Oak Ridge National Laboratory , 1 Bethel Valley Road, Oak Ridge, Tennessee 37831, United States.
J Am Chem Soc. 2017 Dec 6;139(48):17350-17358. doi: 10.1021/jacs.7b07318. Epub 2017 Nov 14.
Outer-sphere ion clusters are inferred in many important natural and technological processes, but their mechanisms of assembly and solution structures are difficult to define. Here, we characterize trefoil-shaped outer-sphere lanthanide chloride and nitrate ion clusters in hydrocarbon solutions formed during liquid-liquid extraction with diglycolamide ligands. These are assembled through steric and electrostatic forces, where the anions reside in equidistant "clefts" between coordinating diglycolamide ligands in positions that satisfy both repulsive and attractive ion-ion interactions. Our study shows how sterically directed electrostatic interactions may assemble stable outer-sphere ion clusters in organic solutions, elucidating new strategies for controlling ion cluster assembly and extraction.
外环离子簇在许多重要的自然和技术过程中被推断出来，但它们的组装机制和溶液结构很难确定。在这里，我们描述了在使用二甘醇酰胺配体进行液-液萃取过程中形成的烃溶液中环三叶草形状的外环镧系氯化物和硝酸盐离子簇。这些离子簇通过位阻和静电作用力组装而成，其中阴离子位于配位二甘醇酰胺配体之间等距离的“裂缝”中，其位置既满足排斥相互作用又满足吸引相互作用。我们的研究表明，位阻导向的静电相互作用如何在有机溶液中组装稳定的外环离子簇，为控制离子簇组装和萃取提供了新的策略。
