ELECTRON EXCHANGE EFFECTS ON ELECTRON TRANSFER DYNAMICS

描述：(逐字摘自申请人的摘要)在自然界中存在 数量惊人的具有活性的金属蛋白和金属酶 场地由多个金属中心组成。在某些情况下，这些金属存在 独立地，而在其他情况下，几个金属中心组成多核 集群。在这样的系统中(例如，非血红素铁氧蛋白和 铁硫蛋白)，多核团簇的电子结构 在很大程度上由存在于 各种金属中心。这项研究项目的目的是阐明 这种多核金属团簇中存在的电子交换本身不能 在生物过程中发挥功能作用：感兴趣的具体目标 就是电子转移。描述了一个模型，其中电子的变化 交换耦合可以与驱动力和 与电子传入和传出电子有关的重组能 交换耦合金属簇。这项研究的目的是 通过实验确定这样的模型在系统中是否可行 哪些金属团簇参与了电子转移途径。 由于金属蛋白的复杂性，电子的鉴定 交换对生物功能的影响需要一些先验知识 人们可能会观察到的可能影响。这类信息完全是 缺乏文学作品。因此，这里描述的研究集中在 人工定制的分子，其中电子和电子的各个方面 分子结构处于实验控制之下。这项研究代表了一种 合成无机化学和物理-无机化学的混合物，其中 合成与详细的光谱研究相结合，从静态的 飞秒时间分辨电子探针的吸收测量 调职。分子间和分子内的电子转移都在 含有氧桥联双铁(III)核的模型配合物以及 双中心铁-硫团簇。制备的分子在其中的变化 系统地介绍了交换耦合(变温探索法) 磁性测量)。然后使用电子转移动力学监测 各种静态和时间分辨光谱(例如，吸收，发射， 和振动)。分子间研究采取经典的形式 Stern-Volmer类型猝灭研究，而分子内动力学 通过使用共价连接的综合定制系统进行了探索 电子供体和电子受体。人们认为，确定是否 电子交换可以在电子转移过程中发挥作用 将代表着理解电子在概念上向前迈出的重要一步 总体上的转移反应，以及对 多核金属簇合物在含过渡金属蛋白质中的作用。

DESCRIPTION: (Verbatim from the Applicant's Abstract) There exist in nature a remarkably large number of metalloproteins and metalloenzymes whose active sites consist of more than one metal center. In some cases these metals exist independently, while in others the several metal centers comprise a polynuclear cluster. In systems such as these (e.g., non-heme iron-oxo proteins and iron-sulfur proteins), the electronic structures of the polynuclear clusters are largely determined by electron exchange interactions that exist amongst the various metal centers. This research project is aimed at elucidating whether or not the electron exchange present in such polynuclear metal clusters can itself play a functional role in biological processes: the specific target of interest is electron transfer. A model is described wherein variations in electron exchange coupling can be linked to changes in both the driving force and reorganization energies associated with electron transfer into and out of an exchange-coupled metal cluster. The objective of this research is to experimentally establish whether or not such a model is viable in systems in which metal clusters are involved in the electron transfer pathway. Due to the complex nature of metalloproteins, identification of electron exchange influences on biological function requires some a priori knowledge of the possible effects one might observe. This type of information is completely lacking in the literature. Studies described herein therefore focus on synthetically tailored molecules in which all aspects of electronic and molecular structure are under experimental control. The research represents a blend of both synthetic inorganic and physical-inorganic chemistries, in which synthesis is coupled with detailed spectroscopic studies ranging from static absorption measurements to femtosecond time-resolved probes of electron transfer. Both inter- and intra-molecular electron transfer is being studied in model complexes containing both the oxo-bridged diiron(III) core as well as two-center iron-sulfur clusters. Molecules are prepared in which variations in exchange coupling are systematically introduced (probed by variable-temperature magnetic measurements). Electron transfer kinetics are then monitored using a variety of static and time-resolved spectroscopies (e.g., absorption, emission, and vibrational). The intermolecular studies take the form of classic Stern-Volmer-type quenching studies, whereas the intramolecular dynamics are probed through synthetically-tailored systems employing covalently linked electron donors and acceptors. It is believed that establishing whether or not electron exchange can play a functional role in electron transfer processes will represent a significant conceptual step forward for understanding electron transfer reactions in general, as well as lending specific insights into the role of polynuclear metal clusters in transition metal-containing proteins.