Structural and Electrochemical Studies of Cobalt(II) and Nickel(II) Coordination Polymers with 6-Oxonicotinate and 4,4′-Bipyridine

The 6-oxonicotinate (6-Onic) salts of a one-dimensional cationic cobalt(II) or nickel(II) coordination polymers with 4,4′-bipyridine (4,4′-bpy), namely {[Co(4,4′-bpy)(H2O)4](6-Onic)2·2H2O}n (1) and {[Ni(4,4′-bpy)(H2O)4](6-Onic)2·2H2O}n (2), were prepared hydrothermally by reactions of cobalt(II) nitrate hexahydrate or nickel(II) nitrate hexahydrate, respectively, 6-hydroxynicotinic acid and 4,4′-bipyridine in a mixture of ethanol and water. In the hydrogen-bonded frameworks of 1 and 2, the one-dimensional polymeric chains of {[M(4,4′-bpy)(H2O)4]2+}n (M = Co, Ni), the 6-oxonicotinate anions and the lattice water molecules were assembled via strong intermolecular O–H···O and N–H···O hydrogen bonds and π–π interactions, leading to the formation of the representative hydrogen-bond ring motifs: trimeric R23(10) motif, the centrosymmetric tetrameric R24(8) and R24(12) motifs and the pentameric R45(12) motif. The isostructural coordination polymers 1 and 2 exhibited a different electrochemical behavior, as observed by cyclic voltammetry, which can be attributed to the nature of the metal ions (cobalt(II) vs. nickel(II)).

Crystal structure of 1,1′-(pyridine-2,6-diyl)bis[N-(pyridin-2-ylmethyl)methanaminium] dichloride dihydrate

In the title compound, C19H23N5 2+·2Cl−·2H2O, the two pyridine side arms are not coplanar, with the terminal pyridine rings subtending a dihedral angle of 26.45 (6)°. In the crystal, hydrogen bonds, intermolecular C—H...Cl contacts and a weak C—H...O interaction connect the molecule with neighbouring chloride counter-anions and lattice water molecules. The crystal packing also features by π–π interactions with centroid-centroid distances of 3.4864 (12) and 3.5129 (13) Å.

Crystal structure of diaqua(3,14-diethyl-2,6,13,17-tetraazatricyclo[16.4.0.07,12]docosane)copper(II) dichloride tetrahydrate

The crystal structure of the novel hydrated CuII salt, [Cu(L)(H2O)2]Cl2·4H2O (L = 3,14-diethyl-2,6,13,17-tetraazatricyclo[16.4.0.07,12]docosane, C22H44N4) has been determined using synchrotron radiation. The asymmetric unit contains one half of the [Cu(L)(H2O)2]2+ cation (completed by crystallographic inversion symmetry), one chloride anion and two lattice water molecules. The copper(II) atom exists in a tetragonally distorted octahedral environment with the four N atoms of the macrocyclic ligand in equatorial and two O atoms from water molecules in axial positions. The latter exhibit a long axial Cu—O bond length of 2.7866 (16) Å due to the Jahn–Teller distortion. The macrocyclic ring adopts a stable trans-III conformation with typical Cu—N bond lengths of 2.0240 (11) and 2.0441 (3) Å. The complex is stabilized by hydrogen bonds formed between the O atoms of coordinated water molecules and the NH groups as donors, and chloride anions as acceptors. The chloride anions are further connected to the lattice water solvent molecules through O—H...Cl hydrogen bonds, giving rise to a three-dimensional network structure.

Synthesis, Characterization and Biological Studies on 3d-Metal Complexes of 5-[(1, 5-Dimethyl-3-oxo-2-Phenyl-2, 3-Dihydro-1H-Pyrazol-4-yl) Diazenyl]-1-Ethyl-6-Hydroxy-4-Methyl-2-oxo-1, 2-Dihydropyridine-3-Carbonitrile

N-hetorocyclic ligand. 5-[(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)diazenyl]-1-ethyl-6-hydroxy-4-methyl-2-oxo-1,2-dihydropyridine-3-carbonitrile (L) and a few of their transition metal complexes have been synthesised and characterized by different physico-chemical techniques. The electronic and magnetic susceptibility measurements suggest an octahedral geometry for all the complexes excepting Zn(II) complex which possess tetrahedral geometry. The results of thermogravimetric analysis showed that the synthesized complexes have thermal stability and confirms the absence of coordinated or lattice water molecules. The bio potency of all the compounds were investigated by studying the antimicrobial, antimycobacterial and cytotoxic activities. All the transition metal complexes were noticeably exhibited their inhibition properties against the tested microbes.