New fluorescence chemosensors comprised of ethynylarene fluorophore units and carboxylate analyte-recognition units were prepared via efficient two-step reaction sequences.  Sonogashira coupling between a variety of haloarenes and 3-ethynylaniline resulted in diamino- and triaminophenylethynylarene intermediate products.  Condensation with each of three different cyclic anhydrides (succininc, glutaric and diglycolic anhydrides) produced a family of dicarboxylated and tricarboxylated small molecule sensors.  High-throughput fluorescence binding assays allowed rapid screening of this family of arenes against various metal chloride salts in pH 7.5 TRIS-HCl aqueous buffer.  Dicarboxylated analogs detected Zn(II), Cd(II) and Pb(II) while not signaling an interaction with Ca(II), Mg(II), Hg(II), Co(II), Cu(II) or Sr(II).  Fluorescence responses were dependent on ethynylarene regioisomer identity, with meta isomers displaying solution-phase bathochromic shifts in fluorescence signals, while para isomers produced fluorescent precipitates.  Tricarboxylated sensor output varied significantly with carboxylate analyte-recognition unit identity.  Details of the preparation, characterization and high-throughput fluorescence assays will be presented.

Development of carboxylated ethynylarenes as fluorescent chemosensors for divalent cations in aqueous solution

243rd National Meeting (2012)

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