Insight into the molecular interactions of homotactic and heterotactic association of caffeine and pyridine in aqueous solution is given on the basis of both experimental and simulation studies. Caffeine is about 5 times more soluble in a 3 m aqueous pyridine solution than it is in pure water (an increase from ∼0.1 m to 0.5 m). At this elevated concentration the system becomes suitable for neutron scattering study. Caffeine–pyridine interactions were studied by neutron scattering and molecular dynamics simulations, allowing a detailed characterization of the spatial and orientational structure of the solution. It was found that while pyridine–caffeine interactions are not as strong as caffeine–caffeine interactions, the pyridine–caffeine interactions still significantly disrupted caffeine–caffeine stacking. The alteration of the caffeine–caffeine stacking, occasioned by the presence of pyridine molecules in solution and the consequent formation of heterotactic interactions, leads to the experimentally detected increase in caffeine solubility.

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咖啡因和吡啶混合溶液的分子动力学和中子散射研究

在实验和模拟研究的基础上，深入研究了咖啡因和吡啶在水溶液中的同规和杂规缔合的分子相互作用。咖啡因在3 m吡啶水溶液中的溶解度约为其在纯水中的溶解度的5倍（从约0.1 m增加至0.5 m）。在这种升高的浓度下，该系统变得适用于中子散射研究。通过中子散射和分子动力学模拟研究了咖啡因-吡啶的相互作用，从而可以详细表征溶液的空间和取向结构。研究发现，虽然吡啶-咖啡因的相互作用不如咖啡因-咖啡因的相互作用强，但吡啶-咖啡因的相互作用仍显着破坏了咖啡因-咖啡因的堆积。咖啡因-咖啡因堆积的改变（由于溶液中存在吡啶分子以及随后形成的异规相互作用而引起）导致了咖啡因溶解度的实验检测增加。