Construction Of Supramolecular Gel With Aggregation-induced White Fluorescence And Study Of Their Properties

Fluorescent materials with aggregation-induced emission effect have become a research hotspot in the field of fluorescent materials due to their unique luminescence characteristics and excellent photophysical properties in the solid phase.Supramolecular polymers combine the advantages of traditional polymers and supramolecular chemistry.Compared with polymers constructed by only one non-covalent interaction（such as hydrogen bonding,host-guest interaction,metal-ligand interaction,orπ-πstacking interaction）,the functional of supramolecular gel self-assembled through multiple non-covalent interactions has greater advantages than the traditional polymer gel.In addition,supramolecular gels have been proved to be an ideal platform for constructing aggregation-induced emission（AIE）functional materials.Supramolecular gels with AIE effect have good stimuli-responsive ability,self-healing ability and processability.It plays an important role in the field of chemical sensing and environmental monitoring.Designing and synthesizing intelligent supramolecular gel materials with unique photophysical properties for the detection of toxic ions has become one of the most important topics in recent years.On the basis of summarizing the literature and combining with the latest research progress of our group.In this paper,a series of supramolecular gels with white aggregation-induced emission were designed and constructed,and properties for ultrasensitive detection and high-efficiency removal of metal ions in water were investigated carefully.This thesis is divided into four parts,contents are as follows:In the first part,we summarized the research progress and development prospects of supramolecular gels with AIE effect in recent years.And focuses on the application of AIE characteristics in supramolecular gels,supramolecular gels based on small molecules and macrocyclic compound pillararenes and the application of supramolecular gels in the field of ion and molecular detection.Based on the research progress at home and abroad and the work foundation of this research group,and put forward my own research subject.In the second part,we designed and synthesized a p-hydroxybenzonic acid functionalized pillar[5]arene（SPA）and tri-（pyridine-4-yl）-functionalized trimesic amide（DTB）.Supramolecular polymer hydrogel（PDG）was successfully prepared with SPA and DTB in the mixed solution of DMSO-H₂O（1:1）by a simple host-guest assemble process.The most attractive point of PDG is its practical white light emitting property and can be used as a sensor array.PDG can ultrasensitive detected and efficiently separated of Pb²⁺,Cr³⁺and Fe³⁺in aqueous solution,with a removal rate that can reach up to 96%.By rationally introducing these metal ions into the PDG,a series of metal-ion-coordinated supramolecular metallogels PDG-Cr and PDG-Fe were constructed,and these metallogels can selectively detect CN^-and H₂PO₄^-,respectively.The lowest limit of detection（LOD）reached up to 10^-8mol/L.In addition,the fluorescent smart thin films are prepared based on the transient response and continuous detection of PDG to metal ions of anion and cation,which can act as a smart fluorescent display material and test kit.Inthethirdpart,wedesignedandsynthesized1-naphthylacethydrazine-functionalized tripod hydrazide（NTS）and4-aminopyridine-functionalized tripod benzamide（DTB）.NTS and DTB can form supramolecular hydrogel NDG with a critical gelling concentration of 3%in the mixed system of DMSO-H₂O（1:2,v/v）.The NDG constructed by hydrogen AIE interaction and the NDG exhibits strong white aggregation-induced emission,which provides a new platform for its application in sensing.NDG can ultrasensitive detected and efficiently separated of Fe³⁺in aqueous solution,the adsorption rate reached up to 99%.In addition,metal-ion-coordinated supramolecular metallogel NDG-Fe was constructed,which can detect F^-with a single continuous fluorescence.In addition,the prepared NDG-based thin films can be used as rewritable fluorescent display material for the continuity detection of Fe³⁺and F^-.Due to the outstanding optical behavior of the NDG,it also be used as an“IMPLICATION”logic gate at the molecular level.Based on NDG can continuity detection of Fe³⁺and F^-,"OFF-ON-OFF"fluorescent switches can was prepared.The AIE hydrogel-guided enriches the self-assembly strategy of new supramolecular polymers,which also makes it become a good candidate for flexible optical materials.In the fourth part:most of the reported ultra-sensitive detection of Cu²⁺and Hg²⁺based on rhodamine B sensing materials are carried out in solution,which greatly limits the wide application of the sensing materials.We designed and synthesized rhodamine B-based geltor BT by rationally introducing long alkyl chains.The BT can further self-assemble into a stable supramolecular organogel BTG and exhibits strong pink-white AIE.Interestingly,the BTG exhibits selective and ultrasensitive sensing property for Cu²⁺.By adding Cu²⁺into the BTG,a no fluorescence Cu²⁺coordinated metallogel BTG-Cu formed.Due to the competitive coordination of Hg²⁺,the BTG-Cu exhibits promising sensing properties for Hg²⁺,such as high selectivity and ultrasensitive,fluorescence turn-on response,instant response to Hg²⁺（<2s）,and the limit of lowest detection（LOD=0.567 n M）.In addition,the xerogel of BTG and BTG-Cu were able to remove Cu²⁺and Hg²⁺from diluted aqueous solution at an adsorption rate of 99.02%and 99.46%,respectively.The thin films based on BTG and BTG-Cu were prepared,which not only can act as supramolecular fluorescent material but a simple and efficient tool for detect Cu²⁺and Hg²⁺,respectively.The supramolecular organogel based-rhodamine has a good practical application prospect for detecting different metal ions.