James Franck Institute and Department of Chemistry, University of Chicago, Chicago, Illinois 60637, USA.
J Phys Chem B. 2011 Feb 24;115(7):1689-92. doi: 10.1021/jp1105696. Epub 2011 Feb 2.
The free energies of reaction or activation for many systems respond in a common fashion to a perturbing parameter, such as the concentration of an "inert" additive. Arrhenius plots as a function of the perturbing parameter display a "'compensation temperature" at which the free energy appears to be independent of the perturber, an entropy-enthalpy compensation process. Thus, as the perturber's concentration varies, Arrhenius plots of the rate constant or equilibrium constant exhibit a rotation about the fixed compensation temperature. While this (isokinetic/isoequilibrium) component of the phenomenon of entropy-enthalpy compensation appears in a huge number of situations of relevance to chemistry, biology, and materials science, statistical mechanical descriptions have been almost completely lacking. We provide the general statistical mechanical basis for solvent induced isokinetic/isoequilibrium entropy-enthalpy compensation in chemical reactions and adsorption, understanding that can be used to control of rate processes and binding constants in diverse applications. The general behavior is illustrated with an analytical solution for the dilute gas limit.
对于许多系统，反应或激活的自由能以一种常见的方式对扰动参数（如“惰性”添加剂的浓度）作出响应。作为扰动参数的函数的 Arrhenius 图显示出在“补偿温度”下，自由能似乎与扰动物无关，这是一个熵-焓补偿过程。因此，随着扰动物浓度的变化，速率常数或平衡常数的 Arrhenius 图围绕固定的补偿温度旋转。虽然这种熵-焓补偿现象的（等动/等平衡）组成部分在与化学、生物学和材料科学相关的大量情况下出现，但统计力学描述几乎完全缺失。我们提供了化学反应和吸附中溶剂诱导的等动/等平衡熵-焓补偿的一般统计力学基础，理解这一点可以用于控制不同应用中的速率过程和结合常数。用稀气体极限的解析解来说明一般行为。
