Quantitative evaluation of soluble polymeric photosensitizers, 4. Trans-cis isomerization of stilbene photosensitized by polymerbound o- and p-benzyloxybenzaldehyde†

The grafting of o- and p-benzyloxybenzaldehyde onto linear chloromethylated polystyrene is described. The resulting soluble polymeric photosensitizers and their model compounds, o- and p-(p-isopropylbenzyloxy)benzaldehyde, were tested as triplet energy donors against trans-stilbene in benzene solution. Irradiation of the ortho-compounds gives rise to a transformation which has been tentatively attributed to an intramolecular photocyclization. Stern-Volmer constants for the photostable para-compounds were determined. Results for both types of compounds show that the sensitizer efficiency diminishes when it is bound to the polymer.