Synthesis and Characterization of Bivalent Metal Complexes of Pyrrole-2-Carboxaldehyde Aroylhydrazones

N′-[(E)-Furan-2-ylmethylidene]-4-hydroxybenzohydrazide

The title compound, C₁₂H₁₀N₂O₃, exists in the E conformation. The five-membered ring and the phenyl rings form dihedral angles of 36.73 (10) and 12.22 (10)°, respectively, with the central C(=O)N₂C unit. The crystal packing is dominated by strong N—H⋯O and O—H⋯N hydrogen bonds. Together with weaker C—H⋯O inter­actions, these establish a three-dimensional supra­molecular network.

N′-[(E)-5-Bromo-2-hydroxy-3-methoxybenzylidene]benzohydrazide monohydrate

The title compound, C₁₅H₁₃BrN₂O₃·H₂O, exists in an E conformation with respect to the azo­methane C=N double bond. The benzene and phenyl rings form dihedral angles of 0.46 (2) and 4.90 (3)°, respectively with the central C(=O)N₂C unit. An intra­molecular O—H⋯N hydrogen bond occurs. In the crystal, some hydrazide mol­ecules are replaced by mol­ecules of the 6-bromo isomer. The Br atom from this admixture was refined to give a partial occupancy of 0.0443 (19). A supra­molecular network is built in the lattice by means of inter­molecular N—H⋯O and two O—H⋯O inter­actions together with non-classical C—H⋯O inter­actions involving the lattice water mol­ecule stacking the mol­ecules along the b-axis direction.

4-{(E)-[2-(Pyridin-3-ylcarbonyl)hydrazinylidene]methyl}phenyl acetate

The title compound, C₁₅H₁₃N₃O₃, exists in the E conformation with respect to the azo­methane C=N double bond. The pyridyl and phenyl rings form dihedral angles of 35.67 (8) and 36.65 (7)°, respectively with the central C(=O)N₂C unit. In the crystal, N—H⋯O and C—H⋯O hydrogen bonds connect the mol­ecules into chains along the b axis. Another C—H⋯O inter­action connects mol­ecules along the c-axis direction, forming layers.

Studies on antimicrobial activity of cobalt(III) ethylenediamine complexes

A series of cobalt(III) mixed ligand complexes of type [Co(en)2L]+3, where L is bipyridine, 1,10-phenanthroline, imidazole, methylimidazole, ethyleimidazole, dimethylimidazole, urea, thiourea, acetamide, thioacetamide, semicarbazide, thiosemicarbazide, or pyrazole, have been isolated and characterized. The structural elucidation of these complexes has been explored by using absorption, infrared, and 1H NMR nuclear magnetic resonance spectral methods. The infrared spectral data of all these complexes exhibit a band at 1450/cm and 1560–1590/cm, which correspond to C = C and C = N, a band at 575/cm for Co-N (en), and a band at 480/cm for Co-L (ligand). All these complexes were found to be potent antimicrobial agents. The antibacterial activity was studied in detail in terms of zone inhibition, minimum bactericidal, and time period of lethal action. Among all, complexes bipyridine, 1,10-phenanthroline, dimethylimidazole, and pyrazole, possess the highest antibacterial activity. Antifungal activity was done by disc-diffusion assay and 50% inhibitory concentrations that possess high antifungal activity.Key words: cobalt(III) complexes, ethylenediamine, antimicrobial, antifungal.