Synthesis Of Fluorescent Probes Based On Triphenylamine With Aggregation Induced Emission Effects

pH and copper ions play an important role in the environment and various physiological activities of organisms,so the detection of pH and Cu2+is significant.However,most of probes have weak fluorescence in solutions of high water fraction,and aggregation induced luminescence(AIE)materials have strong fluorescence in the aggregation state or solid state,which can overcome the above disadvantages,so more and more researchers are concerned about it.In this paper,we desigined and synthesized four fluorescent probes based on triphenylamine,which can be devided into two parts.One part is the synthesis of pH fluorescent probes containing 2-(1H-Benzoimidazol-2-yl)-phenylamine.Another part is the synthesis of fluorescent probes by 2-Hydroxy-1-naphthaldehyde and 2-Hydroxy-1-acetylnaphthalene for bivalent copper ions with AIE effect.Firstly,two compounds(STPABI and DTPABI)were designed from triphenylamine and 2-(1H-Benzoimidazol-2-yl)-phenylamine.The two probes displayed aggregation-induced emission enhanced(AIEE)and crystallization-induced emission(CIE)effect.It mainly includes the following contents:First,they all showed the high fluorescence quantum yields(Φf)in both pure organic solvents and the aggregation state.Second,the luminophores emitted bluish violet fluorescence in organic solvents,and presented green emission in solid state.This tunable AIEE effect can be proved by intermolecular charge transfer using density functional theory(DFT)calculations.Third,the two compounds can serve as ratiometric pH probes.Fourth,the change in color between the blue violet and green on filter paper could be repeated by deprotonation and protonation indicating that can served as the fluorescent switching for volatile acidic and alkaline organic compounds.Secondly,two compounds(STPAPAH1 and STPAPAH2)containing triphenylamine were obtained by 2-Hydroxy-1-naphthaldehyde and 2-Hydroxy-1-acetylnaphthalene.The existence of methy had an effect on UV and fluorescence spectra by the research of photophysical properties.STPAPAH1 showed AIEE effect,while STPAPAH2 displayed the CIEE proporty.The difference was caused by the change of coplanarity using DFT calculations.According to recognition assay of different isons,the two probes can be used as probe for bivalent copper ions.The emission intensity of STPAPAH1 reduced to 45.35-fold and absorption band decreased to 1.69-fold with 6 nm.However,PL intensity of STPAPAH2 decreased to 38.24-fold and absorbance reduced to 2.54-fold.In addition,the recognition of Cu2+for STPAPAH1 and STPAPAH2 was reversible,and the change in colour under UV illumination from bright yellow to dark was visualized,which demonstrated the two probes can be used as naked eye probe for bivalent copper ions.pH effect,binding constant and limit of calculation indicated that STPAPAH1 has batter properties for detection of Cu2+ comparing with STPAPAH2.