Synthesis And Sensing Properties Of Small Molecular Fluorescent Materials With Good Solid State Optical Properties

This thesis primarily expounded the luminescence characteristics and advantages of fluorescent materials with good solid-state optical properties.For such fluorescent materials,the mechanism of aggregation-induced emission was summarized,and the recent applications in the sensing fields such as anion recognition,metal cation recognition,and pH identification were summarized.In this thesis,four kinds of organic small molecule fluorescent materials with good solid-state luminescence properties were synthesized.The photophysical properties of solid and liquid were studied in detail,and their application in the sensing field was explored.（1）Coumarin amide derivatives 1-4（?）（2）Chalcone derivatives 5 and 6（?）（3）Pyrene derivatives 7-8（?）（4）Metal complex 9（?）In the coumarin amide derivative system,four coumarin amide derivatives 1-4were synthesized and characterized.The single crystal structures of compounds 1 and2 were obtained,and the photophysical properties and recognition properties of these four compounds were systematically studied.All the solid powders of compounds 1,3and 4 had bright yellow-green or yellow fluorescence under ultraviolet light,while the solid powder of compound 2 had bright blue fluorescent.Among them,compound 1has the highest solid absolute quantum yield（Φ₁:0.47）and compound 4 exhibits aggregation-induced emission properties.In THF-H₂O mixed system,the yellow fluorescence emission gradually increases with the increase of water fraction.All four compounds were developed to recognize ClO^-in aqueous solution.By titration,it was found that compound 1-3 were“turn-off”fluorescence probes and compound 4 was a“turn-on”fluorescence probe.Four compounds had good selectivity and sensitivity to ClO^-.Among them,compound 4 had the lowest fluorescence detection limit,so it had the best recognition property for ClO^-.Two chalcone derivatives 5 and 6 were designed and synthesized.Their structures were systematically characterized.Through detailed testing of photophysical properties,it is found that the fluorescence spectra have obvious red shift with the increase of solvent polarity.The solid powders of both compounds 5and 6 emitted red fluorescence under UV light,wherein the solid powder fluorescent emission of 5 was in the deep infrared region.Through titration tests,it was found that compound 5 can specifically recognize copper ions in the aqueous solution by the naked eye and the sensitivity is better,while compound 6 does not respond to copper ions.It was concluded by structural comparison and mechanism analysis that the hydroxyl group and carbonyl group of 5 had a 1:1 coordination with the copper ion.In the pyrene derivative system,compounds 7 and 8 were designed and synthesized with pyrene as the basic unit.Compound 7 obtained crystal structures of monoclinic and triclinic crystal systems in different solution environments.The liquid photophysical properties of compounds 7 and 8 in common organic solvents were investigated in detail.It was found that the two compounds exhibited significant fluorescence emission in poor solvent water,showing typical aggregation-induced emission property.The fluorescence properties of the their solid powders were tested and the absolute fluorescence quantum yields of them were obtained,up to 31.1%and46.2%,respectively.In addition,compound 8 can achieve specific detection of ClO^-in a DMSO:HEPES=1:1（v/v,pH=7.4）with high sensitivity,which is a“turn-on”fluorescence probe for ClO^-.In the metal complex system,a novel Iridium（III）complex 9 has been synthesized and characterized.After systematic photophysical testing,it was found that the solution and solid powder of complex 9 have typical phosphorescence properties.At the same time,complex 9 also has typical aggregation-induced phosphorescence emission properties in the hexane-THF and methanol-H₂O systems.It is proved by scanning electron microscopy that the aggregation morphology and the size of aggregated particles had a significant effect on the phosphorescence properties of 9.Complex 9 can also be a pH chemosensor tomonitor pH changes in PBS buffer solution because of two successive protonation processes of pyridyl and imidazole moieties in acidic condition.