Four Diclofenac Complexes with Cobalt(II) and Nickel(II) Ions: Synthesis, Spectroscopic Properties, Thermal Decompositions, Crystal Structures, and Carbonic Anhydrase Activities

Abstract

Cobalt(II) and nickel(II) complexes with diclofenac (dicl) in the presence of nitrogen-donor 3-picoline (3-pic) and 1-(2-aminoethyl)pyrrolidine (2-aepyr), [Co(dicl)<inf>2</inf>(3-pic)<inf>2</inf>] (1), [Ni(dicl)<inf>2</inf>(3-pic) <inf>2</inf>(H<inf>2</inf>O)<inf>2</inf>] (2), [Co(dicl)<inf>2</inf>(2-aepyr) <inf>2</inf>] (3), and [Ni(dicl)<inf>2</inf>(2-aepyr)<inf>2</inf>] (4), have been synthesized and characterized by FT-IR, UV-Vis, elemental and thermal analysis. The crystal structures of 1 and 3 have been determined by single-crystal X-ray diffraction; phase purity of complexes has been proved by powder X-ray diffraction analysis. Structural analyses have demonstrated that 1 and 3 are mononuclear and Co(II) ions have distorted octahedral environments. In 1, dicl is bidentate, whereas in 2, 3, and 4 dicl is monodentate. Dicl ligands are coordinated to metal(II) ions with O of carboxylate. Therefore, IR spectra of all complexes display {(OCO)<inf>asym</inf> and (OCO)<inf>sym</inf>} of dicl. The calculated Δ(OCO) values are consistent with the presence of monodentate (>200) and bidentate (<200) carboxylate. Compounds 2, 3, and 4 exhibit inhibition effects on human carbonic anhydrase-I. Compounds 3 and 4 show high thermal stability compared with 1 and 2. © 2014 © 2014 Taylor & Francis.