Stabilization of Cucurbituril/Guest Assemblies via Long-Range Coulombic and CH•••O Interactions
Stabilization of Cucurbituril/Guest Assemblies via Long-Range Coulombic and CH•••O Interactions
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DOI：
10.1021/ja4092165
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发表时间：
2014-05-07
影响因子：
15
通讯作者：
Masson, Eric
中科院分区：
文献类型：
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作者：
Joseph, Roymon;Nkrumah, Anna;Masson, Eric
葫芦[n]脲（CB[n]，n = 6-8）通过CH中心点中心点O氢键与金属键合的4 '-取代三联吡啶配体（M = Fe（II）和Ir（III））发生强烈的相互作用，尽管正金属阳离子与CB[n]的羰基化边缘之间存在明显的分离，后者位于金属离子的第二配位层中。虽然水已被证明介导阳离子和CB[n]s在一些组件之间的相互作用，介导的有机配体是前所未有的。识别过程是由非常有利的结合力（高达20.2千卡/摩尔）和非常不利的熵成分（低至-10.2千卡/摩尔）的对比组合驱动的。在CB[8]存在下制备动态低聚物，CB[8]作为金属/三联吡啶络合物之间的“软”非共价连接体，并在其空腔内互连两个4 '-取代基。还观察到CB[8]和带有4 '-（2-萘基）和4'-（2，3，5，6-四氟苯基）取代基的金属/三联吡啶络合物之间的社会自分选，并且可以提供具有交替的Fe（II）和Ir（III）阳离子的组织良好的低聚物。
Cucurbit[n]urils (CB[n], n = 6-8) interact strongly with metal-bound 4'-substituted terpyridine ligands (M = Fe(II) and Ir(III)) via CH center dot center dot center dot O hydrogen bonding, despite significant separation between the positive metallic cation and the carbonylated rim of CB[n], and the location of the latter in the second coordination sphere of the metal ion. While water has been shown to mediate interactions between cations and CB[n]s in some assemblies, mediation by organic ligands is unprecedented. The recognition process is driven by the contrasted combination of extremely favorable binding enthalpies (up to 20.2 kcal/mol) and very unfavorable entropic components (as low as -10.2 kcal/mol). Dynamic oligomers were prepared in the presence of CB[8], which acts as a "soft", noncovalent linker between metal/terpyridine complexes, and interconnects two 4'-substituents inside its cavity. Social self-sorting between CB[8] and metal/terpyridine complexes bearing 4'-(2-naphthyl) and 4'-(2,3,5,6-tetrafluorophenyl) substituents was also observed, and could afford well-organized oligomers with alternating Fe(II) and Ir(III) cations.