Study On The Recognition Property Of Cucurbit[n]uril Towards Bismidazolium Salts

Supramolecular chemistry is one of the research hotspots in the current chemical field.The development of supramolecular chemistry is closely related to macrocyclic chemistry.Cucurbit[n]uril（CB[n]）,is a cyclic cage-like molecule formed by bridging multiple glycoluryl units with methylene,and it is currently one of the hottest molecules in macrocyclic chemistry.Molecular recognition is the basis for subsequent application of supramolecular chemistry.This thesis focuses on the molecular recognition of CB[n]and guest molecules.In this thesis,the recognition properties and the inclusion models of CB[n]and two bisimidazolium salts were studied by means of nuclear magnetic resonance（NMR）,ultraviolet-visible absorption spectroscopy（UV/Vis）,fluorescence emission spectroscopy（FL）,and mass spectrometry（MS）.Based on this,the application of inclusion complexes was developed and one of the complexes could be used as a metal ions fluorescent probe.The first chapter of this thesis mainly made a brief introduction to the development history and recognition properties of CB[n].And the development of CB[n]in drug delivery,fluorescence probes and supramolecular polymers was reviewed.In the second chapter of the thesis,the synthesis of two bisimidazolium salts was introduced.The inclusion models of CB[8]and these two bisimidazolium salts were studied by means of NMR,UV/Vis and FL.The results of the study showed that there are1:2（C1:CB[8]）and 1:1 inclusion models between CB[8]and C1,and the 1:2 type inclusion complex gradually transformed to 1:1 inclusion complex.CB[8]encapsulate C2forms 1:3（C2:CB[8]）complex.In the third chapter,the sensitization responses of C1,C2 and their inclusion complexes with CB[8]towards metal ions were studied by fluorescence emission spectroscopy.Since the metal ions can coordinate with the portal of CB[8],the C2@CB[8]complex has a fluorescence responsive to metal ions.We measured the binding constants of CB[8]with several metal ions.Among them,the binding constant of Fe³⁺with CB[8]is larger than Na⁺/K⁺/Ca²⁺/Mg²⁺/Mn²⁺/Cd²⁺/Cu²⁺with CB[8],reaching 10⁸ M^-2 orders of magnitude.The fourth chapter of this thesis summarizes the subject and forecasts the development of this field.