Design And Synthesis Of New Room Temperature Phosphors Based On Phenylcarbazole And Their Isomers And Polymorphic Effects

Pure organic room temperature phosphorescence?PORTP?materials have the advantages of low cost,structural flexibility,good stability and processability,etc.,so they are widely used in biological imaging,chemical sensing,data encryption and anti-counterfeiting,optical storage and other fields.However,due to the weak spin-orbit coupling of the spin orbits of pure organic molecules,PORTP materials that can be excited by visible light or highly efficient and long-lived are still limited.In this article,we designed and synthesized some cyano?-CN?phenyl carbazole and amido?-CONH2?phenyl carbazole isomers and their polymorphic systems that can be excited by visible light?420-460 nm?.The organic phosphor with ultralong RTP lifetime of 1020 ms and high RTP efficiency of 5.4%has been achieved and the application of ethyl acetate detection and oxygen sensing has been explored.First,by bonding polar groups at different positions to construct isomers and utilizing polymorphic effects,the molecular packing mode and the aggregation state structure of intermolecular interactions are the keys to determine the phosphorescence properties of PORTP materials.For the first time,it is proposed that constructing a molecular skeleton containing large-sized pores is an effective method to realize PORTP materials with chemical sensing and detection properties.In addition,for the properties of visible light excited conjugated small molecule phosphorescence,we propose that the transition-forbidden S₀?T_n process exists,and the strong spin-orbit coupling between S₀ and T_n is a necessary condition for this process.When excited by ultraviolet light and NUV light,the triplet excitons participating in phosphorescence emission come from the dual contribution of the ISC?S₁?T_n?process and direct S₀?T_n filling.When excited at long wavelengths,triplet excitons are only contributed by the direct spin-turned S₀?T_n process.Therefore,as the excitation wavelength increases,the phosphorescence gradually weakens.This work has certain significance in understanding the structure-effect relationship between the aggregation state structure and the phosphorescence properties,and the photophysical process of the phosphorescence.