Crystal structures, thermal behavior and biological activities of lanthanide compounds with 2,4-dichlorobenzoic acid and 1,10-phenanthroline

Five new binuclear lanthanide compounds [Ln(2,4-DClBA)(3)phen](2) (Ln = Pr(1), Eu(2), Tb(3), Ho(4) and Er(5); 2,4-DClBA = 2,4-dichlorobenzoate; phen = 1,10-phenanthroline) have been synthesized and structurally characterized by X-ray crystallography. And all of them were carefully investigated by elemental analysis, molar conductance, IR, UV and TG/DSC-FTIR technology. Single-crystal X-ray diffraction studies revealed that compounds 1-5 were binuclear molecules with an inversion center and the Ln(3+) ions contained two kinds of coordination environment that was a distorted monocapped square-antiprism in the compounds 1-2, and a distorted square-antiprism geometry in the compounds 3-5. The 3D surface graphs for the FTIR spectra of gaseous products for the compounds 1-5 were recorded using simultaneous TG/DSC-FTIR technique which is intended to further analysis of the thermal decomposition processes. Hence the gaseous products were identified by the solved single IR spectra obtained at different temperatures from the 3D surface graphs. Furthermore, the Eu(III) and Tb(III) ternary compounds exhibited intense luminescence under the radiation of UV light. And the results for antimicrobial test show that these compounds exhibit good bacteriostatic activity against Staphylococcus aureus, and better antimicrobial activity against Escherichia coli and Candida albicans.