Lanthanide bindings of phenanthroimidazole-based clicked cage-ligands; designed by schiff base condensation

Phenanthroimidazole-based cage-ligands 1 and 2 and their Eu(III), La(III) lanthanide complexes were synthesized and characterized. Schiff base condensation is the main step to obtain cage-shaped ligand design. Connection between clicked-phenanthroimidazole dipodal aldehyde and a fluorescent amine resulted great numbers of possible bindings that make the cage-shaped ligands suitable for lanthanide bindings. Lanthanide selectivities of the ligands 1 and 2 were investigated towards Dy(III), Yb(III), Er(III), Tb(III), La(III) and Eu(III) ions by absorption and emission studies in half-aqueous medium. The binding stoichiometries with the most fluorescence quenching ion Eu(III) were determined by Job's plotting as 1:1 ratio between ligand/Eu(III). The binding constants were calculated as 1.074 × 104 M−1 for 1 and 6.67 × 103 M−1 for 2 according to the concentration studies and the limit of detections (LOD) were determined as 5.23 × 10−4 μM for 1 and 4.65 × 10−4 μM for 2 by Benesi-Hildebrand plotting. •Phenanthroimidazole-based cage-ligands 1and 2and their Eu(III), La(III) lanthanide complexes were synthesized and characterized.•Lanthanide selectivities of the ligands 1and 2were investigated towards Dy(III), Yb(III), Er(III), Tb(III), La(III) and Eu(III) ions by absorption and emission studies in half-aqueous medium.•The binding stoichiometries with the most fluorescence quenching ion Eu(III) were determined by Job’s plotting as1:1 ratio between ligand / Eu(III).