Synthesis And Characterization Of An Efficient AIE-active Molecule Containing 1,3,4-oxadiazole Derivative Compounds

Design and synthesis of highly efficient solid-state organic materials is of fundamental importance, and has technical implications because most of the materials are applied as thin films, or in aggregate states, in optoelectronic devices. However, most of these compounds only have reasonable emission in dilute solution and their emission inaggregated states becomes much weaker or disappears, owing to the notorious effect of aggregation-caused quenching(ACQ). The aggregation-caused quenching greatly limits the application of the luminescent material. Herein, we have tried to integration of AIE and intramolecular charge transfer (ICT) into one compound has led to a new phenomenon:this type of material can emit strong fluorescence not only in the solid state or aggregation forms, but also in dilute solutions. A series of new compounds (OZA-SO1、OZA-SO2、 OZA-SO3、OZA-SO4) which contain 1,3,4-oxadiazole and sulfone were synthesized, and studied their optical properties and thermal stability.The chemical structures of result compounds OZA-SOs were determined by 1H NMR, 13C NMR, FTIR, and MS. The optical properties of OZA-SOs in THF/water mixtures were studied.The PL intensity of OZA-SOs was decreased when a "small" amount of water was added to THF, owing to the increased solvent polarity. The PL intensity of OZA-SOs was increased when a "larger"amount of water was added to THF, which confirmed the existence of AIE. The optical properties of OZA-SOs were investigated in different solvents. The absorption peak is slight changes with increasing solvent polarity. In contrast, the PL behavior of OZA-SOs varies dramatically with changes in solvent polarity, which confirmed the existence of ICT. The target compounds were soluble in the normal organic solvent such as toluene, chloroform, dichloromethane, N-methyl-2-pyrrolidinone, Dimethyl sulfoxide, and so on. Thermodynamic properties was studied by DSC and TG, thermal-decomposition temperatures are over 350℃, which indicated that these materials possess excellent thermal stability. These compounds have good chemical and thermal stability, and can emit fluorescence in the state of aggregation, which show that such compounds are expected to be a good target electroluminescent material.