Prototypical Allosterism in a Simple Ditopic Ligand: Gas-Phase Topologies of Cucurbit[n]uril· n -Alkylammonium Complexes Controlled by Binding in the Second Site
Prototypical Allosterism in a Simple Ditopic Ligand: Gas-Phase Topologies of Cucurbit[n]uril· n -Alkylammonium Complexes Controlled by Binding in the Second Site
复制标题
简单双位配体中的典型变构现象：由第二位点结合控制的葫芦[n]脲·n-烷基铵配合物的气相拓扑
DOI：
10.1021/acs.jpca.2c01703
复制
发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Dearden, David V.
中科院分区：
文献类型：
--
作者：
Shrestha, Jamir;Porter, Savannah R.;Tinsley, Caleb;Arslanian, Andrew J.;Dearden, David V.
我们采用质谱、离子淌度和计算技术来表征正烷基铵离子与葫芦[5]脲（CB[5]）和葫芦[6]脲（CB[6]）配体在气相中的配合物。对于所有 CB[5] 配合物，非轮烷结构在能量上是优选的并且通过实验观察到。对于 [CB[6]·n-烷基铵]+ 配合物，拟轮烷结构在计算上是有利的，并且在实验中观察到，但在 CB[6] 的相对边缘上添加第二个阳离子（质子、碱金属离子、另一种烷基铵离子或胍）会导致非常不利的空间相互作用，使得正戊基铵和更长的链不再保持穿过 CB[6] 空腔；那么非轮烷拓扑就受到青睐。这提供了这些复合物中负变构相互作用和分子结构转换的一个非常简单的例子。
We have employed mass spectrometry, ion mobility, and computational techniques to characterize complexes ofn-alkylammonium ions with cucurbit[5]uril (CB[5]) and cucurbit[6]uril (CB[6]) ligands in the gas phase. Nonrotaxane structures are energetically preferred and experimentally observed for all CB[5] complexes. Pseudorotaxane structures are computationally favored and experimentally observed for [CB[6]·n-alkylammonium]+complexes, but the addition of a second cation (proton, alkali metal ion, another alkylammonium ion, or guanidinium) on the opposite rim of CB[6] causes sufficiently unfavorable steric interactions thatn-pentylammonium and longer chains no longer remain threaded through the CB[6] cavity; nonrotaxane topologies are then favored. This provides a very simple example of negative allosteric interactions and molecular structure switching in these complexes.