Preparation Of Pillar[5]arenes-based AIE Supramolecular Assemblies And Its Applications In Detection Of Ions

With the increasing issues of ecoenvironment degradation and health problem,ultrasensitive detection of toxic ions and molecules have become extremely important.Chemical fluorescence sensors with advantage of rapid response,high sensitivity,easy visualization and facile operation are emerging as powerful detection tools.However,the conventional fluorophores have a typical aggregation-induced quenching effect(ACQ),which greatly limits its application in fluorescent sensors.Aggregation-induced emission(AIE)materials that appeared in 2001,have strong fluorescence emission in the aggregated state,which not only conquers ACQ drawbacks,but also provide new platform for the development of fluorescence sensors with advantages of strong photostability,high signal-to-noise ratio and large Stokes'shift.Meanwhile,the dynamic reversibility of the supramolecular interactions endows pillar[n]arene-based supramolecular assemblies with efficient stimulus-response performance.Construct pillar[n]arene-based supramolecular AIE assembly materials by combining non-covalent interactions with AIE property will provide new opportunities for ultrasensitive detection and efficient removal of ions.In this dissertation,we rationally designed and successfully constructed two pillar[5]arene-based supramolecular assemblies with AIE attribute according to the prior report and the works of our research group,and explored their assembly mechanism by various characterization methods.In addition,the fluorescence detection and separation performance of these AIE assemblies as fluorescent sensors for a variety of harmful ions were investigated.The main research contents of this paper are as follows:1.We synthesized a cationic pillar[5]arene CWP5 without any traditional AIEgen,which showed a strong aggregation-induced emission in aggregate state through supramolecular assembly,so CWP5 can be regarded as a novel AIEgen.At the same time,CWP5 can be used as a fluorescence sensor to successively detect Fe3+ and F-/H2PO4-with high selectivity and sensitivity.Additionally,a portable rewritable test kit made from CWP5 provides a possibility to on-site detect the above motioned three ions and manufacture of encryption/decryption materials.2.Herein,a pillar[5]arene-based are supramolecular gel MTP5(?)HB with AIE attribute was firstly assembled using the host-guest interactions between pillar[5]arene MTP5 and guest molecular HB.Then,a signal amplification strategy was successfully introduced by rationally selecting and adding Fe3+ ions into supramolecular gel MTP5(?)HB.Accordingly,the in-suit generated non-fluorescent metal coordinated supramolecular gel(MTP5(?)HB-Fe)could serve as a fluorescence "Turn-on" sensor to detect H2PO4-selectively and ultrasensitively,and the limit of detection(LOD)of MTP5(?)HB-Fe for H2PO4-was calculated to be 2.82 nM.Therefore,the introduction of Fe3+ not only caused fluorescence quenching of MTP5(?)HB,but also provided a possibility for the ultrasensitive fluorescence detection via signal amplification.3.A pillar[5]arene-based supramolecular gel MTP5(?)HB was successfully constructed using a thioacetylhydrazine copillar[5]arene MTP5 and bisbenzimidazole derivative HB.It forms a stable supramolecular gel with a remarkable bluish white emission in DMSO:H2O=13:7 solution.MTP5(?)HB can ultrasensitively detect Cu2+and CN-,and the limits of detection are 1.55 and 1.13 nM,respectively.More importantly,the in-situ generated metallogel MTP5(?)HB-Cu after adding Cu2+can effectively removal CN-from aqueous solution with a separation rate of 94.40%.These results indicated that pillar[5]arene can be used to construct new AIE systems through the host-gust interaction and assembly interaction,thereby improving the detection and removal performance towards ions.In this dissertation,two pillar[5]arene-based supramolecular assemblies with AIE characteristic were fabricated through the non-covalent interactions,and their sequential detection performance towards anions/cations was explored by means of coordination interaction between supramolecular assemblies and cations/anions under competition mechanism.These results not only expand the scope of AIEgens,but also provides opportunity for the ultrasensitive detection and effective separation of toxic ions and molecules in supramolecular assemblies.