SOLUBLE POLYMERS WITH PENDANT THIONINE GROUPS - SYNTHESIS AND EVALUATION AS SINGLET OXYGEN PHOTOSENSITIZERS

Thionine (1) has been covalently bound to linear copoly(styrene-p-viny lbenzyl chloride) and to linear copoly(acrylic acid-2-ethylhexyl acryl ate). The resulting polymeric dyes, purified by ultrafiltration, prese nt quantum yields of singlet oxygen generation in dimethylformamide so lution lower than their corresponding low-molecular-weight models thio nine hydrochloride (1.HCI) and N(3)-acetylthionine (Ac-1), the decreas e being more pronounced in the case of the polystyrene-dye photosensit izer. High chromophore concentrations within the volume encompassed by each macromolecule in the solution can explain this fall in efficienc y. The free dyes thionine hydrochloride and its hydrolysis products th ionoline (2) and thionol (3) behave as good singlet oxygen generators, with quantum yields of 0.71, 0.62, and 0.63, respectively. (C) 1993 J ohn Wiley & Sons, Inc.