Nabawia M. Ismail

Synthesis, characterization, and biological activity of new mixed ligand transition metal complexes of glutamine, glutaric, and glutamic acid with nitrogen based ligands

ABSTRACT A new series of Cu(II), Co(II), Ni(II), and Fe(II) ternary complexes of glutamine, glutaric, and glutamic acid with imidazole derivatives have been synthesized. The nature of the bonding and the stereochemistry of the complexes have been deduced from elemental analyses, infrared and electronic spectra, conductivity measurements, and thermogravimetric analysis. The structure of [Co(glu)(IMI)2] and [Fe(glu)(IMI)2(H2O)2] complexes was validated using quantum mechanics calculations based on accurate DFT methods. Calculations revealed that both complexes had distorted tetrahedral geometry. In case of [Co(glu)(IMI)2], glu ligand was coordinated through the terminal part which consists of carboxylate and amine groups. The formation constants of mixed ligand complexes of copper (II) and nickel (II) with glutamic-glutamine-glutaric as primary ligands and imidazole or its derivatives as secondary ligands have been determined by pH metric technique in aqueous medium. The data obtained were used to evaluate the values of metal-ligand stability constants using Irving-Rossotti titration technique. Mixed ligand complexes studies of these metal ions have been carried pH-metrically at the same conditions. In addition, the interaction of these complexes with calf-thymus DNA (CT-DNA) was investigated at pH = 7.2 by using UV–vis absorption and viscosity measurements. Results indicated that the investigated complexes strongly bind to CT-DNA via intercalative mode. Moreover, the prepared compounds are screened for their in vitro antibacterial activity against two types of bacteria, Pseudomonas aeruginosa and Bacillus cereus. In general, based on the data obtained in this study, the synthesized metal complexes might be taken into consideration as promising antibacterial compounds.

Synthesis, characterization, anti-fungi and anti-bacterial activity of new [(2-pyridyl)-3-isatin]-bishydrazone

New [(pyridine-2-carboxaldhyde)-3-isatin]-bishydrazone (cpish), [(2-acetylpyridine)-3-isatin]-bishydrazone (apish), and [(2-benzoyl pyridine)-3-isatin]-bishydrazone (bpish) have been synthesized and characterized by the elemental analysis, IR, NMR and electronic spectra. The bioefficiency of the [(2-pyridyl)-3-isatin]-bishydrazones have been examined for their in-vitro antibacterial and antifungal activity against many types of bacteria and fungal cultures which are common contaminants of the environment in Egypt and some of which are involved in human and animal diseases or in plant diseases or frequently reported from contaminated soil, water, and food substances. The results of these studies indicate that the [(2-pyridyl)-3-isatin]-bishydrazones possess notable antimicrobial properties.

Synthesis and physico-chemical properties of some Ni(II) complexes with isatin-hydrazones

New Ni(II) complexes with bioactive bishydrazones ligands based on (pyridine-2-carboxaldhyde)-3-isatin, (2-acetylpyridine)-3-isatin, and (2-benzoylpyridine)-3-isatin have been synthesized and characterized by elemental analysis, conductivity measurements, IR and UV-Vis spectroscopy, and thermal analysis. The complexes stoichiometry and formation constants have been determined. The results suggest that isatinbishydrazones act as neutral tridentate ligands with ONN sites coordinating to the metal ion via isatin C=O, azomethine CR=N, and pyridine C=N groups to give [Ni(L)H2O]Cl2·2H2O, (L = neutral tridentate isatin hydrazone ligand). Kinetics and thermodynamic parameters of the complexes thermal decomposition have been elucidated from the thermal data using Coats and Redfern method, which has confirmed the first order kinetics.