Synthesis, characterization and biological activities of metal(II) dipicolinate complexes derived from pyridine-2,6-dicarboxylic acid and 2-(piperazin-1-yl)ethanol

Abstract

The new water-soluble and air stable compounds (H(2)ppz)[Co(dipic)(2)]center dot 6H(2)O (1), (H(2)ppz)[Ni(dipic)(2)]center dot 6H(2)O (2) and (H(2)ppz)[Zn(dipic)(2)]center dot 6H(2)O (3) were prepared by the reaction of corresponding metal(II) acetates and a proton transfer salt, (H(2)ppz) (Hdipic)(2), (4) of pyridine-2,6-dicarboxylic acid (H(2)clipic) and 2-(piperazin-1-yl)ethanol (ppz). The compounds 1-3 were characterized by elemental, IR, UV-vis. thermal analyses, magnetic measurement and single crystal X-ray diffraction studies. The molecular structures of the title compounds consist of one 1-(2-hydroxyethyl)piperazine-1,4-diium (H(2)ppz(+2)) cation, one bis(pyridine-2,6-dicarboxylate)metal(II) [M(dipic)(2)](2-) anion, and six uncoordinated water molecules. In compounds 1-3 the metal ions coordinate to two oxygen and one nitrogen atoms of two pyridine-2,6-dicarboxylate molecules forming an octahedral environment. Antimicrobial activities against Gram (-) wild type (Escherichia coli and Pseudomonas aeruginosa), Gram (+) wild type (Staphylococcus aureus, Staphylococcus epidermidis, Bacillus cereus and Bacillus subtilis) and clinical isolate (Morganella morganii, Proteus vulgaris and Enterobacter aeruginosa) were also studied. The results were reported, discussed and compared with the corresponding starting materials ((H(2)ppz) (Hdipic)(2) (4), H(2)dipic and ppz). MIC (Minimal Inhibition Concentration) values of the newly synthesized compounds were determined as 4000 mu g/ml (except B. subtilis and clinical isolate E. aeruginosa, >4000 mu g/ml).