2，7-萘二磺酸导向构筑的五元瓜环-碱金属及碱土金属基超分子自组装体及其溶剂识别

以2,7-萘二磺酸（2,7-H₂NDA）作为结构导向剂,与五元瓜环（Q[5]）和碱金属、碱土离子（K⁺、Rb⁺、Mg²⁺、Ca²⁺）在水热条件下制备出了4种新颖的Q[5]基超分子自组装体[K₂（H₂O）₄（Q[5]）]（2,7-NDA）·4H₂O （1）、[Rb₂（H₂O）₅（Q[5]）]（2,7-NDA）·3H₂O （2）、[Mg （H₂O）₄（Q[5]）]（2,7-NDA）·8H₂O （3）和[Ca （H₂O）₄（Q[5]）]（2,7-NDA）·10H₂O （4）。单晶X射线衍射测试结果表明,自组装体1和2具有相同的结构： Q[5]分子与金属离子配位形成的是“分子胶囊”;而在3中Q[5]与Mg²⁺配位形成的是1：1型简单配合物结构;在自组装体4中,Q[5]与Ca²⁺配位形成的是一维Q[5]-Ca²⁺配位聚合物链结构。这些结构中2,7-NDA^2-阴离子平衡了体系电荷,且通过其与瓜环外壁之间的弱相互作用,促进自组装体最终构筑成三维超分子结构。此外,还研究了自组装体4的溶剂识别荧光传感性能,结果表明其能够作为有机溶剂丙酮和DMF的猝灭型荧光探针。

Construction and solvent recognition of cucurbit[5]uril-alkali metal and alkali-earth metal supramolecular self-assembly induced by 2,7-naphthalene disulfonic acid

By introducing 2,7-naphthalene disulfonic acid (H₂NDA) as a structure-directed agent, four new Q[5]-based supramolecular self-assemblies, namely[K₂(H₂O)₄(Q[5])](2,7-NDA)·4H₂O (1),[Rb₂(H₂O)₅(Q[5])](2,7-NDA)· 3H₂O (2),[Mg(H₂O)₄(Q[5])](2,7-NDA)·8H₂O (3), and[Ca(H₂O)₄(Q[5])](2,7-NDA)·10H₂O (4), were prepared under hydrothermal conditions. Single crystal X-ray diffraction results show that the self-assemblies 1 and 2 have the same structure. The coordination of the Q[5] molecule with metal ions forms a "molecular capsule" structure in 1 and 2, while the coordination of Q[5] and Mg²⁺ in 3 forms a 1:1 simple complex structure. In 4, Q[5] and Ca²⁺ can directly coordinate to form a 1D Q[5]-Ca²⁺coordination polymer chain structure. The 2,7-NDA^2- anions in these structures balance the system charge, and through their outer-surface interactions with Q[5], promote its final construction into a 3D supramolecular structure. In addition, we also studied the fluorescence sensing properties of self-assembly 4, which could be used as quenching fluorescence probes for the organic solvents acetone and DMF.