Synthesis of high purity pyridine-phenolic ligands for metal ion optical sensors

A refined synthesis and facile purification process have been developed to access pyridine-phenolic ligand derivatives in high purity and yield, which are needed for optical detection of low levels of metal ions in biological and environmental sensor applications. The two-step process employs Suzuki coupling and demethylation, and the purification is facilitated by an acid/base extraction protocol that allows for significant impurities to be removed without the need for conventional gradient chromatography. These amphoteric ligands exhibit unique physical, chemical, and spectroscopic properties and are of interest in the complexation of metal ions. The simplest pyridine-phenolic compound, 2-(2'-hydroxyphenyl)pyridine, is shown to have potential as a switch-on fluorescence ligand for beryllium ions under aqueous conditions.