Synthesis, crystal structure and NMR investigation of novel Ca(II) complexes with heterocyclic alcohol, aldehyde and carboxylate ligands. Evaluation of Ca(II) and Cd(II) analogues for anticancer activity

Three new calcium(II) complexes with heterocyclic alcohol (2-hydroxymethylpyridine), aldehyde (4-methyl-5-carbaldehydeimidazole) and carboxylate (picolinate, obtained in situ) moieties were synthesised and characterised using elemental analysis, X-ray, IR (Raman), 1H, and 13C NMR methods. In addition, we compared the X-ray results obtained for calcium(II) complexes with the structures of previously described cadmium compounds, which from the chemical point of view (HSAB and Lewis acids and bases theories) can give some information for the ability of Cd2+ to mimic Ca2+ ions in biological systems too. The studied ligands, calcium compounds (1–3) and cadmium analogues were tested for their cytotoxicity against HeLa (cervical carcinoma), K562 (leukaemia) and normal cells (HUVEC) using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.