Synthesis And Application Of Benzopyran Acylhydrazone Schiff Base Organic Gelator

In recent years,Low molecular mass organogels have been received more and more attention,and a large number of organogel compounds with different structures and properties have been synthesized by researchers.In addition to understanding the self-assembly behavior of organogels,it is more important to explore their potential application.So far,low molecular mass organogels have good application in drug delivery,chemical sensors,tissue engineering,biomimetic systems,optoelectronic devices and other fields.While chemical sensors based on fluorescent organogels are a very important part of the field.Schiff base mainly refers to a class of organic compounds containing amine or azomethine groups,usually formed by condensation of an amine group with an aldehyde carbonyl group or a ketone carbonyl group.Those compounds have various characteristics and can be acted as complexing reagents.The acylhydrazone schiff base compound has a-CONHN=CN-functional group,and has good fluorescence characteristics to recognize metal ions,and can be used as fluorescent probe.Benzopyrans are very common in nature,with many biological activity and extensive application.Those compounds can be used in medicine,dyes,biological,optical,and other fields.The introduction of the acylhydrazone functional group into the organogelator can improve the biological activity and coordination ability,and can also provide hydrogen bond self-assembly driving force,thereby improving the gel-forming ability.At present,there are few studies on benzopyrans with acylhydrazone schiff structure.It is very important to study organogelators with benzopyran and acylhydrazone schiff structure.Therefore,we want to develop organogelators with high characteristic.Combining the advantages of low molecular mass organogels and acylhydrazone schiff base compounds,three novel benzopyran acylhydrazone schiff base organogel compounds G₁,G₂ and G₃ were designed and synthesized.Their structures were characterized by ¹H NMR,¹³C NMR,and HRMS spectra.It has been found in organogel experiments that they can form stable organogels in ethanol,isopropanol,tert-amyl alcohol and other organic solvents.And they can response to heating,light irradiation and shaking efficiently,the solution can be reformed to the gel state after being cooled for about0.5h.The self-assembly of the organogels were investigated by infrared spectroscopy and X-ray diffraction.The results indicated the intermolecular H-bonds,Van der Waals interactions andπ-πstacking may be self-assembly for the organogel formation.It has been found in scanning electron microscopy that the organogels formed are present in entangled network structures or irregular sheet structures.The optical properties of three compounds were studied by UV-visible spectroscopy and fluorescence spectra.Those compounds can be used to determine Fe³⁺or Cu²⁺with high selectivity and sensitivity.The stoichiometric between the organogelators and metal ions was determined by Benesi-Hildebrand and found to be 1:1.