Assembly And Property Study Of Cucurbitacin Ring And Monopyridine Guest Molecules Containing Conjugated Structur

In recent years,with the development of supramolecular chemistry of cucurbit[n]uril(Q[n]s),the preparation of various smart functional materials by using host-guest assembly of Q[n]s through non-covalent interactions has become a hot research topic.For example,the host-guest complex formed by the alkyl-bridged bipyridium guest with folding conformation in the Q[n]cavity has been used in the preparation of tunable fluorescent materials,room temperature phosphorescent materials,polymerization and anti-counterfeiting.Against this research background,three series of monopyridium fluorescent guest were designed and synthesized in this thesis.Their host-guest assembly properties with Q[n]s were studied.The main work was as follows:1.Three monopyridium guests bridged by different alkyl groups were synthesized through Suzuki cross coupling reaction and alkylation reaction with1-bromo-4-methoxy benzene and 4-pyridine boric acid as the main raw materials.The host-guest interactions of Q[7]/Q[8]with four guests were investigated by ~1H NMR,UV-vis and fluorescence spectra,isothermal titration calorimetry(ITC)and single crystal diffraction.Studies have shown that when Q[7]was added to the guest solution,two simple host-guest assemblies of Q[7]with the guests were formed in neutral aqueous solution(Q[7]/guest,1:1 and 2:1).Three self-assembly modes(Q[8]/guest,1:2、1:1、2:2)were formed between the Q[8]host and the guests.It should be noted that the host-guest assembly of 1:1(J type,polymer)and 2:2(H type,dimer)was observed co-existed,which confirmed by the X-ray structure.Fluorescence spectra showed that the fluorescence emission of the above-mentioned assemblers was significantly enhanced due to the macrocycle-complex restricted intramolecular motions.2.Three monopyridium guests bridged by different alkyl and its monomer were synthesized through the Heck coupling reaction and alkylation reaction with1-bromine-4-methoxy benzene,4-vinyl pyridine as the main raw material.The host-guest interaction of Q[8]with four guest moleculars were investigated by using the method of ~1H NMR,UV-vis and fluorescence spectra,ITC,single crystal diffraction.Interestingly,experiment resuts indicated that a 2:2 self-assembly mode(Q[8]/guest)was formed in all the host-guest assembly of Q[8]with the guests in this section.Fluorescence emission spectra suggested all the emission of the host-guest assembly underwent red shift,which can be attributed to the novel 2:2 assembly of the guest induced by the Q[8]host.3.The guest with dicyanovinyl group was synthesized through the Heck coupling reaction and alkylation reaction with 4-bromobenzene formaldehyde as the main raw material.~1H NMR,UV-vis and fluorescence spectra,ITC,single crystal diffraction were performed for the host-guest assembly in neutral aqueous solution.The dicyanovinyl-attached cationic guest can be used as the fluorescent response moiety for the detection of the cyanide anion in water via a nucleophilic addition reaction in the assist of the Q[8]-based 2:2 quaternary complexes.Then,the reaction of cyanide further switched the Q[8]-based host-guest assemblies from the 2:2complexes to the 1:1 supramolecular polymers that precipitate in water.Thus,the macrocyclic-based dynamic host-guest assembly has potential use in applications for solving the problem of toxic anion pollutants present in aqueous environments.