利用时间分辨电子自旋共振(TR-ESR)方法,研究了稳定自由基TEMPO和生物 抗氧化剂维生素C(VC)对萘醌(NQ)激发三重态NQ的猝灭机理和猝灭动力学。光解NQ/EG体系, NQ从EG上 抽氢生成萘醌中性自由基NQH 和乙二醇碳自由基CHH(OH)。当体系中加入稳定自由基TEMPO时, TEMPO对NQ 有明显的猝灭作用,猝灭速率常数为 Lmols。 对于NQ/VC/EG-HO溶液, NQ 不仅可以从EG上夺氢,还从VC上夺氢,VC对NQ 也有明显的猝灭作用,猝灭速率常数为 Lmols。TEMPO和VC对NQ 的猝灭反应都受扩散控制。

The reaction mechanism and dynamics of the laser induced excited triplet of 1,4-naphthoquinone (NQ) quenched by TEMPO and biological antioxidant vitamin C (VC) were investigated by means of time resolution electron spin resonance (TR-ESR) method. During the photolysis of NQ/EG (ethylene glycol) solution, NQ abstracts hydrogen atom from solvent molecule EG and the neutral radical NQH and EG ketyl radical CHH(OH) were generated. When TEMPO was added into NQ/EG solution, TEMPO is an effective quencher of NQ and the quenching rate constant is Lmols. For NQ/VC/EG-HO solution, NQ abstracts hydrogen atom not only from solvent EG but also from VC. VC is also an effective quencher of NQ and the quenching rate constant is Lmols. The quenching reactions of NQ by TEMPO and VC are both controlled by diffusion.