Synthesis, crystal structures, spectroscopic, and cytotoxicity study of Cu(II), Co(II), Ni(II) and Pd(II) complexes with 2-anilinomethylidene-5,5-dimethylcyclohexane-1,3-dione

Abstract The coordination compounds of Cu(II), Co(II), Ni(II) and Pd(II) with 2-anilinomethylidene-5,5-dimethylcyclohexane-1,3-dione (HL) of the composition [ML2(C2H5OH)2]·nH2O (M = Co (n=1), Ni (n=0)) and [ML2] (M = Cu, Pd) have been prepared and investigated by elemental analysis, IR-spectroscopy, NMR spectroscopy, powder X-ray diffraction analysis. Single-crystal X-ray diffraction analysis shows that HL serves as a chelate bidentate ligand coordinated to the metal ion through the N and O atoms forming a six-membered chelate ring. The coordination polyhedron of the metal atoms is a square bipyramid [ML2(C2H5OH)2] or square planar [ML2]. The Cu(II) and Pd(II) complexes stability in solution have been shown by NMR spectroscopy. The results of the cell viability study on Hep2 (human larynx carcinoma) cells demonstrates that the complexes don’t exhibit strong cytotoxic effect against Hep-2 cell line compared to cisplatin (IC50 = 9,2 ± 0,5 μM). Palladium(II) complex is the most cytotoxic among all complexes and shows IC50 value of 68,7 ± 5,3 μM.