Polymer Systems as Solid Phase

As described above, polymeric materials provide specific microenvironment in solution which contributes much to construct solar energy conversion systems. Macrohetero-geneous systems constructed from polymers are of great value especially from the practical point of view. 

Components adsorbed on cellulose Initial rate of MV+ accumulation 

Polymer solids also work as a carrier of photochemical reaction components. The irradiation of a cellulose paper after adsorbing EDTA, Ru(bpy)3 and MV2+ induced rapid formation of MV4 in the solid phase (Table 2) 45,48). The quenching experiments showed that a photoinduced electron relay of EDTA Ru(bpy)2 - — MV2+occurs in the solid phase just like in the solution. In this reaction the main path for the MV4 formation is through Ru(bpy)2, and the rate of direct reduction of MV2 by cellulose molecule is very small. Such an electron relay occurred also in a gelatine film 47). 

The reducing power of the MV formed in a solid phase can be transfered to liquid phase. Ru(bpy)3+ and MV2+ were adsorbed in water-swollen chelate resin beads containing iminodiacetic acid (IDA) groups. The irradiation of the beads induced rapid formation of MV in the solid phase through the electron relay of IDA -Z- Ru(bpy)2 MV2 49 .When the beads were irradiated in water contain- 

A photoinduced electron relay system at solid-liquid interface is constructed also by utilizing polymer pendant Ru(bpy)2 +. The irradiation of a mixture of EDTA and water-insoluble polymer complex (Ru(PSt-bpy)(bpy) +, prepared by Eq. (15)) deposited as solid phase in methanol containing MV2+ induced MV 7 formation in the liquid phase 9). The rate of MV formation was 4 pM min-1. As shown in Fig. 14, photoinduced electron transfer occurs from EDTA in the solid to MV2+ in the liquid via Ru(bpy)2 +. The protons and Pt catalyst in the liquid phase brought about H2 evolution. One hour s irradiation of the system gave 9.32 pi H2 after standing 12 h and the turnover number of the Ru complex was 7.6 under this condition. The apparent rate constant of the electron transfer from Ru(bpy)2+ in the solid phase to MV2 + in the liquid was estimated to be higher than that of the entire solution system. The photochemical reduction and oxidation products, i.e., H2 and EDTAox were thus formed separately in different phases. Photoinduced electron relay did not occur in the system where a film of polymer pendant Ru complex separates two aqueous phases of EDTA and MV2 9) (see Fig. 15c). 

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