The effect of imidazole on the singlet oxygen quantum yield of sinoporphyrin sodium

Abstract In this paper, the effect of imidazole on the singlet oxygen quantum yield (ΦΔ) of sinoporphyrin sodium (DVDMS) was studied. A relative method was used to measure ΦΔ with Rose Bengal (RB) as the reference and 1,3-diphenylisobenzofuran (DPBF) as the singlet oxygen trapping reagent. It can be found that ΦΔ of DVDMS decreased with the increment of imidazole concentration, and kept 0.33 after the imidazole concentration was above 0.26 M. The process of 1O2 generation and optical properties of DVDMS in different imidazole concentrations were studied to analyze the reason for the above behavior. The invariability of UV–vis absorption and photoluminescence spectra suggested that the reduction of ΦΔ was attributed to the decrease of interaction between DVDMS and O2, which was caused by the surrounding of imidazole on DVDMS. For efficient implementation of PDT, it is necessary to identify the factors that may reduce the effect of PDT.