High-frequency dielectric relaxation behavior up to 20 GHz was investigated for plain (alpha, beta, gamma) and (62 and 100%) methylated cyclodextrins, CDs, in dimethyl sulfoxide, DMSO, solution. Each hydrogen atom of OH groups of the CDs solvated a DMSO molecule for a residence time of 130-180 ps due to the hydrogen bond formation to an oxygen atom of DMSO, and a few DMSO molecules were included in cavities of the CDs for a while similar to the residence time. The overall rotational relaxation modes of solvated CDs were also observed depending on the effective sizes of the solvated CDs.

A complex between a monoclonal antibody for porphyrin and zincporphyrin was utilized to construct an energy conversion system. Monoclonal antibody 2B6 bound meso-tetrakis(4-carboxyphenyl)porphyrin zinc complex (ZnTCPP) with a dissociation constant of 2.1 © 10 ¹8 M. Upon binding the antibody, the lifetime of the excited triplet state of ZnTCPP increased from 0.5 to 1.2 ms. A stable cationic radical of viologen was obtained by irradiating the solution containing the complex of 2B6 with ZnTCPP, methyl viologen (MV 2+ ), and ethylenediaminetetraacetic acid tetrasodium salt (EDTA-4Na) with light. When colloidal platinum was added as a catalyst, photoinduced hydrogen production was observed upon continuous irradiation of visible light. The estimated turnover number of photoinduced hydrogen evolution was 5.0 © 10 ¹3 s ¹1. The catalytic activity of the 2B6ZnTCPP complex on the hydrogen evolution was compared 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 hydrogen production, and the whole antibodyZnTCPP complex led to the efficient hydrogen production.Recently, the design of new energy sources has received much attention because the exhaustion of fossil fuels has become a pressing issue. Furthermore, combustion of fossil fuels causes emission of CO 2 , which has resulted in global warming. Hence, solar energy has become popular due to its limitlessness. Moreover energy derived from hydrogen has received a lot of attention as a clean energy source. Currently, there are many attempts to create energy conversion systems, which convert solar energy into chemical energy.1 On the other hand plants and light harvesting bacteria convert solar energy into chemical energy with high efficiency. 2In the field of artificial energy conversion, hydrogen production systems by photoelectrolysis of water constructed using TiO 2 electrodes have been developed. 3 However, TiO 2 absorbs only UV light, and it cannot use the major part of sunlight. To overcome this problem, dye-sensitized hydrogen-evolution systems have been developed. 4 It is advisable to mimic the energy conversion systems in nature, and the chromophores of in vivo photosynthetic reaction centers are fixed by the protein environment. 5 The distances between electron donors and electron acceptors are noncovalently held under optimum conditions. Recently, non-covalently assembled donoracceptor arrays have been constructed utilizing hydrogen bonding, 6 metal coordination, 7 apoproteins, 8 electrostatic interactions, 9 and supramolecular formations. 10To construct a photoinduced hydrogen production system, a suitable catalyst is necessary to reduce a proton by an electron, which can be obtained by charge separation. In many cases, colloidal platinum has been used as a catalyst for proton reduction.11 To construct an artificial charge-separation system with non-covalently linked electron donors and acceptors, it is fa...

Photoinduced electron transfer between a porphyrin and a new guest cyclodextrin bearing viologen occurs by a supramolecular formation with conformational change of a guest molecule.

Photoinduced electron transfer from porphyrins to electron acceptors was enhanced in the presence of a monoclonal antibody for porphyrin. A hydrogen evolution system was constructed by utilizing the antibody–porphyrin complex, methyl viologen, and colloidal Pt.