Synthesis And Ion Recognition Capability Of Heteracalix[2]arene[2] Pyridine Derivatives

Heteracalixarenes were the macrocyclic compounds which formed by using heteroatoms(such as nitrogen,oxygen,sulfur,phosphorus)to substitute the bridged methylene of calixarenes or heteroaromatic rings(such as pyrrole,pyridine,pyrimidine)to replace benzene ring of calixarenes.They have good chemical stability,high melting point,the infinitely modifiable structure,and their cavity size can be regulated.these unique physical and chemical properties make heteracalixarenes hold a variety of molecular or ion recognition performance.In this paper,the tetraoxacalix[2]arene[2]pyridine derivatives were designed and synthesized.The targets were confirmed by 1H NMR,13 C NMR,HRMS and IR.The binding properties of them to cations or anions were observed by fluorescence spectra and UV/vis spectrometry.The result showed that compound 6a was found to recognize Fe3+ and Cu2+;Compound 6b has a good selectivity and naked eye recognition for Fe3+;Compounds 7b and8 b have a good selectivity for Pb2+.The binding ratios and binding constants were simultaneously obtained by nonlinear fitting plot deduced by Zhengyue Ma.The Gibbs free energy change of the ion recognition reactions and the detection limit of the compounds to recognized ions were calculated.It was confirmed that the designed targets can selectively recognize some cations,so they should be further researched.And a new nonlinear fitting plot to understand the host/guests analysis was provided,by which the binding ratio and associate constant of host/guests can be obtained simultaneously.