Preparation And Properties Of Pillar[5]arene-based Supramolecular Fluorescent Materials

Supramolecular chemistry is a subject that studies the weak interaction between molecules and molecules or between molecules and ions.The study of these weak interaction has been favored by the researchers.Macrocyclic compounds,as an important representative of supramolecular chemistry,play a very important role in promoting the study of supramolecular chemistry.The discovery of each macrocyclic compound will bring revolutionary development to supramolecular chemistry.Pillar[n]arenes are a new generation of macrocyclic compounds since they were found by Ogoshi in 2008,they had been becoming a hot field of supramolecular chemistry since then.Pillar[n]arenes are the fifth generation of supramolecular hosts after crown ethers,cyclodextrins,calixarenes,and cucurbiturils,which are linked by methylene bridges at para-positions of 2,5-dialkoxybenzene rings.Pillar[n]arenes have attracted a lot of attention and have widely studied from scientists because of their unique structural advantages,such as symmetrical rigid architecture,electron-rich cavities and facile functional modification.Pillar[n]arenes show a variety of host-guest complexation properties and fluorescence properties because of its unique rich electron cavities and multiple benzene ring repeat units.This paper focuses on the study of the recognition and stimulus response properties of pillar[n]arene-based fluorescent materials.This thesis is divided into four parts:In the first part,we summarized recent studies of pillar[n]arene-based fluorescent materials.This section covers the most recent contributions from the pillar[n]arene-based fluorescent sensor field in terms of ion sensing,small molecule recognition,biomolecule detection.Meanwhile,we highlighted the stimuli-responsiveness of pillar[n]arene-based fluorescent supramolecular polymers.In addition,we also presented the research progress on the biomedical imaging of pillar[n]arene-based fluorescent materials and its future prospects.In the second part,we design and synthesize a novel functionalized bispillar[5]arene(TP5).The bis-acylhydrazone groups of TP5 provide a good binding site for ion recognition and response.Furthermore,a novel two-component supramolecular organic gel(TP5�G)was constructed by bispillar[5]arene-basedmultiple interaction.Moreover,the obtained supramolecular organic gel exhibited thermoreversible gel�sol transformation,whereas,adding the competitive ligand adiponitrile resulted in the irreversible transformation.More importantly,this two-component supramolecular gel can highly selectively and sensitively(1.56�10-7M)detect Fe3+cations.Simultaneously,a thin film based on the supramolecular gel was prepared,which was confirmed to be a convenient test kit for detecting iron ions.It is worth mentioning that the two-component supramolecular organic gel is a multiple stimulating response gel,which greatly promotes the application prospect of pillar[n]arenes.In the third part,we synthesized a novel functionalized pillar[5]arene(GP5)by multi-step reaction.Since the sides of the ring each having a hydrazide group containing a thioether bond,it can effectively form a supramolecular metal-organic polymer(GP5�Zn)via the incorporation of Zn-ligand coordination.Furthermore,the obtained linear supramolecular metal-organic polymer could self-assemble to form a fluorescent supramolecular metal-organic gel at high concentration,which exhibits multiple stimulus responses.When TBAOH was added to the viscous solution at high temperature,the obtained solution could not form a supramolecular metal-organic gel on cooling.Moreover,this metal-organic gel could effectively sense and remove Hg2+.Simultaneously,a thin film based on the metal-organic gel was prepared,which was confirmed to be a convenient test kit for detecting Hg2+.In the fourth part,we designed and synthesized a pillar[5]arene-based gelator(BTAP5).The gelator(BTAP5)could self-assemble to form a fluorescent supramolecular hydrogel(HG)at high concentration by hydrogen bonds and the ?�?stacking interactions.Meanwhile,this supramolecular hydrogel also exhibited good thermal-responsiveness,p H-responsiveness,anion-responsiveness and competitive agent-responsiveness.It is noteworthy that this supramolecular hydrogel is also an excellent self-healing and conductive material.More interestingly,this hydrogel could effectively work to fluorescent detection of iron ions(Fe3+)with high selectivity and ultra-sensitivity.Furthermore,the thin film based on this hydrogel was also prepared,which was confirmed to be a convenient test kit for detecting Fe3+.This has good application prospects in the detection of Fe3+.