Based On AIE Active Fluorescent Probe Of Benzothiazole Derivatives

Fluorescent probes offer individual advantages such as easy operation,simple equipment,low cost,excellent selectivity,high sensitivity,short response times and low detection limits.Hence,it is widely used in the detection of anions,cations,and biological macromolecules.However,the major issues that fluorescence sensor faced are aggregation caused quenching(ACQ),low water solubility,poor cell permeability.Aggregation-induced emission(AIE)overcomes the shortcomings of ACQ and expands the application of fluorescent probes.In this paper,the benzothiazole derivative fluorescent probes based on AIE effect were designed and synthesized.Then we have explored the optical properties and the proposed mechanism about the probes in aqueous solution.Moreover,the probes were applied to the imaging of biological cells.A novel fluorescence chemosensor 1 was synthesized with nucleophilic addition between 2-benzothiazoleacetonitrile and 4-(diphenylamino)-benzaldehyde and then characterized by nuclear magnetic spectrum,infrared spectrum,high resolution mass spectrometry and element analysisbased on the wide application of cyanide and extreme toxicity.It showed greater Stocks shift with 125 nm and strong AIE activity.1 exhibited prominent selective and sensitive detection to CN-in almost pure aqueous media and achieved a low detection limited of 0.22 ?M which was lower than the maximum level of cyanide in the drinking water(1.9 ?M)that the World Health Organization(WHO)permitted.According to the Job's plot,the binding ratio of 1 and CN-was 1:1.By the nuclear magnetic titration analyses,the conjugation was broken due to the nucleophilic addition of CN-to the vinyl group,the energy interior of molecule transferred,and further resulted in fluorescence quenching.In addition,1 could be made into fluorescent strip which was utilized to detect CN-in aqueous solution.More importantly,1 has potential for bioimaging in HeLa cells.As an important ROS ion,Hypochlorite widely present in daily life and human life.Appropriate amount of hypochlorous acid will help the body's own immune system regulation,excessive will cause a variety of diseases.Hence,a novel fluorescence probe 2 containing the large conjugate plane was designed and synthesized,where phenothiazine and benzothiazole were used as electron-donating group and fluorophore,respectively.The molecular structure of 2 was characterized by nuclear magnetic spectrum,infrared spectrum,high resolution mass spectrometry and element analysis.It exhibited a large Stocks shift of 174 nm and few molecular energy losses.Meanwhile,2 displayed extreme AIE activity and emited orange-red fluorescence in almost pure aqueous solution.2 exhibited turn-off fluorescence response to ClO-with detection limit of 0.64 ?M.Job's plot showed that the binding stoichiometry of 2 with Cl O-was 1:1.It was further suggested that ClO-oxidized the sulfur on the phenothiazine group into sulfoxide,resulting in fluorescence queching based on the observations of 1H NMR titration and high resolution mass spectrometry.In addition,2 was low cell toxicity,so ithas potential forcell imaging.