Ruthenium-based metallacrown complexes for the selective detection of lithium ions in water and in serum by fluorescence spectroscopy

Fluorescent dihydroxypyridine ligands were prepared by attaching pyrene-, dansyl-, and methoxycoumarin-fluorophores via dimethyleneamine linkers. The reaction of these ligands with [(p-cymene) RuCl2](2) or [(C6H5CH2NMe2H)RuCl2](2)Cl-2 resulted in the formation of 12-metallacrown-3 complexes, which possess strong affinity for lithium ions. By a judicious choice of the fluorophore and the arene pi-ligand, a macrocycle was obtained that could be used in aqueous solution to selectively and quantitatively detect lithium ions by fluorescence spectroscopy.