Crossover from Superexchange to Hopping as the Mechanism for Photoinduced Charge Transfer in DNA Hairpin Conjugates
作者:Frederick D. Lewis、Huihe Zhu、Pierre Daublain、Torsten Fiebig、Milen Raytchev、Qiang Wang、Vladimir Shafirovich
DOI:10.1021/ja0540831
日期:2006.1.1
The mechanism and dynamics of photoinduced charge separation and charge recombination have been investigated in synthetic DNA hairpins possessing donor and acceptor stilbenes separated by one to seven A:T base pairs. The application of femtosecond broadband pump-probe spectroscopy, nanosecond transient absorption spectroscopy, and picosecond fluorescence decay measurements permits detailed analysis
已经在合成 DNA 发夹中研究了光致电荷分离和电荷重组的机制和动力学,该发夹具有由一到七个 A:T 碱基对分隔的供体和受体芪。飞秒宽带泵浦探针光谱、纳秒瞬态吸收光谱和皮秒荧光衰减测量的应用允许详细分析二苯乙烯受体单线态和电荷分离中间体的形成和衰减。当供体和受体被单个 A:T 碱基对分开时,电荷分离通过单步超交换机制发生。然而,当供体和受体被两个或多个 A:T 碱基对分开时,电荷分离会通过由空穴注入、空穴传输和空穴捕获组成的多步骤过程发生。在这种情况下,空穴到达电子供体比空穴注入桥接 A 束慢。电荷分离(空穴到达)和电荷复合的速率常数取决于供体-受体距离;然而,空穴注入的速率常数与施主-受主距离无关。从超交换到跳跃机制的交叉观察为 DNA 电子转移的分析提供了一个“缺失的环节”,需要重新评估 DNA 中光诱导电子转移的现有文献。空穴注入的速率常数与施主-受主距离无关。从超交换到跳跃机制的交叉观察为