Absolute and relative binding affinity of cucurbit[7] uril towards a series of cationic guests
Absolute and relative binding affinity of cucurbit[7] uril towards a series of cationic guests
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DOI：
10.1080/10610278.2013.852674
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发表时间：
2014-03-18
影响因子：
3.3
通讯作者：
Isaacs, Lyle
中科院分区：
文献类型：
--
作者：
Cao, Liping;Isaacs, Lyle
我们通过在100 mM Na 3 PO 4缓冲D2 O中的H-1 NMR竞争实验确定了客体1-19对葫芦[7]脲的相对结合常数（K-rel）。在这些实验中，我们使用客体11作为参考客体，因为它与CB[7]的结合力很强，并且具有有利的光谱特性（例如，NMR时标上的缓慢交换和关键质子的不同共振）。为了将测定的K-rel值转化为绝对结合常数，我们用CB[7]进行1的直接UV-可见滴定以测定CB[7]根1的K-a。K-rel和K-a的测定值的趋势进行了讨论，相对于缓冲液中的金属离子的浓度的重要性，位于门户或CB[7]腔内部的羟基的影响，客体的几何形状（例如区域异构体），客体C原子的数目和次级静电相互作用。
We determined the relative binding constants (K-rel) for guests 1-19 towards cucurbit[7]uril by H-1 NMR competition experiments in 100 mM Na3PO4-buffered D2O. In these experiments, we use guest 11 as the reference guest because of its strong binding towards CB[7] and its advantageous spectroscopic properties (e.g. slow exchange on NMR timescale and distinct resonances for key protons). To convert the determined K-rel values to absolute binding constants, we performed a direct UV-vis titration of 1 with CB[7] to determine K-a for CB[7]root 1. The trends in the determined values of K-rel and K-a are discussed with respect to the importance of the concentration of metal ions in the buffer, the influence of hydroxyl groups located at the portals or inside the CB[7] cavity, geometry of the guest (e.g. regioisomers), the number of guest C atoms and secondary electrostatic interactions.