| Summary: | Rare earth complexes can exhibit higher coordination numbers while rare earth metals have the ability to form a multitude of geometries with organic ligands. The ligands, [Sm(III) (4Acpy4MTSC)2(4H2O)Cl]Cl2and [Sm(III) (4Acpy4ETSC)(5H2O)Cl2]Cl [4Acpy4MTSC = 4-acetylpyridine 4-methyl-3-thiosemicarbazone; 4Acpy4ETSC = 4-acetylpyridine 4-ethyl-3-thiosemicarbazone] have been synthesised by condensation method. The compounds were structurally characterised by elemental analysis (CHNS), molar conductivity, Fourier Transform Infrared (FT-IR), Nuclear Magnetic Resonance (NMR), Ultraviolet-Visible (UV-Vis), and Thermo-Gravimetric Analysis (TGA). The elemental analysis for the compounds were in a good agreement with the theoretical values. The molar conductivity of the complexes showed electrolyte behaviour and confirmed the presence of counter ions in the structures. The proposed structures of the compounds have been confirmed by NMR, UV-Vis, and TGA. Based on the analysis, the ligands were coordinated to the metal ions through azomethine N and thione S thus, producing bidentate complexes. From the TGA, it is confirmed that a few water molecules have coordinated with metal ions. The X-ray crystallographic structures for the 4Acpy4ETSC, the C=S bond length is shorter than the single bond C-S which is 1.82 Å. It shows that in the solid state, the ligand exists in the thione form. The 4Acpy4ETSC adopted a monoclinic system, a = 10.5922(7), b = 8.9597(6), c = 13.0407, Z = 4. In vitro antibacterial tests showed that the complexes have an effective inhibitory effect compared to the ligands because the presence of chloride ions, Cl-which caused the complexes to be more acidic, can inhibit bacterial growth. © 2017, Malaysian Society of Analytical Sciences. All rights reserved.
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