Time-Resolved EPR Study of Reactive Radical Motion in Cotton: Effects of Confinement
作者:S. N. Batchelor、A. I. Shushin
DOI:10.1021/jp003383w
日期:2001.5.1
2-Hydroxy-2-propyl and benzoyl radicals are created by laser flash photolysis of an α-hydroxyacetophenone in the amorphous regions of dry cotton. The radicals are observed by TREPR spectroscopy and the spectra consist of a liquidlike and crystalline portion. The electron spin polarization pattern is analyzed in detail using 2d and 3d models for the relative diffusive motion and suggest the radical motion has some
2-羟基-2-丙基和苯甲酰基自由基是通过激光闪光光解 α-羟基苯乙酮在干棉的无定形区域中产生的。通过 TREPR 光谱观察到自由基,光谱由液态和结晶部分组成。使用相对扩散运动的 2d 和 3d 模型详细分析了电子自旋极化模式,并表明自由基运动具有一些 2d 特征。反相极化信号的观察表明,大约一半的液态自由基对被困在笼子里。
Quantitative Rate Constants for Radical Reactions in the Nanopores of Cotton
作者:Paula Hunt、David R. Worrall、Frank Wilkinson、Stephen N. Batchelor
DOI:10.1021/ja0201808
日期:2002.7.1
The understanding of radical reactions in nanostructured materials is important for developing new synthetic procedures and controlling degradation reactions. To develop this area, an easy method for measuring quantitative rate constants of some radical reactions in nanostructures is required. A simple method for measuring the rate constant of dye bleaching, kdye, by organic radicals in such materials is introduced, involving the measurement of microsecond bleaching kinetics by diffuse reflectance spectroscopy, following laser flash creation of the radicals. Using wet and dry cotton as model substrates, we obtained kdye of 2-hydroxy-2-propyl and 1-hydroxy-1-cyclohexyl radicals with reactive red 3 and reactive orange 4 and compared them to solution-phase values. Surprisingly, the reactions in cotton follow simple liquid-phase kinetics and are diffusion-controlled. A cage effect in cotton is also found.