PHOTOCHEMICAL HOLE-BURNING OF PORPHIN-CROSS-LINKED POLYMETHYLMETHACRYLATE

We synthesized polymethylmethacrylate (PMMA) cross-linked with a tetra phenylporphin (TPP) derivative with four functional groups. The format ion of the cross-linked polymer was confirmed by means of the double d etection technique of gel permeation chromatography. The irreversible broadening, or the spectral diffusion, of the photochemical hole burne d in this cross-linked PMMA is less than in TPP merely dispersed in PM MA. Moreover, the high molecular weight component of the cross-linked PMMA, in which the cross-linkages are expected to be densely formed, e xhibits still less spectral diffusion. From these observations, we con clude that the covalent bonds between the TPP molecule and the host po lymer suppress the changes of the microscopic stereostructure in the v icinity of the TPP molecule and decrease its spectral diffusion at low temperatures.