Preparation And Application Of Aggregation-Induced Luminescent Materials Of Tetraphenylethylene

Aggregation-induced luminescence(AIE)is a photophysical phenomenon in which molecular aggregates exhibit stronger emission than single molecules,which is completely opposite to the traditional aggregation-induced quenching(ACQ)phenomenon.AIE materials have been developed for nearly 20 years,and their discovery solves the problem of low fluorescence quantum yields of traditional luminescent materials in aggregated or solid thin films.At present,AIE materials have shown great application potential in the fields of optoelectronic devices,chemical sensing,and biological imaging,and are known as"all-round athletes"in the new material arena.This thesis focuses on AIE materials,and introduces the concept of AIE into conjugated porous polymers and mechanochromic materials.A series of research work has been carried out:(1)It is of great research significance to develop porous polymer films with high emission efficiency while overcoming the limitations of difficult processing and poor optical functionality in the field of conjugated porous polymers(CPPs).AIE active tetraphenylethylene and carbazole unit monomer 1,1,2,2-tetra(9H-carbazol-9-yl)phenylethylene(CPE-4).In the mixed system of dichloromethane(CH₂Cl₂)and boron trifluoride ether(BFEE),CPP(PCPE-4)membrane is prepared by electropolymerization without adding any supporting electrolyte.Due to the TPE with AIE activity,these CPPs films exhibit high fluorescence in the solid state.Their electrochemical polymerization and fluorescence properties can be changed by adjusting the polymerization conditions.(2)Mechanically discolored materials are an important branch of stimulus-responsive materials.However,due to its low fluorescence quantum yield under solid-state conditions and unclear discoloration mechanism,it appeared late,and its development has also encountered a bottleneck.In this work,we propose a molecular conformation modification strategy to prepare mechanochromic materials with high solid-state luminous efficiency.Compounds containing tetrastyrene(TPE),carbazole and indole units(CPE-1,CPE-2,CPE-4,IPE-2 and IPE-4)were synthesized.Due to the presence of the aggregation-induced light-emitting unit TPE,these compounds all have strong solid-state emission.CPE-4 and IPE-4 show good dyschromic properties,which are better than CPE-2,CPE-1 and IPE-2.It is possible that the larger size of carbazole and indole will regulate the torsion of molecules,which in turn affects the arrangement of molecules.XRD results confirmed that the mechanical properties of color development are indeed related to changes in molecular conformation and stacking mode.Finally,CPE-4,which has excellent color-changing properties,was successfully applied to fluorescent writing.