硝基苯阴离子基的ESR谱的研究

Study on ESR Spectrum of Radical Anion of Nitrobenzene

本文研究了在不同pH值的水溶液中电化学还原产生的硝基苯阴离子基的ESR谱。随pH值下降,硝基苯阴离子基的ESR谱由54条线变为36条线。这种变化主要是硝基苯分子与其阴离子基之间电子交换速度增大,ESR谱线增宽,谱分辨率下降造成的。谱的理论模拟也证明了这一点。交换速度常数在强碱介质中约为3.3×10~6s^(-1)·mol^(-1)·dm^3。

The ESR spectrum of electrogenerated radical anion of nitrobenzene in aqueous solution was studied. The ESR spectrum of the radical anion changed from 54 lines to 36 lines with decreasing pH values. It is because the linewidths of the ESR spectrum increase with decreasing pH values. The simulation of the ESR spectrum verified the above assumption. The electron exchange between the radical anion and the parent molecules causes an increase of the linewidths. The faster electron exchanges, the wider linewidths &re. The rate constant of the electron exchange is about 3.3×10~6 s^(-1)·mol^(-1)·dm^3 in strong basic solution.