Liu Y, Sturtevant J M
Department of Chemistry, Yale University, New Haven, Connecticut 06520, USA.
Protein Sci. 1995 Dec;4(12):2559-61. doi: 10.1002/pro.5560041212.
Isothermal calorimetric titration of 18-crown-6 ether with BaCl2 in pure aqueous solution over the temperature range 7-40 degrees C gives precise binding constants and enthalpy changes. Nonlinear least-squares fitting of the binding constants to the integrated van't Hoff equation, including a temperature-independent change in heat capacity, leads to van't Hoff enthalpies that differ significantly from the observed calorimetric enthalpies. This perplexing discrepancy appears at present to be very widely occurring.
在7至40摄氏度的温度范围内，在纯水溶液中用氯化钡对18 - 冠 - 6醚进行等温滴定量热法，可得到精确的结合常数和焓变。将结合常数对积分范特霍夫方程进行非线性最小二乘拟合，包括与温度无关的热容变化，得到的范特霍夫焓与观察到的量热焓有显著差异。目前看来，这种令人困惑的差异非常普遍。
