SUPPRESSION OF SPECTRAL DIFFUSION IN PORPHIN-CROSS-LINKED POLYVINYLALCOHOL OBSERVED BY PHOTOCHEMICAL HOLE-BURNING

We synthesized polyvinylalcohol cross-linked with a four functional po rphin derivative by means of the copolymerization of tetra(vinylphenyl ) porphin and vinylacetate, and the successive saponification. The num ber-average molecular weight of porphin-cross-linked polyvinylalcohol was 8 x 10(4) and the saponification degree was more than 99%. The cro ss-linkage formation was confirmed by the double detection technique o f gel permeation chromatography. By observing the irreversible broaden ing of a photochemical hole under temperature cycles, we found that th e covalent bonds between the porphin derivative and the host polymer, and the hydrogen bonds in the latter cooperatively suppress the struct ural changes in the vicinity of the former to reduce its spectral diff usion.