摘要/Abstract

本工作以对称二环己基取代六元瓜环(CyH₂Q[6])为主体分子, 3-吡啶甲酰肼(NH)为客体分子, 利用核磁共振(¹H NMR)、等温滴定量热(ITC)、基质辅助激光解吸电离飞行时间质谱(MALDI-TOF)研究客体分子与瓜环在水溶液中形成的物质的量比为1∶1的稳定配合物; 用X-射线单晶衍射可以观察到客体分子通过离子-偶极和氢键与瓜环端口羰基氧相互作用, 以及基于瓜环外壁正电性与无机阴离子之间形成的配合物, 从而形成多维多层次超分子框架的自组装体.
关键词: 对称二环己基取代六元瓜环, 3-吡啶甲酰肼, 配合物, 超分子框架, 自组装体
Cucurbit[n]uril (Q[n]) is a relatively new supramolecular macrocyclic compound, which has a unique structure comprised of a hydrophobic cavity with intermediate potential, two carbonyl portals with negative potential, and an outer surface with positive potential. Cyclohexyl-substituted Q[n]s have also attracted a lot of attention as the first member of the Q[n] family that can be dissolved in organic solvents and water. In this paper, the interaction modes between the symmetric dicyclohexanocucurbit[6]uril (CyH₂Q[6]) as a host and nicotinic hydrazide (NH) as a guest were investigated by nuclear magnetic resonance spectroscopy (¹H NMR), isothermal titration calorimetry (ITC), matrix assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry, and single-crystal X-ray diffraction. The ¹H NMR spectrum results showed that the proton peaks shift to the downfield, indicating that NH is located at the portal of CyH₂Q[6]. ITC experiment results showed that the binding constant (K_a) of NH@CyH₂Q[6] is (1.019±0.118)×10³ L•mol^-1, the host-guest binding ratio is 0.954±0.013, and the enthalpy value is ΔH=(–48.21±0.35) kJ•mol^-1 and entropy value TΔS=(–31.04±0.52) kJ•mol^-1. The MALDI-TOF mass spectrum also showed that the molecular ion peak m/z is 1242.4542 (theoretical value: 1242.1603), which is attributed to [CyH₂Q[6]•HNH]⁺. These experimental results showed that CyH₂Q[6] formed a stable 1∶1 exclusion complex with NH in an aqueous solution. In addition, the host CyH₂Q[6], ZnCl₂ and the guest NH were added to HCl aqueous solution, and the complex single-crystal structure was obtained by evaporation and standing. The single-crystal structure of the complex showed that there are ion-dipole interactions and hydrogen bonds between the carbonyl oxygen of CyH₂Q[6] and NH, and there are ion-dipole interactions between the outer surface of CyH₂Q[6] and [ZnCl₄]^2-. These weak interactions are the driving forces of the multi-dimensional and multi-level supramolecular framework formed by the complex.
Key words: symmetric dicyclohexanocucurbit[6]uril, nicotinic hydrazide, complex, supramolecular framework, self-assembly


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