物理化学学报
物理化學學報
물이화학학보
ACTA PHYSICO-CHIMICA SINICA
2007年
9期
1353-1359
,共7页
Benesi-Hildebrand方程%分子间相互作用%平衡常数%作用比
Benesi-Hildebrand方程%分子間相互作用%平衡常數%作用比
Benesi-Hildebrand방정%분자간상호작용%평형상수%작용비
Benesi-Hildebrand method%Molecular interaction%Equilibrium constant%Stoichiometry evaluation
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(r0)等于100是可以确保B-H方程近似条件C0B≈CB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25 L·mol-1(C0P=4×10-4 mol·L-1)时,则不需要对最小初态浓度比值r0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/(KC0P)≥10可以保证处于平衡状态时的CB/C0B≥0.91.而另一个条件KC0B>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)方程現被廣汎地應用于各種非鍵作用體繫,特彆是作用比為1∶1型和1∶2型的體繫.該方程可以用來確定作用體繫的平衡常數以及作用比.通過計算機模擬,髮現在某些情況下,對于1∶2型的作用體繫,B-H方程會給齣錯誤的作用比信息.無論是弱的作用體繫還是彊的作用體繫,都可能會齣現1∶1的B-H方程麯線呈現齣線性,同時(或者)1∶2的B-H方程麯線呈現齣非線性的情況.此外,本文還研究瞭體繫中兩種作用物質的初態濃度比對于1∶1型作用的平衡常數計算的影響,髮現最小的初態濃度比(r0)等于100是可以確保B-H方程近似條件C0B≈CB成立的安全閾值.噹作用很弱的時候,比如說作用的平衡常數K小于25 L·mol-1(C0P=4×10-4 mol·L-1)時,則不需要對最小初態濃度比值r0進行限製,就可以滿足B-H方程的近似條件.通過計算機模擬還分析瞭文獻中提齣的兩箇邊界條件.研究錶明1/(KC0P)≥10可以保證處于平衡狀態時的CB/C0B≥0.91.而另一箇條件KC0B>0.1併不是確保B-H方程近似條件成立的充分條件.
Benesi-Hildebrand(B-H)방정현피엄범지응용우각충비건작용체계,특별시작용비위1∶1형화1∶2형적체계.해방정가이용래학정작용체계적평형상수이급작용비.통과계산궤모의,발현재모사정황하,대우1∶2형적작용체계,B-H방정회급출착오적작용비신식.무론시약적작용체계환시강적작용체계,도가능회출현1∶1적B-H방정곡선정현출선성,동시(혹자)1∶2적B-H방정곡선정현출비선성적정황.차외,본문환연구료체계중량충작용물질적초태농도비대우1∶1형작용적평형상수계산적영향,발현최소적초태농도비(r0)등우100시가이학보B-H방정근사조건C0B≈CB성립적안전역치.당작용흔약적시후,비여설작용적평형상수K소우25 L·mol-1(C0P=4×10-4 mol·L-1)시,칙불수요대최소초태농도비치r0진행한제,취가이만족B-H방정적근사조건.통과계산궤모의환분석료문헌중제출적량개변계조건.연구표명1/(KC0P)≥10가이보증처우평형상태시적CB/C0B≥0.91.이령일개조건KC0B>0.1병불시학보B-H방정근사조건성립적충분조건.
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< 25 L·mol-1 (C0P=4×10-4 mol· 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/(KC0P) ≥ 10, was a condition to secure CB/C0B>91%. The other inequation, KC0B>0.1, was not found to be the safe condition to validate the B-H method.