Two novel Sm(III) complexes with different aromatic carboxylic acid ligands: Synthesis, crystal structures, luminescence and thermal properties

Two novel Sm(III) complexes, [Sm(3,4-DMBA)(3)(3,4-DMHBA)(5,5'-DM-2,2'-bipy)](2) (1), [Sm(3-MOBA)(3)(5,5'-DM-2,2'-bipy)](2) (2) (3,4-dimethylbenzoic acid = 3,4-DMHBA, 3-methoxybenzoic acid = 3-MOHBA and 5,5'-dimethyl-2,2'-bipyridine = 5,5'-DM-2,2'-bipy), have been successfully synthesized and assembled. The crystal structures were determined by single crystal X-ray diffraction. Two complexes were characterized by the elemental analysis, IR, powder X-ray diffraction, thermal gravimetric technology. Because of the different ligands, the structures of the two complexes are very different, especially the structure of the complex 1. Each central Sm(III) ion of complex 1 was coordinated by three deprotonated 3,4-DMBA(-),one unprotonated 3,4-DMHBA and one 5,5'-DM-2,2'-bipy, which has rarely been reported before. However each central Sm(III) ion of complex 2 was only coordinated via three deprotonated 3-MOBA(-) and one 5,5'-DM-2,2'-bipy. In addition, the thermal decomposition mechanism and the three-dimensional infrared accumulation spectra of the evolved gas during the thermal decomposition for two complexes were studied by the simultaneous TG/DSC-FTIR technology. What's more, the luminescence properties of two complexes were also discussed. Finally, the bacteriostatic activities of two complexes were evaluated against Staphlococcus aureus, Escherichia coli and Candida albicans. (C) 2018 Elsevier Ltd. All rights reserved.