对一个具有两个同位素结合点的受体进行金属离子协调的反直观静电学
Vidar Aspelin1, Anna Lidskog2, Carlos Solano Arribas2
1Division of Theoretical Chemistry, Department of Chemistry, Lund University, Lund SE 221 00, Sweden.
Journal of the American Chemical Society
|February 10, 2022
概括
这项研究表明,第二个离子比第一个离子更有利地与特罗格的bis- 18冠-6) 类似物结合.
科学领域:
- 超分子化学
- 物理化学
- 计算化学
背景情况:
- 特罗格基的Bis(18-crown-6) 模拟物是一种能够结合离子的宿主分子.
- 了解序列离子结合对于设计选择性分子受体至关重要.
- 之前的研究还没有完全阐明这种系统中连续离子复合的热力学驱动力.
研究的目的:
- 研究连续结合BCETB的离子在水溶液中的热力学.
- 探索控制观察到的结合行为的结构和能量贡献.
- 用理论和计算模型验证实验结果.
主要方法:
- 使用异热定位热量计 (ITC) 来测量结合度和亲和度.
- 连续性的静电理论被用来建模相互作用.
- 复制交换分子动力学 (REMD) 模拟提供了对构造和相互作用的原子尺度见解.
主要成果:
- 观察到一种与直觉相反的热力学特征:第二种离子结合比第一种离子结合更有利 (ΔHbind,2° < ΔHbind,1°).
- 分子动力学模拟证实了实验趋势,并揭示了K+-K+吸引力和离子结合后BCETB形状崩的可能性增加.
- 观察到的趋势在很大程度上独立于 counterion,尽管 thiocyanate 的较弱水分影响了度差异的幅度.
结论:
- 第二个离子的增强结合归因于BCETB的崩形态促进的有利的分子内相互作用.
- 结合离子之间的性吸引力有助于观察到的热力学有利性.
- 这项研究提供了结构,静电和溶解效应的复杂相互作用的基本见解.
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