Solvent Effect on Photosensitized Oxidation of Iodide Ion by Anthracene Sulphonates

Abstract

Iodide ion oxidation by singlet oxygen is found to be influenced by two properties of the solvent. One is the polarity of the solvent and the other is the availability of protons in the solvent. By suitable choice of solvents and solvent mixtures both kinds of effects have been studied. In watermethanol mixtures the reaction is found to be facilitated in more polar medium. In isodielectric media as obtained by mixtures of acetonitrile and methanol the reaction i s repressed with increase in the aprotic component (CH,CN) in the solvent. The same effect is observed in the DMSO-H,O mixtures. In heavy water the reaction rate is doubled and the effect fits well into the proposed kinetic scheme involving singlet oxygen for photosensitized oxidation of I -by anthracene sulphonates.

The DAB-Mn++ cytochemical method revisited: validation of specificity for superoxide.

“…No color change was observed in any tube incubated at 4"C, even after 72 hr. Sodium azide (1 mM), in addition to being a myeloperoxidase inhibitor, is also a quencher of 02('Ag) (k4 = 2.08 x 109 M" sec-') (Gupta and Rohatgi-Mukherjee, 1978). Sodium azide decreased the reaction of Oz('Ag) with DAB in the absence of Mn** but had no observable effect on the reaction of 02(lAg) and DAB in the presence of Mn*+.…”

Lifetime of Singlet Oxygen and Quenching by NaN3 in Mixed Solvents

“…Gupta and Rohatgi-Mukherjee [12] also obtained the same relation for the photooxidation of I -in Me0H-H20 mixed solutions, and proposed a charge-transfer intermediate for the quenching for singlet oxygen by iodide ion. Cohen et al [13] have obtained a linear relation between the log of the quenching rate constant (kq) for triplet benzophenone or fluorenone by amines and 1/e.…”

“…We [14] Young et al [5] and Gupta et al [12] determined the slope of the curve of log ß-1 vs. e _1 in Me0H-H20 mixed solvents. The values are given in Table I with ours.…”

Fluorescence resonance energy transfer: A promising tool for investigation of the interaction between 1-anthracene sulphonate and serum albumins

“…Fig. 1) was synthesized by reducing the corresponding anthraquinone with Zn dust and 20% NaOH solution for 4-6 h described in previous study [1]. The products were treated with active charcoal to remove traces of anthraquinone and other impurities and crystallized four times from water and obtained as a sodium salt.…”

“…The monosulphonate formed on sulphonation makes the molecule water-soluble and, produces interesting fluorescent characteristics, affects its overall symmetry and introduces a negatively charged center in the molecule in aqueous solution [1][2][3][4]. Anthracene sulphonates are amphiphilic in nature with two types of water matrix around the molecules: (i) a hydrogen bonded structure around the hydrophilic SO À 3 groups and (ii) an ice like water structure around the hydrophobic region of the anthracene skeleton.…”