Synthesis of novel fluorescent sensors based on naphthalimide fluorophores for the highly selective Hg2+-sensing

With an aim to develop the new sensors for optical detection of hg2+ ions,two novel fluorometric sensors were designed and successfully prepared using 2-(3-(2-aminoethylsulfanyl)propylsulfanyl)ethanamine and one or two n-methylnaphthalimide moieties (1 and 2). sensor 1 was obtained via n-alkylation,n-imidation and a one-pot nucleophilic aromatic substitution,and n-formylation of the amine,while sensor 2 was prepared via n-alkylation,n-imidation,and nucleophilic aromatic substitution. the characterization,including 1h nmr,13c nmr,and mass spectrometry,was then performed for 1 and 2. the hg2+-binding behaviors of the sensors were investigated in terms of sensitivity and selectivity by fluorescence spectroscopy. sensor 1 especially provided the reversible and highly hg2+-selective on-off fluorescence behavior by discriminating various interfering ions such as pb2+,co2+,cd2+,mn2+,fe2+,k+,na+,and in particular cu2+ and ag+ with a detection limit of 22 ppb toward hg2+ ions. © 2015 yordkhuan tachapermpon et al.