Jayaraj Nithyanandhan, Zhao Yaopeng, Parthasarathy Anand, Porel Mintu, Liu Robert S H, Ramamurthy V
Department of Chemistry, University of Miami, Coral Gables, Florida 33124, USA.
Langmuir. 2009 Sep 15;25(18):10575-86. doi: 10.1021/la901367k.
Factors that govern inclusion of organic molecules within octa acid (OA), a synthetic deep cavity cavitand, have been delineated by examining the complexation behavior of a number of organic molecules with varying dimensions and functionalities with OA. The formation of two types of complexes has been noted: the one which we call cavitandplex is a partially open complex in which a part of the guest molecule remains exposed to water, and the other termed capsuleplex is formed through assembly of two OA molecules. In capsuleplex, the guest is protected from water. Generally, guest molecules that possess ionic head groups form cavitandplex, and all others form capsuleplex. Capsuleplex may contain one or two guest molecules within the capsule. Small organic molecules (<10 A in length) may form both 2:1 and 2:2 capsuleplex, while longer ones (>12 A) preferentially form 2:1 capsuleplex. Extensive 1H NMR experiments have been carried out to characterize host-guest complexes. In the absence of the guest, OA tends to aggregate in water. The extent of aggregation depends on the concentration of OA and the presence of salts in solution. We expect the information obtained from this study to be of great value in predicting the nature of complexes with a given guest and facilitating appropriate guest chosen by researchers.
通过研究多种具有不同尺寸和功能的有机分子与八酸（OA，一种合成的深腔穴状配体）的络合行为，已经阐明了决定有机分子被纳入八酸的因素。已注意到形成了两种类型的络合物：一种我们称为穴状配体络合物，它是一种部分开放的络合物，其中客体分子的一部分仍暴露于水中；另一种称为胶囊络合物，它是通过两个OA分子的组装形成的。在胶囊络合物中，客体受到水的保护。一般来说，具有离子头基的客体分子形成穴状配体络合物，而其他所有分子形成胶囊络合物。胶囊络合物在胶囊内可能包含一个或两个客体分子。小的有机分子（长度<10 Å）可能形成2:1和2:2的胶囊络合物，而较长的分子（>12 Å）优先形成2:1的胶囊络合物。已经进行了广泛的1H NMR实验来表征主客体络合物。在没有客体的情况下，OA倾向于在水中聚集。聚集程度取决于OA的浓度和溶液中盐的存在。我们期望从这项研究中获得的信息在预测与给定客体形成的络合物的性质以及帮助研究人员选择合适的客体方面具有很大的价值。
