The Host-Guest Research Based On Crown Ether Derivatives And Multi-pyridinium Salts

Crown ethers and cryptands, have been widely used as the building blocks to construct different functional assemblies with complementary guest salts. Pseudorotaxanes, serving as the basic mechanical interlock structure, have attracted plenty of attention due to their novel topological structures and properties, and more importantly showed many potential applications as dynamic supramolecular materials. So it is of particular important to design and synthesize new pseudorotaxanes structures.This thesis, comprising two parts, mainly focused on the host-guset interaction research between crown ethers and their complementary guest molecules. In the first part, dibenzo-24-crown-8, dibenzo-24-crown-8-based cryptand, paraquat derivative and 1,2 (4-pyridinium)-ethylene derivative were designed and synthesized. In the second part, the difference of binding affinity and binding selectivity between crown ether, cryptand and their complementary guest moieties was investigated by 1H NMR, UV-Vis, ESI-MS and X-ray packing structure. In acetonitrile, dibenzo-24-crown-8-based cryptand could form host-guest complexes with two electron-deficient aromatic guest molecules (paraquat derivatives and 1,2 (4-pyridinium)-ethylene derivatives). The main driving forces to construct these pseudorotaxanes include hydrogen bond,Ï€-Ï€stacking and charge transfer interaction. Moreover, compared with dibenzo-24-crown-8, dibenzo-24-crown-8-based cryptand could form a 1:1 threaded structure with 1,2 (4-pyridinium)-ethylene derivative with high association constant in acetonitrile solution due to more suitable cave size and more binding sites. In addition, we also found that dibenzo-24-crown-8 and dibenzo-24-crown-8-based cryptand could form host-guest complexes with paraquat derivatives.