Dabestani R, Sik R H, Davis D G, Dubay G, Chignell C F
Laboratory of Molecular Biophysics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709.
Photochem Photobiol. 1993 Sep;58(3):367-73. doi: 10.1111/j.1751-1097.1993.tb09576.x.
The photochemistry, photophysics, and photosensitization (Type I and II) of indomethacin (IN) (N-[p-chlorobenzoyl]-5-methoxy-2-methylindole-3-acetic acid) has been studied in a variety of solvents using NMR, high performance liquid chromatography-mass spectroscopy, transient spectroscopy, electron paramagnetic resonance in conjunction with the spin trapping technique, and the direct detection of singlet molecular oxygen (1O2) luminescence. Photodecomposition of IN (lambda ex > 330 nm) in degassed or air-saturated benzene proceeds rapidly to yield a major (2; N-[p-chlorobenzyl]-5-methoxy-2-methyl-3-methylene-indoline) and a minor (3; N-[p-chlorobenzoyl]-5-methoxy-2,3-dimethyl-indole) decarboxylated product and a minor indoline (5; 1-en-5-methoxy-2-methyl-3- methylene-indoline), which is formed by loss of the p-chlorobenzoyl moiety. In air-saturated solvents two minor oxidized products 4 (N-[p-chlorobenzoyl]-5-methoxy-2-methyl-indole-3-aldehyde) and 6 (5-methoxy-2-methyl-indole-3-aldehyde) are also formed. When photolysis was carried out in 18O2-saturated benzene, the oxidized products 4 and 6 contained 18O, indicating that oxidation was mediated by dissolved oxygen in the solvent. In more polar solvents such as acetonitrile or ethanol, photodecomposition is extremely slow and inefficient. Phosphorescence of IN at 77 K shows strong solvent dependence and its emission is greatly reduced as polarity of solvent is increased. Flash excitation of In in degassed ethanol or acetonitrile products no transients. A weak transient is observed at 375 nm in degassed benzene, which is not quenched by oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)
已使用核磁共振、高效液相色谱 - 质谱、瞬态光谱、结合自旋捕获技术的电子顺磁共振以及单重态分子氧（¹O₂）发光的直接检测，在多种溶剂中研究了吲哚美辛（IN）（N - [对氯苯甲酰基] - 5 - 甲氧基 - 2 - 甲基吲哚 - 3 - 乙酸）的光化学、光物理和光敏化（I型和II型）。在脱气或空气饱和的苯中，IN（激发波长λex > 330 nm）的光分解迅速进行，产生一种主要的（2；N - [对氯苄基] - 5 - 甲氧基 - 2 - 甲基 - 3 - 亚甲基 - 吲哚啉）和一种次要的（3；N - [对氯苯甲酰基] - 5 - 甲氧基 - 2,3 - 二甲基 - 吲哚）脱羧产物以及一种次要的吲哚啉（5；1 - 烯 - 5 - 甲氧基 - 2 - 甲基 - 3 - 亚甲基 - 吲哚啉），后者是通过失去对氯苯甲酰基部分形成的。在空气饱和的溶剂中，还会形成两种次要的氧化产物4（N - [对氯苯甲酰基] - 5 - 甲氧基 - 2 - 甲基吲哚 - 3 - 醛）和6（5 - 甲氧基 - 2 - 甲基吲哚 - 3 - 醛）。当在¹⁸O₂饱和的苯中进行光解时，氧化产物4和6含有¹⁸O，表明氧化是由溶剂中溶解的氧介导的。在极性更强的溶剂如乙腈或乙醇中，光分解极其缓慢且效率低下。IN在77 K时的磷光显示出强烈的溶剂依赖性，并且随着溶剂极性的增加其发射大大降低。在脱气的乙醇或乙腈中对In进行闪光激发不产生瞬态信号。在脱气的苯中于375 nm处观察到一个微弱的瞬态信号，该信号不被氧气猝灭。（摘要截断于250字）
