Jankowski Christopher K, Lamouroux Christine, Jiménez-Estrada Manuel, Arseneau Sebastien, Wagner Brian D
Département de Chimie et Biochimie, Université de Moncton, Moncton, NB E1A 3E9, Canada.
Instituto de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, México D.F. 04510, Mexico.
Molecules. 2016 Nov 18;21(11):1568. doi: 10.3390/molecules21111568.
The molecular hosts cyclodextrins form inclusion complexes with a wide variety of guests, resulting in complexes with various host:guest stoichiometries. In the case of a series of 19 1,4-naphthoquinolines as guests with either β- or γ-cyclodextrin studied using electrospray mass spectroscopy, in most cases only 1:1 complexes were observed, with 2:1 host:guest complexes observed in just 6 out of 38 host:guest combinations. It is shown that these higher-order complexes were observed only in the case of small (or no) electronically withdrawing substituents, and were much less likely in the case of the larger γ-cyclodextrin host. The size and electronic properties of the substituents involved shows that both steric and electronic factors must be taken into account in predicting which cyclodextrin host:guest stoichiometries will be stable enough to form (or once formed, be robust enough to be observed in the ESI-MS experiments). It is clear that the prediction of host-guest stoichiometry for a specific host-guest pair is complicated, and involves a subtle interplay of both electronic and steric factors. However, there are definite trends, which can be used to help predict host:guest stoichiometry for a given host-guest pair.
分子主体环糊精能与多种客体形成包合物，从而产生具有不同主体:客体化学计量比的复合物。在使用电喷雾质谱法研究一系列19种1,4 -萘醌作为客体与β - 或γ - 环糊精形成的复合物时，在大多数情况下仅观察到1:1的复合物，在38种主体:客体组合中仅有6种观察到2:1的主体:客体复合物。结果表明，这些高阶复合物仅在具有小的（或无）吸电子取代基的情况下被观察到，并且在较大的γ - 环糊精主体的情况下出现的可能性要小得多。所涉及取代基的大小和电子性质表明，在预测哪些环糊精主体:客体化学计量比足够稳定以形成（或一旦形成，在电喷雾质谱实验中足够稳定以被观察到）时，必须同时考虑空间和电子因素。显然，预测特定主体 - 客体对的主体 - 客体化学计量比是复杂的，并且涉及电子和空间因素的微妙相互作用。然而，存在一些明确的趋势，可用于帮助预测给定主体 - 客体对的主体:客体化学计量比。
