Singlet Oxygen Reactivity in Water-rich Solvent Mixtures
نویسندگان
چکیده
The 3-methylindole (3MI) oxygenation sensitized by psoralen (PSO) has been investigated in 100%, 20% and 5% O 2 -saturated water/ dioxane (H 2 O/Dx) mixtures. The lowering of the O 2 * chemical rate when water (k chem 3MI = 1.4 109 M s) is replaced by deuterated water (k chem 3MI = 1.9 108 M s) suggests that hydrogen abstraction is involved in the rate determining step. A high dependence of the chemical rate constant on water concentration in H 2 O/Dx mixtures was found showing that water molecules are absolutely essential for the success of the 3MI substrate oxidation by O 2 * in water-rich solvent mixtures.
منابع مشابه
Application of Electrochemistry to Determination of Transfer Gibbs Energies and Autoprotolysis Constants for Aqueous Mixtures of Dimethyl Sulfoxide
A practical potentiometric method was applied successfully to experimental electrochemical data in order to determine the autoprotolysis constants (pKap) of water + dimethyl sulfoxide mixtures containing 0-90 % of DMSO by volume at 25° C and 0.1 M ionic strength was maintained in each mixture by NaClO4 solution. The results indicated that water-DMSO mixtures are more basic media than pure water...
متن کاملPhotoreactivity of the fungicide chlorothalonil in aqueous medium.
The photoreactivity of chlorothalonil was studied by means of steady-state irradiation and laser-flash photolysis. Experiments were conducted in water containing acetonitrile as a co-solvent. This fungicide undergoes very slow phototransformation in the first stages of the reaction, but the consumption profile is auto-accelerated. To understand the reaction mechanism, we undertook a detailed st...
متن کاملKinetics of photo-oxidation of Pd(II) complexes with Thiosalycylic acid and1,10-phenanthroline
The complexes of the formula [Pd(phen)(tsa)] and [Pd(tsa)2] (where phen= 1,10-phenanthroline and tsa = dianion of thiosalicylic acid) were synthesized replacing solvent DMSO by water, in order to develop a cleaner chemical synthetic process. Photosensitivity of the synthesized complexes has been studied. A series of photochemical experiments has been performed to investigate the role of these c...
متن کاملPhotosensitized singlet oxygen and its applications
The study of singlet molecular oxygen production and reactivity has emerged as a rich and diverse area with implications in fields ranging from polymer science to cancer therapy. In this review, we address the photophysical properties of singlet oxygen and of the photosensitizers used in its generation. Photosensitizers based on organic molecules and coordination compounds are examined and comp...
متن کاملPhotochemical processes induced by the irradiation of 4-hydroxybenzophenone in different solvents.
The singlet and triplet excited states of 4-hydroxybenzophenone (4BPOH) undergo deprotonation in the presence of water to produce the anionic ground-state, causing fluorescence quenching and photoactivity inhibition. The same process does not take place in an aprotic solvent such as acetonitrile. In acetonitrile, 4BPOH is fluorescent (interestingly, one of its fluorescence peaks overlaps with p...
متن کامل