Developments of selective chemosensors for the determination of heavy metal ions are very important in view of their extremely toxic impact on the environment and biological systems. We have prepared a series of bis-pyrenylacetamide derivatives based upon the molecular framework of 3,6-dioxaoctanedioic acid and investigated their fluoroionophoric properties toward transition metal ions.1 To have an insight into the structural effects on the chemosensing behavior, o-phenylenedioxydiacetic acid, 3,6-dithiaoctanedioic acid, and piperazine dicarboxylic acid derived analogues were also prepared. Prepared ionophores showed a prominent Hg2+-selective fluorescence signaling behavior over other tested transition metal ions by revealing characteristic fluorescence of pyrene functions in monomer and excimer regions.2 Among the prepared compounds, dioxodiacetamide derivative showed most pronounced selectivity toward Hg2+ ions compared with other congeners in aqueous methanol solution. The complex formation of the chemosensor with Hg2+ ions was supported by NMR, IR, and FAB mass spectral evidences. The fluoroionophore also exhibited Hg2+-selective fluorescence responses in simulated physiological solutions suggesting its practical applicability. The detailed fluoroionophoric behaviors of the compounds focusing on the optimization for selective chemosensing of Hg2+ ions will be presented.

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