A multi-functionalized ligand, based on a glutamic acid skeleton, bearing phenanthroline carboxylic units as chromophores and chelating arms has been designed. A base-assisted bis N-alkylation of dimethyl glutamate hydrochloride with the pivotal 2-carbomethoxy-4-methoxy-9-bromomethyl-1,10-phenanthroline building block, followed by a saponification step, provided the target ligand as its tetrahydrochloride salt. The spectroscopic properties of the ligand and its lanthanide(III) complexes were investigated in aqueous 0.01 M TRIS/HCl buffer at pH 7.0. The europium(III) complex was highly luminescent, exhibiting a quantum yield of 6% despite the presence of ca. one molecule of water in the first coordination sphere, whereas the terbium(III) complex was only weakly luminescent.
phenanthroline - carboxylate - lanthanides - luminescence
