Time-Resolved Spectroscopic Studies of Hydrogen-Bonded Molecular Complexes

匹兹堡大学的David Waldeck教授得到了理论与计算化学项目的资助，继续他关于氢键分子复合物的时间分辨光谱研究。Waldeck先前的工作涉及使用光学外差偏振光谱和荧光去偏振测量旋转扩散。目前的项目扩展了这项工作，以更深入地了解氢键配合物和分子间键合的动力学。他将使用相同的实验技术，偏振光谱和荧光去极化，来研究氢键客体分子的迁移率和柔韧性作为结合焓和拓扑结构的函数。将在三氯甲烷和二甲基亚砜等非缔合但偶极有机溶剂中对各种主/客体系统进行实验研究，并与理论进行比较。本研究的主要目标是了解氢键的位置和强度如何决定分子间氢键配合物的柔韧性，并对这种配合物的动力学有更深入的了解。这些研究很重要，因为它们应该阐明动力学的各个方面，这些方面在化学和生物学中很重要。在生物学中，宿主中客体分子的灵活性可能对生物分子的结合和酶的活性至关重要。在化学中，当分子片段在电位中运动时，分子片段与溶剂之间发生的摩擦耦合是理解溶剂对化学反应的动力学影响的核心。Waldeck正在进行的研究将对这些更大、更复杂的问题产生直接影响。

Professor David Waldeck, University of Pittsburgh, is supported by a grant from the Theoretical and Computational Chemistry Program to continue his research involving time-resolved spectroscopic studies of hydrogen-bonded molecular complexes. Waldeck's prior work involved measurements of rotational diffusion using optically heterodyned polarization spectroscopy and fluorescence depolarization. The current project extends this work to obtain a deeper understanding the dynamics of hydrogen bonded complexes and intermolecular bonding. He will use the same experimental techniques, polarization spectroscopy and fluorescence depolarization, to study the mobility and flexibility of hydrogen bonded guest molecules as a function of binding enthalpy and topology. Experimental studies will be conducted on a variety of host/guest systems in unassociated but dipolar organic solvents such as trichloro methane and dimethyl sulphoxide, and comparisons made with theory. The principal goal of the research is to understand how the position and strength of hydrogen bonds determine the flexibility of intermolecular hydrogen bonded complexes, and to gain a deeper understanding of the dynamics of such complexes. These studies are important because they should elucidate aspects of dynamics which are important in chemistry and biology. In biology, the flexibility of a guest molecule in a host is likely to be of critical importance for the binding of biological molecules and for enzyme activity. In chemistry, the frictional coupling which occurs between a molecular moiety and a solvent when the moiety is moving in a potential is at the core of understanding the dynamical influence of a solvent on a chemical reaction. The studies being undertaken by Waldeck will have a direct bearing on these larger and more complex issues.