Click Preparation And Application Investigation Of 1,2,3-triazole-bridged AIE Florecence Molecules

The design and synthesis of fluorescent molecules with multiple specific responses has always been a hot and difficult point in the field of intelligent sensing research.Compared with the fluorescence quenching(ACQ)effect of traditional fluorescent molecules,aggregation-induced emission(AIE)provides a new idea for constructing"optical switch"functional sensing molecules,and has become an important research frontier leading the development of intelligent fluorescent materials.Click chemistry is an important modular synthesis tool.Among them,the monovalent copper catalyzed 1,3-dipolar cycloaddition reaction between azide-terminal alkyne is favored for its high efficiency,rapidity and stereospecificity.In the field of sensing,click chemistry as a bridging method has been applied to construct a variety of sensing systems,and the triazole group derived by click has shown excellent properties act as an excellent synergistic recognition site in the coordination of metal and hydrogen bonds,electrostatic and?-?action,but there are few reports about the AIE fluorescence recognition molecules relying on the triazole recognition group.In this paper,a series of 1,2,3-triazole/triazolium bridged AIE fluorescent sensor molecules were designed and prepared by click chemistry with tetraphenylethylene(TPE)that is the star molecule in the AIE field as the fluorescence reporting unit.The new AIE fluorescence sensing systems have been developed by combining metal coordination,space,static electricity,hydrophilic and hydrophobic effects and low solubility product effects with the photophysical process of AIE;the fluorescent sensing technology has been innovated.The main research is as follows:(1)Synthesis of AIE aniline fluorescent molecules bridged by triazole with synergistic coordination ability and specific recognition to Cu²⁺.o-TPE-NH₂,m-TPE-NH₂,p-TPE-NH₂ with different amino substituent positions were prepared by coupling the alkynyl TPE with the ortho,meta-and para-amino substituted phenylacetylenes by a click-cycloaddition reaction.o-TPE-NH₂ has good selectivity to Cu²⁺by the synergistic coordination of triazole nitrogen with the adjacent amino group,which can induce the energy transfer through the coordination of Cu²⁺in the mixed solvent,resulting in fluorescence quenching.After combining with Cu²⁺in pure acetonitrile solution of o-TPE-NH₂,the solution system can change from colorless to pink to realize the visual detection of Cu²⁺.In addition,the fluorescence intensity of p-TPE-NH₂ is linear with p H within a certain range and can be a p H fluorescent probe.(2)Low K_sp-mediated aggregation of AIE triazolium and specific recognition to Hg²⁺/Ag⁺.The tetraphenylethylene coupled with the benzene ring by a click reaction,and the triazole ring was cationized by methyl iodide to prepare a fluorescent triazole iodide(AIETOI)with AIE characteristics.The sensing performance of the probe on the metal ion was studied.The novel probe has a highly sensitive specific lighting-up capability for mercury or silver ions at ppm levels,followed by fluorescence quenching with excess Hg²⁺or Ag⁺.Hg²⁺/Ag⁺can coordinate with the semi-dissociated iodide in the ACN/H₂O solution,causing the aggregation and fluorescence lighting-up of AIETOI,and subsequent fluorescence quenching can be attributed to the"peeling"of AIETOI molecules from aggregates.The response of AIETOI to Hg²⁺/Ag⁺is relatively inert to p H,ionic strength and other ion interference,showing high selectivity and sensitivity,which provides a new idea for the design of fluorescent probes.(3)Preparation of triazolium fluorescent sensor molecules with selective electrostatic action and specific recognition of sulfonic acid polysaccharides.On the basis of the above research,the tetraphenylethylene was conjugated with the benzene ring by click reaction followed by cationization reaction using tetrafluoroborate instead of iodide methyl iodide to synthesize the fluorescent triazolium molecules with AIE tunable properties(AIETBF).The strong electron-withdrawing ability of triazolium can induce intramolecular charge transfer(ICT),which significantly attenuates the AIE properties of TPE in solution.AIETBF can bind to the heparin skeleton through the special"?electrostatic locking"action between triazolium and sulfonic acid groups,which can balance the charge of AIETBF to recovery the AIE characteristics of TPE.The triazolium probes exhibited a highly specific turn-on fluorescence response toward such molecules by the self-assembly of amphiphilic complex in a solution environment.Additionally,the results of cryo-electron microscopy(Cryo-EM)show that this method can be an effective means to prepare"AIE dots".(4)Click synthesis and performance study of AIE polyrotaxane supramolecules.Coupling the azido-tetraphenylethylene with ethyl propiolate by click reaction,the TPE molecule with terminal group and triazole was synthesized by hydrolysis of the ester.Finally,we successfully prepared a polyrotaxane molecule with AIE properties by esterification of polyrotaxane molecule that possess multiple reactive sites and TPE molecule that have a triazole active site,the structure was characterized by IR,NMR and other means.Discovered by studying its basic spectral properties,the polymer exhibits excellent AIE characteristics;In addition,the polymer shows strong stability to environmental p H,various metal cations and amino acids,which laid a foundation for its application research.In summary,a series of fluorescent probes with AIE properties based on triazole recognition unit were proposed and prepared for the first time,which achieved high sensitivity and specific detection of ions and biomacromolecules,and it provided a new idea for the design and application of aggregation-induced emission sensors.