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首次用脉冲辐解时间分辨方法研究了etoposide(VP16)在水溶液中与N_3(SCN)_2~-和e_(aq)~-之间发生的单电子氧化还原反应.测定了 VP16的阴离子自由基、脱质子中性自由基的特征吸收谱;测得VP16与e_(aq)~-,N_3,(SCN)_2~-的绝对反应速率常数分别为2.7×10~9,3.2×10~9和2.5×10~8dm~3·mol~(-1)·s~(-1).研究表明,水溶液中的VP16可为248nm激光光电离,光电离的瞬态产物为阳离子自由基及脱质子中性自由基,并且测定了其酸碱电离的pK值.测得SO_4~-自由基单电子氧化VP16的反应速率常数为2.8 ×10~9dm~3·mol~(-1)·S~(-1).
The single-electron redox reaction of etoposide (VP16) with N_3 (SCN) _2 ~ - and e_ (aq) ~ in aqueous solution was studied for the first time using pulse-resolved radiolysis time-resolved method.An anionic free radical of VP16 was determined, The characteristic absorption spectra of deprotonated neutral free radicals were obtained. The absolute reaction rate constants of VP16 and e_ (aq) ~ -, N_3 and (SCN) _2 ~ were 2.7 × 10 ~ 9, 3.2 × 10 ~ 9 and 2.5 × 10 ~ 8dm ~ 3 · mol -1 · s ~ (-1) .The results showed that the VP16 in aqueous solution was 248nm laser photoionization, the photoionization transient products were cationic radical and deproton-neutral Free radical, and the pK value of its acid - base ionization was measured. The reaction rate constant of SO_4 ~ - radical oxidation was found to be 2.8 × 10 ~ 9dm ~ 3 · mol ~ (-1) · S ~ (-1) ).