Fayer M D
Department of Chemistry, Stanford University, Stanford, California 94305, USA.
Annu Rev Phys Chem. 2009;60:21-38. doi: 10.1146/annurev-physchem-073108-112712.
A wide variety of molecular systems undergo fast structural changes under thermal equilibrium conditions. Such transformations are involved in a vast array of chemical problems. Experimentally measuring equilibrium dynamics is a challenging problem that is at the forefront of chemical research. This review describes ultrafast 2D IR vibrational echo chemical exchange experiments and applies them to several types of molecular systems. The formation and dissociation of organic solute-solvent complexes are directly observed. The dissociation times of 13 complexes, ranging from 4 ps to 140 ps, are shown to obey a relationship that depends on the complex's formation enthalpy. The rate of rotational gauche-trans isomerization around a carbon-carbon single bond is determined for a substituted ethane at room temperature in a low viscosity solvent. The results are used to obtain an approximate isomerization rate for ethane. Finally, the time dependence of a well-defined single structural transformation of a protein is measured.
各种各样的分子系统在热平衡条件下会经历快速的结构变化。此类转变涉及大量化学问题。通过实验测量平衡动力学是一个具有挑战性的问题，处于化学研究的前沿。本综述描述了超快二维红外振动回波化学交换实验，并将其应用于几种分子系统。直接观察到了有机溶质 - 溶剂复合物的形成和解离。展示了13种复合物的解离时间，范围从4皮秒到140皮秒，它们遵循一种依赖于复合物形成焓的关系。在室温下的低粘度溶剂中，测定了一种取代乙烷围绕碳 - 碳单键的旋转顺反异构化速率。结果用于获得乙烷的近似异构化速率。最后，测量了一种蛋白质明确的单一结构转变的时间依赖性。
