Studies On Molecular Recognition And Protective Effect Of Pagoda[n] Arenes

As the main research direction of supramolecular chemistry,host and guest recognition of macrocyclic compounds has shown unique advantages in many facets,which has attracted wide attention from chemists.In recent years,the development of supramolecular chemistry has been promoted by the synthesis of macrocyclic pagoda[n]arenes.First,pagoda[n]arenes（P5,P4,i P4）were synthesized,and then the spectroscopic properties of pagoda[n]arenes were investigated to study the photophysical properties of pagoda[n]arenes under the influence of different solvents,light,temperature,concentration,and organic acids and bases.It was found that the fluorescence intensity of pagoda[n]arenes was different in different solvents,and aggregation-induced emission quenching was observed.In addition,light can cause fluorescence quenching of pagoda[n]arenes,and organic acids and bases can also affect the spectral properties,but temperature has no effect on the ultraviolet absorption and fluorescence emission of pagoda[n]arenes.Subsequently,the complexation behavior of pagoda[n]arenes（n=4,5）with ferrocene（Fc）,ferrocenium（Fc⁺）,cobaltocenium（Cob⁺）,and a derivative（TMAFc⁺）was studied.The 1:1 host-guest complexes of P4@Fc⁺and P5@Fc⁺showed strong binding affinities of 10³～10⁴ M^-1.In addition,the inclusion complex formed by the pagoda[n]arenes and Fc⁺can prevent the destruction of Fc⁺by oxygen in the organic solvent,and improve the stability and oxygen resistance of the Fc⁺,indicating the protective effect of pagoda[n]arenes.Cyclic voltammetry shows that the inclusion complexes formed by Fc⁺with P4 and Fc⁺with P5 had good oxidation-reduction responses,which makes the system of Fc⁺/Fc of pagoda[n]arenes have potential application ability in the construction of redox host-guest reaction system.Lastly,the complexation of cationic organic ammonium and phosphonium salts with pagoda[n]arenes was investigated,the identification ability of pagoda[n]arenes was determined by NMR.The complexation constant was determined by competitive fluorescence titration method to reach 10³～10⁴.This kind of research broadens the scope of guest recognition for pagoda[n]arenes and the calculation method of complex constant.Lays a foundation for its application in the field of supramolecular recognition.The photophysical properties and host and guest complexation properties of pagoda[n]arenes were studied,which broadened the field of supramolecular chemistry host and guest recognition and promoted the development of pagoda[n]arenes research.