The inclusion behaviour of compounds N , N′ -bis(9-cyclohexyl-9-xanthenyl)ethylenediamine (OED) and N , N′ -bis(9-cyclohexyl-9-thioxanthenyl)ethylenediamine (SED) was assessed in the presence of pyridine (PYR) and its three methylpyridine isomers (2MP, 3MP and 4MP). PYR, 3MP and 4MP were each enclathrated by OED when it was recrystallized independently from each guest solvent, but failed to include 2MP. The thio host derivative, SED, was less efficient, forming a complex only with PYR. When these guests were mixed in equimolar amounts and each host recrystallized from the mixture, OED constantly displayed a significantly enhanced preference for 4MP (near-complete in many instances), while complexation failed under these circumstances for SED, even when PYR was present in the guest mixture (despite PYR having been included in the single solvent experiment). A selectivity order of 4MP (92.8%) ≫ PYR (6.0%) > 3MP (0.9%) > 2MP (0.3%) was noted for OED when it was recrystallized from the equimolar quaternary mixed solvent system. The selectivity of OED towards 4MP was investigated using single crystal diffraction (SCXRD) and thermal (TA) analyses: interestingly, only 4MP experienced a strong classical hydrogen bond with OED, in direct relation to the enhanced selectivity of OED for 4MP while, additionally, this complex displayed an increased thermal stability relative to the other two complexes with OED.

中文翻译：

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甲基吡啶异构体存在下乙二胺衍生物对吡啶的包合能力和选择性

化合物 N, N' -双(9-环己基-9-呫吨基)乙二胺 (OED) 和 N, N' -双(9-环己基-9-硫杂蒽基)乙二胺 (SED) 的包合行为在吡啶 (PYR) 及其三种甲基吡啶异构体（2MP、3MP 和 4MP）。PYR、3MP 和 4MP 在从每种客体溶剂中独立重结晶时都被 OED 包覆，但不包括 2MP。硫代宿主衍生物 SED 效率较低，仅与 PYR 形成复合物。当这些客体以等摩尔量混合并且每个主体从混合物中重结晶时，OED 不断显示出对 4MP（在许多情况下接近完全）的显着增强的偏好，而在这些情况下，SED 的络合失败，即使当 PYR 存在于客体混合物中时（尽管 PYR 已包含在单一溶剂实验中）。当 OED 从等摩尔四元混合溶剂系统中重结晶时，OED 的选择性顺序为 4MP (92.8%) ≫ PYR (6.0%) > 3MP (0.9%) > 2MP (0.3%)。使用单晶衍射 (SCXRD) 和热 (TA) 分析研究了 OED 对 4MP 的选择性：有趣的是，只有 4MP 与 OED 经历了强的经典氢键，这与 OED 对 4MP 的选择性增强直接相关，另外，相对于其他两种具有 OED 的复合物，该复合物显示出更高的热稳定性。