms. A stable cationic radical of viologen was obtained by irradiating the solutioncontaining the complex of 2B6 with ZnTCPP, methyl viologen (MV~(2+)), and ethylenediaminetetraacetic acid tetrasodiumsalt (EDTA-4Na) with light. When colloidal platinum was added as a catalyst, photoinduced hydrogen production wasobserved upon continuous irradiation of visible light. The estimated turnover number of photoinduced hydrogenevolution was 5.0 x 10~(-3)s~(-1).The catalytic activity of the 2B6-ZnTCPP complex on hydrogen evolution wascompared with that of ZnTCPP alone and the complexes of ZnTCPP with fragments of antibody 2B6 (2B6-H and 2B6-L).The heavy chain of antibody 2B6 mainly contributed to the complex formation with ZnTCPP and the resultant hydrogenproduction, and the whole antibody-ZnTCPP complex led to the efficient hydrogen production.