Eggers Daryl K, Fu Sherry, Ngo Dominic V, Vuong Elizabeth H, Brotin Thierry
Department of Chemistry, San José State University, San José, California 95192-0101, United States.
Université Lyon, Ens de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, Lyon F69342, France.
J Phys Chem B. 2020 Jul 30;124(30):6585-6591. doi: 10.1021/acs.jpcb.0c05354. Epub 2020 Jul 17.
A detailed examination of binding thermodynamics is undertaken for the interaction between rubidium ion and a water-soluble cryptophane molecule using isothermal titration calorimetry. The equilibrium-binding quotient for this host-guest pair decreases with increasing product formation. When analyzed with a thermodynamic framework that considers water explicitly in the governing equation, the shift in equilibrium is ascribed to an unfavorable change in the free energy of solvation upon formation of the inclusion complex. A van't Hoff analysis of the binding data, as well as an observation of aggregation between inclusion complexes, suggests that charge-charge interactions between rubidium ion and the phenolate groups of the cryptophane host provide the driving force for association in water that overcomes a large and unfavorable change in solvent enthalpy.
利用等温滴定量热法对铷离子与水溶性穴番分子之间的相互作用进行了结合热力学的详细研究。该主客体对的平衡结合系数随产物生成量的增加而降低。当用在控制方程中明确考虑水的热力学框架进行分析时，平衡的移动归因于包合物形成时溶剂化自由能的不利变化。对结合数据的范特霍夫分析以及对包合物之间聚集的观察表明，铷离子与穴番主体的酚盐基团之间的电荷 - 电荷相互作用提供了在水中缔合的驱动力，克服了溶剂焓的巨大且不利的变化。
