Kinetic and Thermodynamic Studies of Long Distance Electron Transfer Reactions

将对控制电子转移反应的速度和效率的因素进行调查。通过测量光致电荷分离速率常数和发射光谱随温度的变化以及计算电子转移自由能来评价间隔基团分离给体和受体基团的效果。皮秒光量热法将被用来评估电子转移时发生的热焓和体积变化。最后，我们将研究结构刚性分子中通过溶剂的电子耦合及其对电子转移的影响。将分析转移速率常数、电子耦合矩阵元素和溶剂能带结构之间的关联。电子的快速转移是大量化学反应中常见的一个过程。利用有机动力学项目的这笔资金，布朗大学的马修·齐姆特教授将研究控制电子转移过程速率的因素，这些过程在万亿分之一秒内完成。影响电子转移的参数将使用专门设计的分子来研究，以便既能很好地定义给体和受体基团之间的距离，又能很好地确定中间原子的身份和位置。这项研究的结果可能使设计最大限度提高电子转移效率的分子体系成为可能。

An investigation of the factors which govern the rate and efficiency of electron transfer reactions will be conducted. The effect of spacers separating donor and acceptor groups will be evaluated by measuring photoinduced charge separation rate constants and emission spectra as a function of temperature and calculating free energies of electron transfer. Picosecond photocalorimetry will be used to evaluate enthalpy and volume changes which occur upon electron transfer. Finally, through-solvent electron coupling and its impact upon electron transfer will be investigated in structurally rigid molecules. Correlations between transfer rate constants, electronic coupling matrix elements, and solvent band structure will be analyzed. %%% A process which is common to a large number of chemical reactions is the rapid transfer of electrons. With this grant from the Organic Dynamics Program, Profssor Matthew Zimmt of Brown University will investigate the factors which govern the rate of electron transfer processes which are complete within a few trillionths of a second. The parameters which influence electron transfer will be investigated using molecules specially designed so that both the distance between donor and acceptor groups and the identity and positions of the intervening atoms are well-defined. The results of the study may make it possible to design molecular systems which will maximize electron transfer efficiency.