化学
光化学
闪光光解
反应速率常数
酰亚胺
猝灭(荧光)
电子转移
乙烯基
激发态
二苯甲酮
动力学
荧光
有机化学
量子力学
物理
核物理学
作者
Joy E. Rogers and,Lisa A. Kelly
摘要
The rate constants for electron transfer from guanosine 5‘-monophosphate (GMP), adenosine 5‘-monophosphate (AMP), cytidine 5‘-monophosphate (CMP), and thymidine 5‘-monophosphate (TMP) to the triplet excited states of N-(3-propanol)-1,8-naphthalimide (NI), N,N ‘-(3-propanol)-1,4,5,8-naphthaldiimide (NDI), and N,N ‘-(3-propanol)-3,3‘,4,4‘-benzophenonediimide (BPDI) have been determined in 1:1 H2O/CH3CN solution. Upon 355-nm (8 ns) laser flash excitation of each of the imide or diimides in solution, the triplet states decayed by first-order kinetics under conditions of low excitation energy. Photoinduced electron transfer to the lowest electronically excited triplet state of N-(3-propanol)-1,8-naphthalimide from GMP occurred with a rate constant of 2.0 × 107 M-1 s-1. Electron-transfer quenching by the other nucleotides was almost 2 orders of magnitude slower. In the case of BPDI, photooxidation rate constants ranged from 2.3 × 108 M-1 s-1 for quenching by CMP to 1.1 × 109 M-1 s-1 by GMP. In all cases, the imide radical anion was observed by laser flash photolysis, and the yields were quantified. From these investigations, nucleotide oxidation by the triplet state of a series of redox-active photosensitizers has been demonstrated. The results represent a systematic study of nucleotide oxidation by the triplet states of a series of structurally related organic photosensitizers in which the reduction potential can be tuned by ca. 800 mV. The greater than 100-fold variation in bimolecular rate constants for oxidation of base monophosphates by these photosensitizers offers the prospect of kinetic “selectivity” of oxidative damage in random-sequence DNA.
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