Preparation And Performance Of Water-soluble Chemosensor For Detection Of Metal Ions

Metallic materials have been widely used in daily life and industry.With the increase of acid rain,the pollution of water environment caused by metal ions is increasing seriously.Metal ions could enter human body through the ecosystem and food chain,and various diseases have been induced by the accumulation of metal ions in human body.Therefore,the highly effective detection of metal ions has significant importance for environment protection and human health.The traditional detection methods such as voltammetry,graphite furnace atomic absorption spectrometry and inductively coupled plasma atomic emission spectrometry,have been widely used for the detection of metal ions.However,their disadvantages including complex sample preparation,expensive instruments and complex operation procedures,limit their potential applications.Recently,great attention has been paid to the development of chemosensors for metal ion detection due to their easy operation,excellent selectivity and sensitivity,cost effectiveness and real-time monitoring with rapid response.However,most of chemosensors only could worke well in co-solvents of water and organic solvent or even in pure organic solvents for sensing metal ions,which limited their practical applicability in water environment and biological system.Based on the above background,we designed and synthesized a series of water-soluble chemosensors baesd on polymer modification,reversible addition-fragmentation chain transfer（RAFT）copolymerization and micelle assisted method.The main contents are summarized as follows:1.Five functionalized polyethylene glycol（PEG）,naphthalene-based Schiff base terminated PEG（PEGBN）,salicylaldehyde-based Schiff base terminated PEG（PEGBAB）,benzoylhydrazine-based Schiff base terminated PEG（PEGBHB）,rhodmine B derivative terminated PEG（PEGSRh）and fluorescein derivative terminated PEG（PEGSFl）,were synthesized by the strategy of polymer modification.All polymers exhibited excellent solubility in water.As the chemosensors,the selectivity toward metal ions was investigated by UV-vis absorption and fluorescence spectroscopy.PEGBN,PEGBAB and PEGBHB exhibited high selectivity and sensitivity toward Al³⁺over other competitive metal ions in100%aqueous solution,while PEGSRh and PEGSFl could serve as dual chemosensors and sense efficiently Cu²⁺and Hg²⁺in pure aqueous solution.Furthermore,test papers coated with PEGBAB,PEGBHB,PEGSRh and PEGSFl respectively were fabricated facilely for convenient and visual detection of Al³⁺or Cu²⁺and Hg²⁺.2.Furan based-Schiff base functionalized polymer P（NIPAM-co-AFB）were designed and synthesized by RAFT copolymerization of NIPAM and furan based-Schiff base monomer.P（NIPAM-co-AFB）could solve directly in water.The selectivity of P（NIPAM-co-AFB）toward metal ions was also studied by UV-vis absorption and fluorescence spectroscopy.The results indicated that P（NIPAM-co-AFB）showed excellent selectivity and sensitivity for the detection of Al³⁺,and the reversibility of chemosensor was proved by alternate addition of Al³⁺and EDTA to P（NIPAM-co-AFB）solution.3.The chemosensor ESB/SDS was designed and synthesized by micelle assisted method with Schiff base derivative（ESB）as recognition group and sodium dodecyl sulfate（SDS）as carrier.The particle size of ESB/SDS was measured by nano particle analyzer in the absence and presence of Al³⁺.The selectivity of ESB/SDS toward metal ions was studied by fluorescence spectroscopy.ESB/SDS showed high selectivity and anti-interference for sensing Al³⁺.Furthermore,ESB/SDS could recognize Al³⁺in a wide p H range.