Energy Gap and Temperature Dependence of Photoinduced Electron Transfer in Porphyrin-Quinone Cyclophanes
Energy Gap and Temperature Dependence of Photoinduced Electron Transfer in Porphyrin-Quinone Cyclophanes
复制标题
卟啉醌环烷中光致电子转移的能隙和温度依赖性
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
H. Staab
中科院分区：
文献类型：
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作者：
H. Heitele;F. Poellinger;T. Haeberle;M. Michel;H. Staab
我们通过时间分辨荧光衰减测量研究了一系列环烷桥联卟啉-醌系统中的分子内光致电荷分离和重组。电荷分离速率已确定为反应自由能变化、溶剂极性和温度的函数。在一些系统中，观察到长寿命的荧光，这归因于电荷转移态的初始激发态的热重新填充。这种延迟荧光允许计算这些情况下的重组率。在某些溶剂中对特定供体-受体化合物的延迟荧光的观察可作为相应电荷分离的反应自由能(ΔG[sub cs][约等于]0eV)的参考。其他系统中的自由能变化是通过校正各自的卟啉和醌的氧化还原电位的差异来估计的。电子耦合和重组能是通过全局拟合标准速率表达式来确定的，作为实验速率数据的自由能变化的函数。 32 条参考文献、5 张图、4 个标签。
We have investigated intramolecular photoinduced charge separation and recombination in a series of cyclophane-bridged porphyrin-quinone systems by means of time-resolved fluorescence decay measurements. Rates of charge separation have been determined as a function of the free energy change of the reaction, of the polarity of the solvent, and of the temperature. In some systems a long-lived fluorescence is observed which is attributed to a thermal repopulation of the initially excited state from the charge transfer state. This delayed fluorescence allows the calculation of the rate of recombination in these cases. The observation of delayed fluorescence for a particular donor-acceptor compound in some solvent serves as a reference for the reaction free energy of the respective charge separation ([Delta]G[sub cs] [approx equal] 0 eV). The free energy change in other systems is estimated by correcting for differences in the redox potentials of the respective porphyrins and quinones. Electronic couplings and reorganization energies are determined by globally fitting standard rate expressions as a function of the free energy change to the experimental rate data. 32 refs., 5 figs., 4 tabs.