Kojic acid derivatives as double face ligands for metal and phosphate ions.

A family of combined Kojic acid and polyamine derivatives has been synthesized as phosphate anion and metal ion ligands. The stoichiometry, stability and structure of the ion/ligand adducts were determined by 1H NMR spectroscopy, potentiometry, EXAFS and DFT calculations. The presented dual ligands bind effectively both phosphate anions and metal ions and could be used as effective ion receptors in challenging water conditions in the broad pH range. A careful analysis of the heatmaps of the stability constants allows to choose the most appropriate ligand for the ion for qualitative and/or quantitative analysis in water, without analyte pretreatment. Extremely high-water solubility (>0.6 M) and ion(s)/ligand stability of the adducts in the pH 3–11 are the greatest advantages of the presented here molecules over other known ion sensors. The presented here molecules represent an innovative class of dual metal/anion ligands, with perspective of medical and environmental use.