Construction Of Supramolecular Assemblies And Study On Tunable Fluorescent Emission Based On Bibenzimidazole

With the rapid development of luminescent materials,organic fluorescent molecules play an increasingly important role in this field.Improving the aggregated fluorescence quench（ACQ）effect of traditional organic luminescent molecular has a crucial role.Meanwhile,due to their dynamic reversibility,supramolecular assemblies using weak intermolecular interactions makes them promising for many applications in chemical sensing,materials preparation,chemical catalysis,cell imaging,and drug release.In this paper,we choose 2,2’-dibenzimidazole derivatives as research subjects,first by changing the atomic species and introducing different functional groups,we successfully changed their luminescence properties and improve aviod the ACQ effect;secondly,we artfully combine the fluorescent molecule with pillar[5]arene,so that retains excellent luminescence properties and has electron-rich cavities to enrich its action sites;finally,the multi-dentate ligand was introduced into the 2,2’-dibenzimidazole-bridged pillar[5]arene dimer,which was further assembled to form supramolecular polymers with tunable fluorescence colors through host-guest interactions and metal coordination interactions.The main studies are as follows:1.We designed and synthesized a series of 2,2’-bibenzimidazole derivatives,and their luminescence properties were changed through minor adjustments by altering the type of atoms and introducing different functional groups.The ACQ effect was overcome by the introduction of the ester group,and the fluorescence color change was achieved by the growth of N-H substituted chains and the introduction of heavy atoms on the backbone.2.A novel 2,2’-bibenzimidazole bridged pillar[5]arene dimer（H2）was designed and synthesized,and the 2,2’-bibenzimidazole moiety with excellent luminescence properties was combined with pillar[5]arene with the electron-rich cavity,which was found to have obvious AIE properties.Using the host-guest properties,the monopodal and bipodal guest molecules（G1/G2）were introduced respectively.After exploration,it was found that H2 can be assembled with the biped guest molecule G2,thereby constructing a supramolecular polymer H2-G2 with supramolecular aggregation-induced luminescence enhancement effect（SAIEE）.At the same time,adding Fe³⁺could destroy its polymer structure and quench its fluorescence.Taking advantage of this feature,a smart phone Fe³⁺detection device was constructed,which has the advantages of low cost,portability,and easy operation.3.We designed and synthesized three guests,studying their optical properties by UV-Vis spectroscopy and fluorescence spectroscopy,and their electronic structures were analyzed by DFT.And we selected terpyridine derivatives as the guest and 2,2’-bibenzimidazole bridged pillar[5]arene dimer（H2）as the host,a supramolecular polymerization with tunable fluorescent colors was constructed through host-guest interaction and metal coordination thing.