Thiochromenones Derivatives:Synthesis And Aggregation-induced Emission Propertity

Organic light-emitting materials have attracted great attention because of their potential applications in light-emitting diodes and fluorescent sensors,etc.However,the traditional organic fluorescent materials generally have a large planar structure,and there is a strong ?-? interaction between molecules,which emits strong fluorescence in dilute solution,while in the aggregation state or solid phase,fluorescence quenching occurs.Therefore,the nature of light quenching(ACQ)caused by the aggregation of traditional fluorescent materials greatly limits the development of organic luminescent materials in practical applications.In contrast to the ACQ phenomenon,the aggregation induced luminescence(AIE)is weak or non luminescent in dilute solution and strong fluorescence in the aggregation phase.The discovery of AIE phenomenon fundamentally overcomes the problem of light quenching of traditional fluorescent materials.In recent years,the fluorescent AIE compounds represented by tetrastyrene and thiol derivatives have been widely reported,and new AIE systems emerge in an endless stream.Further research in the field of AIE,enriching the structure system of AIE and expanding the development of AIE will become an important measure to promote the development of organic light-emitting materials.In this paper,a series of fluorescent compounds with AIE characteristics were constructed with benzothiochromone as the molecular framework,alkyl chain and different chromophores as substituents of thiochromone 2,3 positions,such as triphenylamine(TPA),tetrastyrene(TPE),carbazole and phenoxazine,and their photophysical properties,AIE properties and crystal structure were studied.Triphenylamine and long alkyl substituted thiochromone derivatives TTPA-C6 and TTPA-C8 were obtained by iridium catalyzed cycloaddition reaction.The photophysical properties of TTPA-C6 and TTPA-C8 show that their maximum absorption peaks are basically the same,while the emission wavelength of TTPA-C8 modified by longer alkyl chain changes relatively red,which is caused by the increased intermolecular force and enhanced ICT process.The two compounds have push-pull(D-A)configuration and solvent effect.The red shift of ttpa-c8 increases with the increase of solution polarity.Both ttpa-c8 and ttpa-c6 show AIE characteristics.The change of luminescence caused by the increase of water content in the mixed solvent is due to the interaction of ICT process and aggregation induced luminescence effect.In view of the luminescent properties of thiochromone derivatives modified by TPA,compounds based on TPE,carbazole,phenoxazine and other groups were synthesized by cycloaddition reaction,and the effect of substituent groups on the luminescent properties of thiochromone derivatives was explored.Through the study of photophysical properties and aggregation induced luminescence,the five synthesized compounds have typical AIE characteristics,among which the compounds containing carbazole units show the same change process as those modified by TPA,which is also caused by the synergistic effect of ICT process and aggregation induced luminescence effect.The compounds containing phenoxazine units exhibit excellent AIE properties,and their crystal structure has been further studied.The compound has a highly twisted configuration,and there is no strong ?-? interaction between the molecules,and the head-to-head antiparallel stacking mode between the molecules is conducive to the formation of J-aggregates and enhanced fluorescence emission.