Design,Synthesis And Properties Of Tetraphenylethylene-based Formaldehyde Fluorescent Probes

Formaldehyde(FA),an important chemical material,plays a significant role in many fields.However,as a common indoor pollutant,FA presents a serious threat to human health.Therefore,sensitive and efficient detection of FA is of great significance.Conventional methods for FA detection including chromatograph-based methods,spectrophotometer-based methods have some disadvantages such as high cost and complex operation,and greatly hinder their applications.In contrast,fluorescent probe overcomes these disadvantages,and has gradually developed into an important detection method.Up to now,many FA fluorescent probes have been developed.However,these reported FA fluorescent probes are almost aggregation-caused quenching-based probes.Such probes are solvent dependent and limited to detecting FA in solution.In contrast,aggregation-induced emission(AIE)probes have strong fluorescence in aggregate state.Therefore,AIE-based probes not only can be used to detect FA in solution,but also can be developed into fluorescent test plate to detect FA in the air.In this paper,we use tetraphenylethylene(TPE)as fluorophore and homoallylamine as reaction group to design two kinds of AIE-based FA fluorescent probes.(1)Probe TPE-FA-NH2 is designed by introducing homoallylamine into TPE molecule directly.TPE-FA-NH2 detects FA by 2-aza-Cope rearrangement reaction.Based on this mechanism,TPE-FA-NH2 not only can detect FA in acidic solution sensitively,specifically and quantitatively by fluorescence "Turn-on" response,but also can be developed into portable fluorescent test plate to detect FA in the air by ratiometric fluorescence response.(2)To obtain TPE-FA-NO2,fluorescence quencher moiety,4-nitrobenzyl,are incorporated into TPE-FA-NH2.Initially,TPE-FA-NO2 has weak fluorescence due to photoinduced electron transfer process between the 4-nitrobenzyl and fluorophore.However,after reacting with FA,weakly emissive TPE-FA-NO2 turms into a highly emissive eompound.Therefore,TPE-FA-NO2 can detect FA by a fluorescence "turn-on"response.Based on this mechanism,TPE-FA-NO2 can detect FA in acidic solution sensitively,specifically and quantitatively,but also can be developed into portable fluorescent test plate to detect FA in the air sensitively.As an AIE-based solid sensor for FA,portable fluorescent test plates enable safer and more convenient use and transport compared to solution-based sensors,and their market prospect is brighter.