Preparation And Properties Of Tetraphenylethene-basedand Aggregation-induced Emission Materials And Its Electrospun Luminescent Nanofibers

During the studies on the photophysical properties and applications of organic fluorescent molecules,a common phenomenon of fluorescence quenching(ACQ)that the molecular luminescence intensity and luminous efficiency sharply declining,which is usually resultedfrom a high molecular concentration or aggregation state.However,for the real application,the organic active materials are required to be made into aaggregation state,for examplesolid film,which greatly limits its applications.Conversely,the aggregation induced luminescence(AIE)phenomenon that the fluorescence of compounds is weak in the form of monomolecular or dilute solution,while strongin isthigh aggregative state.It is able to solve the problem of ACQ and provides a creative breakthrough in organic solid light-emitting field.At present,numerous materials with AIE characteristics have been designed and synthesized.Among them,tetraphenylether and their derivatives(tetraphenylethenes,TPEs)have attracted great attention due to their excellent luminescence performance,and simple preparation process.In this paper,a series of TPE-based AIE materials,including polymers and small molecules,werepreparedby using TPE as the core unit.The details are as follows.1.A series of phosphorescent TPE polymers were synthesized through Suzuk cross-coupling reaction by introducing the TPE structural unit to the main chain of iridium complex ploymers.The thermodynamic and photophysical properties of phosphorescent polymers were studied by controlling the typesand content of iridium complexes in the polymer.Meanwhile,the aggregation-induced luminescence properties of phosphorescent polymers were found to possese both effects ofAIE and ACQ..2.Using benzothiadiazole(BT)and DBT as electron acceptor units,triphenylamine and TPE as electron donor units,four kinds of compoundswith push-pull electronic structure,including TPE-BT-TPE,TPE-BTSe-TPE,TPA-BTSe-TPE and TPA-BTSe-TPE,were obtained.The effects of different electron acceptor and electron donor on the luminescence properties were investigated.3.TPE-DBT-TPE compounds were synthesized by using TPE as the nucleus and2,8-dibromo-dibenzothiophene(DBT)as the acceptor unit.The photophysical and electrochemical properties of the TPE-DBT-TPE were studied.Further,using PMMA as matrix polymer,TPE-DBT-TPE/PMMA composite nanofibers were prepared by electrospinning.The effects of fiber diameter and TPE-DBT-TPE concentration on the emission intensity,fluorescence quantum efficiency of composite nanofibers were also investigated.