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
