Design,Synthesis And Properties Research Of Dual-State Emitting Molecules Based On Aggregation-Induced Emission Molecules

Aggregation-Caused Quenching(ACQ)and Aggregation-Induced Emission(AIE)have attracted wide attention of researchers since it was discovered.Traditional ACQ molecules are widely used in fluorescence probe,biological imaging and other fields,but photobleaching,self quenching,small stokes shift and low signal-to-noise ratio have caused restrictions in applications.AIE molecules are widely used in the fields of biology and materials,but they also have problems such as complex modification,large background interference and short emission wavelengths.Both ACQ molecules and AIE molecules can only emit strong fluorescence in a single state,and can not provide a continuous optical signal,which has great limitations in application.In recent years,Dual-state emitting(DSE)molecules that can exhibit strong luminescence in dispersed and aggregated states,it have begun to attract widespread attention.Compared with ACQ molecules and AIE molecules,dual-state emitting molecules can provide continuous optical signal and it can enrich the research of fluorescence field.In this article,we put forward two kinds of design strategies starting from the luminescence mechanism of AIE molecular design as a new idea of constructing DSE molecule,has chosen an AIE molecules 2,3,5,6-tetraphenoxyterephthalonitrile(TPOBC)and tetraphenylethylene(TPE)as the research object,through the reasonable design and retrofit,based on an AIE by constructing DSE molecular target,and gives two kinds of universal strategy for design DSE molecular.The main research contents of this article are as follows:(1)Taking the AIE molecule TPOBC as the starting point of research,by reducing and restricting the rotor of AIE molecular,weakening intramolecular motions,through this strategy,the regulation of AIE molecules to DSE molecules is achieved,further by changing the substituent on the chromophore,realize the regulation from blue luminescence to red luminescence.Through the above design strategy,the target molecule 3,13-bis(carbamoyl)benzo-1,2,4',5'-bis(1,4-benzodioxane)(DCABBD),3,13-dicyanobenzo-1,2,4',5'-bis(1,4-benzodioxane)(DCBBD)and3,13-dialdehyde benzo-1,2,4',5'-bis(1,4-benzodioxane)(DABBD)was synthesized,the three target molecules in solution and solid state can release the strong fluorescence.We successfully realized the optically controllable adjustment from AIE molecule to DSE molecule through reasonable design.(2)Taking the AIE molecule TPE as the starting point for research.By introducing electron-donating groups and electron-accepting groups,increases the molecular polarity,making an AIE molecules optical behavior change.The target molecule 1,1,2,2-tetra(4-nitrophenyl)ethylene(TNPE),(E)-1,2-bis(1H-indol-1-yl)-1,2-bis(4-nitrophenyl)ethylene(DIBNPE)and(E)-1,2-bis(9H-carbazol-9-yl)-1,2-bis(4-nitrophenyl)ethylene(DCBNPE)was designed and synthesized.The structure of DIBNPE and DCBNPE is similar to TPE,and DCBNPE belongs to a typical DSE molecule,at the same time,by combining the experimental data and theoretical calculation,i.e.,by increasing the polarity of AIE molecules,it can realize the transformation from AIE molecules to DSE molecules.At the same time,we found that DCBNPE also has multi-stimulus response luminescence properties,and we successfully applied it to encryption and anti-counterfeiting.To sum up,we took AIE molecule as the starting point,and through reasonable design and modification,the target molecule released strong fluorescence in both solution and solid states,thus realizing the regulation of fluorescence behavior from AIE molecule to DSE molecule.In addition,the target molecule DCBNPE in the third part work also has a significant stimulatory fluorescence response behavior,and this property of DCBNPE is applied to encryption and anti-counterfeiting.This study presents a new strategy for the design of DSE molecules,which enriches the study of the regulation of fluorescence behavior.