Complexation of alendronate sodium (AlnNa) with β-cyclodextrin (β-CD) was studied by means of ESI-mass spectrometry. The experimental results show that stable 1:1 inclusion complexes between selected bisphosphonates and β-CD were formed. In addition, complexes with different stoichiometry were observed. DFT/B3LYP calculations were performed to elucidate the different inclusion behavior between alendronate and β-CD. Molecular modeling showed that the inclusion complex of Aln-β-CD where the two phosphonate groups bound to the central carbon atom of bisphosphonate were inserted into the cavity of β-CD from its “top” side was thermodynamically more favorable than when they were inserted from its “bottom” side; the complexation energy was −74.05 versus −60.85 kcal/mol. The calculations indicated that the formation of conventional hydrogen bonds was the main factor for non-covalent β-CD:Aln complex formation and stabilization in the gas phase.

中文翻译：

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阿仑膦酸钠与β-环糊精包合物的质谱和分子模型研究


通过 ESI 质谱法研究了阿仑膦酸钠 (AlnNa) 与 β-环糊精 (β-CD) 的络合。实验结果表明，所选双膦酸盐与β-CD之间形成了稳定的1:1包合物。此外，还观察到具有不同化学计量的复合物。进行 DFT/B3LYP 计算以阐明阿仑膦酸钠和 β-CD 之间不同的包合行为。分子模型表明，Aln-β-CD 的包合物（其中与双膦酸酯中心碳原子结合的两个膦酸酯基团从其“顶”侧插入到 β-CD 的空腔中）在热力学上比插入时更有利从它的“底部”一侧；络合能为-74.05 vs -60.85 kcal/mol。计算表明，常规氢键的形成是非共价β-CD:Aln配合物在气相中形成和稳定的主要因素。