The Research On New Metal-free Cucurbit[n]uril Supramolecular Frameworks

Supramolecular chemistry is a discipline studying the association of more than two chemical species into supramolecular system with specific structure and function through non-covalent interactions. At present, supramolecular chemistry mainly focuses on the research of supramolecular hosts including crown ether, cyclodextrin, calixarene and cucurbit[n]uril (CB[n]). CB has recently become hot research area of supramolecular chemistry due to its unique hydrophobic cavity and rigid structure, especially the research on synthesis and self-assembly of CB. Room temperature ionic liquids are molten salts which are composed of specific organic cations and anions, and remain liquid state at room temperature or near room temperature, hence become well known as green solvent with non-volatility and high thermo-stability. The synthesis and applications of SO3H-functionalized ionic liquids (SFILs) have developed rapidly in recent years amongst room temperature acidic ionic liquid. CB[n] dissolves well in SFILs aqueous solution, which enables the self-assembly of CB[n] and SFILs guest molecules in water. In this thesis, the self-assembly of CB[n] with a variety of SFILs under different conditions have been investigated, as well as the self-assembly of CB[n] with organic sulfonic acids.The results show that the cationic structures of ionic liquids ([C3SO3Hmim],[C3SO3HPy],[C3SO3Htma],[C4SO3Hmim]), the anionic structures of ionic liquids (HSO4-, Br", NO3-, H2PO4-, etc.), and the size of CB[n](n=5,6,7,8) play vital roles in the assembly, while the synthetic conditions have negligible influences on the assembly. Meanwhile, the assemblies of CB[n] with organic sulfonic acids are affected by the structures of sulfonic acids and the size of CB[n].Through the screening and optimizations, totally nine novel metal-free CB[n] frameworks have been obtained, including eight crystals via SFILs and one crystal from organic sulfonic acid. As shown by the X-ray single crystal analyses, these crystals have different channel structures and solvent-accessible volumes, which have great potentials as absorption and storage materials.