Four Ca(II)-Ln(III) bimetallic luminescent coordination polymers for sensing Fe(III) ions

We successfully prepared four Ca(II)-Ln(III) bimetallic complexes using rare earth metal (Eu, Tb) and alkaline earth metal Ca(II) under solvothermal conditions. A series of characterizations, such as XRD, IR, TGA, and solid-state fluorescence were carried out on these six crystalline materials. The single crystal test shows that all complexes are three-dimensional structures. The stability of the complex in H2O, MeOH, EtOH, and DMF solutions was studied. And the sensing effect of these complexes on metal ions (Fe2+, Cu2+, Cd2+, Mg2+, Ni2+, Co2+, Ca2+, Ba2+, Sr2+, Li+, Na+, K+, Al3+, Pb2+, Cr3+, Mn2+ and Zn2+) in aqueous solutions was studied. The results indicate that Fe(III) ions have a fluorescence quenching effects on 1-4, with high selectivity and sensitivity. The KSV values of the complexes 1-4 for Fe(III) ions are 1.77×105 (1), 6.35×104 (2), 2.25×105 (3), 5.41×104 (4), respectively, which indicated that 1-4 could be used as a fluorescent sensor for selective detection of Fe(III) ions.