【摘要】 采用纳秒时间分辨的激光闪光光解技术研究了乙腈/水混合溶液中二羟基蒽醌和腺嘌呤或胞嘧啶之间的电子转移反应.在355 nm紫外光作用下,经由系间窜跃产生的三重态二羟基蒽醌与两碱基分别发生电子转移反应,其中碱基作为典型的电子给体.基于测量到的反应瞬态中间体的动力学淬灭速率,两个反应过程被认为分步进行,先电子转移之后发生质子转移反应.通过研究表观淬灭速率与两个碱基浓度的依赖关系,分别得到了两个双分子间电子转移反应的速率常数,分别是9.0×10~8 L/(mol.s)(胞嘧啶)、3.3×10~8 L/(mol.s)(腺嘌呤).更多还原

【Abstract】 Electron transfer（ET） reactions between 1,8-dihydroxyanthraquinone（DHAQ） and two DNA bases,adenine（A） and cytosine（C）,have been investigated in CH₃CN/H₂O solution with nanosecond time-resolved laser flash photolysis.After irradiation at 355 nm,the triplet DHAQ is produced via intersystem crossing and reacts with two nucleobases.ET processes for both reactions have been definitely identified,in which two bases play a significant role of electron donor.Based on the measured decay dynamics of various intermediates and the corresponding quenching rates,an initial ET process followed by a secondary proton-transfer reaction is suggested for both the overall reactions.By plotting the observed quenching rate against the concentration of two DNA bases,the bimolecular quenching rate constants are determined as 9.0xl08 L/（mol-s） for the ³DHAQ*+C reaction and 3.3×l0⁸ L/（mol-s） for the ³DHAQ*+A reaction,respectively.更多还原