Construction Of Benzimidazole-based Supramolecular Assemblies And Their Applications In Chemical Sensing Material And Luminescent Materials

Supramolecular assemblies have been extensively studied because of their fundamental insights into intermolecular interactions and their potential applications to chemical sensing materials and luminescent materials.Due to its unique luminescence and coordination properties,imidazole rings have become the focus of supramolecular chemistry and material chemistry to construct supramolecular assembly through self-assembly or co-assembly of molecules.The study of imidazole ring derivatives is carried out in five parts.（1）To study the fluorescence properties of the same series of conjugated imidazole derivatives,we designed and synthesized three conjugated bisbenzimidazole derivatives B₁,B₂and B₃.The relationship between the increase of phenyl conjugated system and ion detection/adsorption was investigated.It also indicates that by adjusting the conjugation degree of benzimidazole ring B₁,B₂and B₃,the purpose of regulating selective ion recognition and efficient adsorption/removal can be achieved.（2）To improve the assembling performance and hydrophilic properties of benzimidazole,an amphiphilic carboxyl functionalized benzimidazole derivative WCB was synthesized by introducing a flexible long alkyl chain into the imidazole group.To further improve the fluorescence intensity and gel stability of supramolecular self-assembled hydrogel WCB-G,the supramolecular host and guest hydrogel WCB-α-CD was prepared by the assembly of gel factor WCB andα-CD.The supramolecular metal hydrogel WCB+α-CD@Ms with higher elasticity and stability was constructed by the coordination of metal ions Eu³⁺,Th⁴⁺,Ce³⁺,Tb³⁺and La³⁺.（3）To expand the application of supramolecular metal hydrogel WCB+α-CD@Ms,we have developed a series of supramolecular metal xerogel films as tunable multicolor photoluminescent materials.The xerogel films were obtained after drying the supramolecular metal hydrogel,while fluorescence emission was changed from blue to multicolor luminescence under ultraviolet light（λ=254～280nm）with spherical supramolecular nanoparticles morphology.Through experiments such as scanning electron microscopy,the reason why the dry gel film changed from opaque to transparent（T>90%）was explained.（4）We designed and synthesized a tripod benzimidazole derivative BZ,retaining the long alkyl chain and hydrogen bonding sites,and a supramolecular organogel BZ-G with yellow fluorescence emission was constructed successfully.Therefore,a fluorescence quenching supramolecular fluorescence sensor based on nitrophenol explosives was prepared,which could detect picric acid with high sensitivity and recognize picric acid with naked eye.In summary,three kinds of benzimidazole supramolecular assemblies were constructed successfully based on the supramolecular weak interactions.The application of chemical sensing materials and luminescent materials was studied by fluorescence detection of ions/molecules utilizing the recognition sites of supramolecular assembly,and the change of luminescent color during the coordination interaction between supramolecular assembly and metal ions.