Study On The Synthesis And Properties Of Aniline-involved Hemicucurbituril

Hemicucurbituril,a macrocyclic compound composed of methylene bridged ethyleneurea.In 2004,Miyahara and coworkers published the synthesis of macrocycles consisting of nethyleneurea units connected by n methylene bridges where n=6 and 12.It has brought new research directions to scientific researchers at home and abroad.The synthesis of new macrocyclic compounds is an eternal and challenging research content in supramolecular chemistry.At present,many modification studies have emerged based on the basic skeleton of Hemicucurbituril(ethyleneurea derivatives).Since then,a number of ethyleneurea derivatives were reacted with formaldehyde,giving rise to many other hemicucurbituril derivatives.These include also bambusurils(BU[n]),semithio-and semiaza-bambusurils(s BU[n]),and biotinurils(Bio[6]),macrocycles consisting of 2,4-substituted glycoluril and biotinuril monomeric units as special examples of substituted ethyleneureas.However,the skeleton of the modified semicircular ring was still the basic structure of methylene bridged ethyleneurea.In this paper,a new type of Hemicucurbituril macrocyclic compounds with methylene bridged ethyleneurea and aniline structure were synthesized by substituting some ethyleneurea units in semicircular ring with aniline structure.The supramolecular chemical properties of the new macrocyclic compounds with ions and organic subunits were explored.This paper mainly consists of the following parts:(1)Synthesis of aniline-involved Hemicucurbituril[6]:through the improvement of reaction conditions:3,5-bis-(bromomethyl)nitrobenzene and ethyleneurea were used to establish the corresponding fragments,and then the new hemicucurbituril derivatives was successfully synthesized by fragment method.The synthesis conditions of the fragments and macrocycles were optimized,and the products were characterized by ¹H NMR,¹C NMR,HRMS and X-ray single crystal diffraction.(2)Study on the supramolecular chemical properties of aniline-involved Hemicucurbituril[6]and ions:the supramolecular chemical properties of the new semicircular ring and some anions and metal cations were studied by UV absorption-visible spectrum and fluorescence spectrum.It was found that the new semicircular ring had certain effect on the selected anions(such as Br^-,Cl^-,I^-),trifluoromethanesulfonate(CF₃SO₂^-)and iodide(I^-)It's a good choice.Fe³⁺and Cu²⁺have the strongest quenching effect with the new semicircular ring.The binding ratio between the new semicircular ring and the new semicircular ring was investigated by job method.The detection limit between host and guest was obtained by fitting the fluorescence quenching curve,and the equilibrium constant between host and guest was calculated by fluorescence titration experiment.In order to explore the fluorescence quenching effect of metal ions on the Host,interference experiments were carried out,and it was found that other ions had no effect on the quenching effect.Therefore,the new semicircular ring has potential application as a fluorescence probe for the detection of Fe³⁺and Cu²⁺.(3)The host-guest interaction between aniline-involved Hemicucurbituril[6]and phenol small molecule:the host-guest interaction between aniline-involved Hemicucurbituril[6]and phenol small molecule was explored by fluorescence spectrum.The binding ratio,stability constant,detection limit,fluorescence quenching effect and corresponding fluorescence quenching process between macrocyclic and guest were studied by fluorescence titration experiment combined with job method.It was found that aniline semicircular ring could be used to identify nitrophenols.The binding ability of anilines with nitrophenols was(p-nitrophenol)4-NP>(2,4,6-trinitrophenol)TNP>(m-nitrophenol)2-NP>(o-nitrophenol)3-NP,which was consistent with the acidity of the selected phenols.It shows good selectivity for p-nitrophenol and potential application in phenol wastewater treatment.