Solvent effects on the photochemistry of dimethyl sulfoxide–Cl complexes studied by combined pulse radiolysis and laser flash photolysis

Abstract

Photolysis of complexes of dimethyl sulfoxide (DMSO) with chlorine atoms results in rapid and permanent photobleaching which may be due to intramolecular hydrogen abstraction. The effects of solvent polarity were examined in a wide variety of DMSO-carbon tetrachloride mixed solvents. The quantum yields of photobleaching decreased from 0.27 to 0.08 as the solvent polarity increased, while significant changes were observed in the low DMSO concentration range (< 0.2 mol dm -3 ). This cannot be accounted for by simple solvent polarity effects. The effects of polar and nonpolar additives were also examined and it is concluded that the specific solvation effect of DMSO was the main cause of the significant change in the quantum yields in the low concentration range of DMSO.

Formation and photochemistry of organic sulfur compound–chlorine atom complexes

“…Photobleaching was also observed after radiolysis and photolysis of sulfur compounds in 1,2-dichloroethane (1,2-DCE). These permanent photobleaching can be assigned to the intramolecular hydrogen abstraction as observed for DMSO _ Cl complexes (Sumiyoshi et al, 2006a).…”

“…Photochemical studies of dimethyl sulfoxide _ chlorine atom complexes (DMSO _ Cl) produced in DMSO/CCl 4 mixed solvents have shown that the photolysis of the complex results in rapid and irreversible photobleaching due to intramolecular hydrogen abstraction (Sumiyoshi et al, 2006a). The quantum yields of the photobleaching decreased with increasing solvent polarity as the DMSO concentration increased.…”

Photobleaching of Sn(IV) chlorine e6 dichloride trisodium salt in different environments

“…In comparison, the absorption in both Soret and Q band, which was accompanied with red shift in the presence of 10% FBS and 1% BSA, was almost lower than the absorption of neat buffer at the same photosensitizer concentration. The slight reduction of the absorption is probably due to the binding among photosensitizer molecules and the protein molecules, which leads to more aggregation (Sumiyoshi et al, 2006). The presence of more proteins in the solvent leads to more reduction in absorption spectra as shown in Figure 2, where the absorption spectrum in 10% FBS is less than in 1% BSA.…”

“…The solvent has some responsibility for this change. The effect of solvents on photobleaching is not yet clear but some researchers show that the polarity of the solvent could play an important role in photobleaching (Sumiyoshi et al, 2006).…”

Pulse radiolysis studies of the reactions of bromine atoms and dimethyl sulfoxide–bromine atom complexes with alcohols

“…The extinction coefficient of the DMSO _ Cl complexes was determined as (7800±50) M -1 cm -1 at λ max =400 nm in the previous study (Sumiyoshi et al, 2005a(Sumiyoshi et al, , 2006.…”