A combinatorial approach to discover new chelators for optical metal ion sensing

This paper reports the synthesis and characterization of metal-binding indi cators with diverse optical responses on exposure to various heavy metal io ns. A combinatorial approach, based on azo coupling of diazonium salts with either phenolic compounds or aromatic amines, generated a library of azo d yes, Each reaction mixture, containing the product(s) of azo coupling, was incubated with a series of solutions, each containing a different heavy met al ion. The absorbance and, in some cases, fluorescence spectra of the resu lting complexes were recorded. The metal chelates showed extensive diversit y in their W-visible absorbance spectra upon binding to selected metal ions . Of the azo dyes prepared, the terdentate dyes were particularly useful, p roviding distinct spectral responses to three or more metal ions in a panel of seven.