Synthesis Of A Bridged Pillar[5]arene And Construction Of A Fluorescent Supramolecular Polymer

In recent years,with the development of supramolecular chemistry,the preparation of various smart materials using supramolecular chemistry strategies has become a hot topic in materials and biomedical fields.In addition,compared with traditional polymers,the supramolecular polymers occupy an important position in stimuli-responsive smart materials due to the non-covalent bonding with dynamic reversibility and great advantages of preparation and applications.Pillar[n]arenes,as a new class of supramolecular macrocycles bearing great advantages of convenient synthesis and easy modification,were first reported in 2008 and have acted as an important role in host-guest chemistry currently.The application of pillar[n]arenes to construct supramolecular polymers not only expands the field of supramolecular polymers but also promotes the preparation of new materials.Since the aggregation-induced emission(AIE)was reported in 2001,it has exhibited unique fluorescence properties in the aggregated state,which was different from the aggregation-caused quenching(ACQ)and has been widely used in light-emitting devices,sensing and detection,and biomedical fields.With the introduction of AIE,the supramolecular polymers efficiently combined the merits of polymers and unique emission properties,providing new opportunities for the development of supramolecular polymers,and paving new ways for the development of AIE materials in supramolecular chemistry.Thus,a fluorescent supramolecular polymer was facilely constructed from a disulfide-bridged bis(pillar[5]arene)s(P5)₂ and an alkyl-bromine-modified tetraphenylethylene DBTPE through host-guest interactions.Moreover,we explored the application of the fluorescent supramolecular polymer in the detection of nitro compounds and the construction of stimuli-responsive smart materials.The main contents of this paper are as follows:1.Through the facile modification of pillar[5]arene,a disulfide-bridged bis(pillar[5]arene)s(P5)₂ was synthesized,and then adopt the supramolecular assembly to associate an alkyl-bromide-modified tetraphenylethylene DBTPE,obtaining a fluorescent supramolecular polymer by the host-guest interaction.The supramolecular polymer was endowed with strong fluorescence owing to the AIE of DBTPE.Subsequently,we investigated the construction of the supramolecular polymer after its host-guest interaction and examined the fluorescent property in its application.Furthermore,inspired by the energy transfer mechanism,the fluorescent supramolecular polymer was used to detect nitro compounds.The results showed that the fluorescent supramolecular polymer was practical for the detection of nitro compounds with sensitive detection and an excellent limit of detection.2.In view of the presence of disulfide bonds in the disulfide-bridged bis(pillar[5]arene)s(P5)₂,we investigated the stimuli-responsive characteristics of the fluorescent supramolecular polymer.Besides,two different stimulated reagents(L-glutathione GSH in the aqueous phase and DL-dithiothreitol DTT in the organic phase)were used to act on the material,and then the fluorescence and the morphology of the material before and after stimulation were analyzed carefully.The fluorescent supramolecular polymer was disrupted due to the damage of disulfide bonding in the presence of the two stimulated reagents,while the fluorescence as well as the morphology of polymer changed significantly after stimulation.And the broken disulfide bonding can also be recovered in the presence of I₂.It can be concluded that the fluorescent supramolecular polymer possessed great potential for application in the stimuli-responsive construction of materials.More importantly,through selecting the solvent,controlling the solvent ratio and the presence or absence of reducing agents,we conducted the morphology control experiments of fluorescent supramolecular polymer,which opened up new avenues for the preparation and application of multi-functional fluorescent supramolecular polymer s in diverse materials.