Porphyrin photosensitizers solubilized with pluronics in the oxidation of tryptophan

Abstract

It was shown that water-insoluble porphyrins solubilized with pluronics (ternary block copolymers of ethylene oxide and propylene oxide) efficiently transfer photoexcitation energy to molecular oxygen dissolved in aqueous media to excite it into the singlet state, which is active in oxidizing organic substrates. It was established that the degree of solubilization of porphyrin photosensitizers (PPSs) γ defined as the proportion of PPS molecules passed into the aqueous phase in the dissolution of formed films depends on a single parameter, the initial ratio between the porphyrin and pluronic molar concentrations q. γ = γ(q) dependences for the solubilization of dissimilar water-insoluble porphyrins were analyzed. It was shown that the behavior of all the obtained γ = γ(q) dependences is changed at a characteristic value q max: when q š q max, γ ∼ 1, and, when q ≥ ?qmax, the degree of solubilization decreases. It was concluded that solubilized porphyrins are efficient photosensitizers in the oxidation of organic substrates (tryptophan).