Ternary Transition Metal Complexes with an Azo-Imine Ligand and 2,2'-Bipyridine: Characterization, Computational Calculations, and Acetylcholinesterase Inhibition Activities.

New mononuclear ternary transition metal complexes: [M(HL)(bipy)2]ClO4, (M: Mn(II) for 1, Ni(II) for 2), [M(HL)(bipy) (ClO4)], (M: Ni(II) for 3, Cu(II) for 4, Zn(II) for 5) with M(II), 2-[(E)-(hydroxyimino)methyl]-4-[(E)-phenyldiazenyl]phenol, H2L, and 2,2'-bipyridine were synthesized. The structures of the complexes were investigated by using various analytical, spectroscopic techniques such as elemental analysis, FTIR, UV-Vis, NMR, MALDI-TOF mass spectrometry, thermal analysis, and computational studies containing geometric optimizations and theoretical calculations of vibrations and electronic transitions. IR and thermal analysis data verifies the proposed structure of the complexes. The inhibition activities of the complexes against acetylcholinesterase (AChE) extracted from Ricania simulans adults and nymphs were examined and all the complexes were found to be active. Among the complexes studied, the most inhibition activity was exhibited by complex 5 with the lowest IC50 value (3.2±0.8) for AChE of adults, complex 3 with the lowest IC50 value (4.6±0.8) for AChE of nymphs.

Synthesis and spectroscopic studies of homo-binuclear, alkoxo bridged homo- and hetero-tetranuclear metal complexes of a bis-N2O4 Schiff base ligand derived from ethanolamine and macroacyclic tetranaphthaldehyde.

Three new homo-binuclear Ni(II), Cu(II), Zn(II) complexes (2-4), homo-tetranuclear Cu(II) complex (5), and hetero-tetranuclear Cu(II)-Ni(II) complex (6) of a macroacyclic potentially bis-hexadentate N2O4 Schiff base have been synthesized. The imino-alcohol ligand, H4L was obtained by the condensation of ethanolamine with 2,2'-[2,3-bis(1-formyl-2-naphthyloxymethyl)-but-2-ene-1,4-diyldioxy]bis(naphthalene-1-carbaldehyde). The structures of both the Schiff base and its complexes have been proposed by elemental analyses, spectroscopic data i.e. IR, 1H and 13C NMR, UV-vis, electrospray ionisation mass spectra, molar conductivities and magnetic susceptibility measurements. The ligand has two similar compartments to bind first primary two metal ions, and acts bi- or tetra-negative, bis-tetradentate forming five membered chelate ring. However, secondary two metal ions (either Cu2+ or Ni2+) are ligated with dianionic oxygen atoms of the alcohol groups and are linked to the 1,10-phenanthroline-nitrogen atoms in the tetranuclear complexes (5 and 6).

Synthesis, characterization and properties of tetra((1-hydroxyimino-methylnaphthalen-2-yloxy)methyl)ethene and its homo-dinuclear metal complexes: a combined experimental and theoretical investigation.

Tetra((1-hydroxyiminomethylnaphthalen-2-yloxy)methyl)ethene (THIMNYOME), H(4)L, was synthesized by the agents of 2-hydroxy-1-naphtaldehyde, tetra(bromomethyl)ethene and hydroxylamine hydrochloride in two steps. Characterization of THIMNYOME and its dinuclear complexes was made by elemental analyses, IR, (1)H- and (13)C NMR, UV-vis, electrospray ionisation mass spectra, molar conductivities and magnetic susceptibility measurements. In the light of these results, it was suggested that the ligand coordinate to each metal atom by the two ether oxygen, two nitrogen atoms of oxime imine (CN) and an axial oxygen of perchlorate to form pseudo square-pyramidal complexes with Ni(II), Cu(II) and Zn(II). Molar conductivity measurements reveal that all the complexes are non-electrolytes. In addition, the full geometric optimization of the tetraoxime ligand (4) has been made by the B3LYP/6-31G(d) level in order to establish a stable conformation. Additionally, all the complex structures have been studied in the B3LYP/LANL2DZ level. NBO charge distribution and the characteristics of frontier molecular orbitals of these complexes have also been investigated in order to see the electrons movement between ligand and metal atom in the same level.

Oxidative cleavage of DNA by homo- and heteronuclear Cu(II)-Mn(II) complexes of an oxime-type ligand.

Novel homodinuclear Cu(II) (K1), heterodinuclear Cu(II)-Mn(II) (K2) and homotrinuclear Cu(II) (K3) complexes with a novel oxime-type ligand have been prepared and their nucleolytic activities on pCYTEXP were established by neutral agarose gel electrophoresis. The analyses of the cleavage products obtained electrophoretically indicate that although the examined complexes induces very similar conformational changes on supercoiled DNA by converting supercoiled form to nicked form than linear form in a sequential manner as the complex concentration or reaction period is increased, K3 is less effective than the two others. The oxime complexes were nucleolytically active at physiological pH values but the activities of Kl or K2 were diminished by increasing the pH of the reaction mixture. In contrast, K3 makes dominantly single strand nicking by producing nicked circles on DNA at almost all the applied pH values. Metal complex induced DNA cleavage was also tested for inhibition by various radical scavengers as superoxide dismutase (SOD), azide, thiourea and potassium iodide. The antioxidants inhibited the nucleolytic acitivities of the oxime complexes but SOD afforded no protection indicating that the nucleolytic mechanism involves of copper and/or manganese complex-mediated reactive oxygen species such as hydroxyl radicals being responsible for the oxidative DNA cleavage.