Benesi-Hildebrand方程的正确性与可靠性(英文)  

Validity and Reliability of Benesi-Hildebrand Method

作　　者：王睿[1] 尉志武[1] 

机构地区：[1]清华大学化学系,生命有机磷化学与化学生物学教育部重点实验室,北京100084

出　　处：《物理化学学报》2007年第9期1353-1359,共7页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(20633080,20675046)资助项目

摘　　要：Benesi-Hildebrand(B-H)方程现被广泛地应用于各种非键作用体系,特别是作用比为1:1型和1:2型的体系.该方程可以用来确定作用体系的平衡常数以及作用比.通过计算机模拟,发现在某些情况下,对于1:2型的作用体系,B-H方程会给出错误的作用比信息.无论是弱的作用体系还是强的作用体系,都可能会出现1:1的B- H方程曲线呈现出线性,同时(或者)1:2的B-H方程曲线呈现出非线性的情况.此外,本文还研究了体系中两种作用物质的初态浓度比对于1:1型作用的平衡常数计算的影响,发现最小的初态浓度比(r_0)等于100是可以确保B-H方程近似条件C_B^0≈C_B成立的安全阈值.当作用很弱的时候,比如说作用的平衡常数K小于25L·mol^(-1)(C_P^0= 4×10^(-4)mol·L^(-1))时,则不需要对最小初态浓度比值r_0进行限制,就可以满足B-H方程的近似条件.通过计算机模拟还分析了文献中提出的两个边界条件.研究表明1/(KC_P^0)≥10可以保证处于平衡状态时的C_B/C_B^0≥0.91.而另一个条件KC_B^0>0.1并不是确保B-H方程近似条件成立的充分条件.Benesi-Hildebrand（B-H）method is a widely used approach for determining the stoichiometry and equilibrium constants of nonbonded interactions,particularly 1：1 and 1：2 interactions.Using computer simulation,it was shown that,under certain conditions,the approach could generate inappropriate stoichiometric conclusions for 1：2 interactions.This problem could occur in the cases of both weak and strong interactions,where the 1：1 B-H plots showed a linear feature and the 1：2 B-H plots showed a nonlinear feature.In addition,effect of the initial concentrations on the accurate evaluation of equilibrium constants of 1：1 interactions was investigated.It was found that the minimum safe concentration ratio r0 between ligand and central species was 100.However,for weak nonbonding interactions,for example K〈25L·mol^-1（CP^0=4×10^-4mol·L^-1）,the ratio r0 has no limitation.Two conditions proposed in literatures for the safe application of the B-H method were examined.It was found that the inequation,1/（KCP^0）≥ 10,was a condition to secure CB/CB^0〉91%.The other inequation,KCB^0〉0.1,was not found to be the safe condition to validate the B-H method.

关 键 词：Benesi-Hildebrand方程 分子间相互作用 平衡常数 作用比 

分 类 号：O642.42[理学—物理化学]