The influence of temperature on the photo-oxidation rate of tryptophan in the presence of complexes of porphyrins with amphiphilic polymers**This work was supported by the Russian Foundation for Basic Research (project nos. 13-02-12422ofim and 13-02-00934).

Abstract

The influence of temperature on the photocatalytic activity of the complexes of water-soluble porphyrin photosensitizers with amphiphilic polymers, such as poly-4-vinylpyrrolidone, polyethylene oxide, and Pluronic F127 (triblock copolymers of ethylene oxide and propylene oxide) in photo-oxidation reaction of tryptophan in the aqueous solution has been investigated. It has been shown that in the temperature range of 10–40 °C the addition of these polymers increases the activity of triglucamine salt of chlorine e6, tertrasodium salt of tetrasulfophenilporfirina and dimegin. The greatest influence on the rate of photo-oxidation appears to be rendered by the introduction of poly-4-vinylpyrrolidone in the presence of which the value of the rate constant increased by 30–70%. The strongest effect of the polymers is observed at 20–23 °C for dimegin, triglucamine salt of chlorine e6, and for tertrasodium salt of tetrasulfophenilporfirina at 30 °C. We suggest that the effect of the polymer on the effective rate constant relates to the restructuring of the supramolecular structure of polymers during temperature changes.