Synthesis, structures and biological properties of nickel(II) phthalates with imidazole and its derivatives

Four new nickel(II) phthalate compounds: mononuclear complexes [Ni(Im)]6(Pht)·H2O (1), [Ni(Pht)(Im)3(H2O)2]·H2O (2) and [Ni(Pht)(2-MeIm)3(H2O)3]·H2O (3), and coordination polymer [Ni(Pht)(4-MeIm)2(H2O)]n (4) (where Pht = dianion of o-phthalic acid, Im = imidazole, 2-MeIm = 2-methylimidazole, 4-MeIm = 4-methylimidazole) have been synthesized. The complexes 1–4 were characterised by elemental analysis, IR data, thermogravimetric, and X-ray diffraction analyses. X-ray analysis shows that the asymmetric unit of 1 consists of [Ni(Im)]62+ cation, Pht2− anion and solvate H2O molecule. The phthalate dianion does not take part in coordination to metal ion. The cations, anions and water molecules are linked via   N–H⋯⋯O and O–H⋯⋯O interactions forming 2D hydrogen-bonded networks. The structures of 2 and 3 are similar to other mononuclear Ni(II) phthalate complexes where Pht2− anions act as monodentate ligands and uncoordinated carboxylate oxygen atoms participate in the formation of hydrogen bonded double-chains. The structure of 4 consists of [Ni(4-MeIm)2(H2O)] building units connected by phthalate ions to form helical chains. The complexes 1–4 were tested for their ability to increase the biosynthesis of enzymes.

Four new Ni(II) coordination compounds with o-phthalic acid and imidazole ligand and its derivatives such as 2-methylimidazole and 4-methylimidazole were synthesized and characterized by IR spectroscopy, thermogravimetric analysis, X-ray crystallography. The structural patterns displayed in 1–4 illustrate the rich binding facilities of carboxylate groups of the o-phthalate ligand and their ability to form extensive hydrogen-bonding interactions and building up supramolecular aggregates.Figure optionsDownload as PowerPoint slide