Four diclofenac complexes with cobalt(II) and nickel(II) ions: Synthesis, spectroscopic properties, thermal decompositions, crystal structures, and carbonic anhydrase activities

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)2(3-pic)2] (1), [Ni(dicl)2(3-pic) 2(H2O)2] (2), [Co(dicl)2(2-aepyr) 2] (3), and [Ni(dicl)2(2-aepyr)2] (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)asym and (OCO)sym} 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.