Ahmad Desoky M. Mohamad

Reactivity of base catalysed hydrolysis of 2-pyridinylmethylene-8-quinolinyl-Schiff base iron(II) iodide complexes: solvent effects

Three ligands of 2-pyridinylmethylene-8-quinolinyl (L1), methyl-2-pyridinylmethylene-8-quinolinyl (L2), and phenyl-2-pyridinylmethylene-8-quinolinyl (L3), Schiff bases were synthesised by direct condensation of 8-aminoquinoline with 2-pyridinecarboxaldehyde, 2-acetylpyridine, or 2-benzoylpyridine. They coordinated to Fe(II) ion in a 1: 2 mole ratio followed by treatment with iodide ions affording complexes with a general formula [Fe(L)2]I2·2H2O, (L = L1, L2, or L3). Spectrophotometric evaluation of the kinetics of base catalysed hydrolysis of these complex cations was carried out with an aqueous solution of NaOH in different ratios of water/methanol binary mixtures. Kinetics of the hydrolysis followed the rate law (k2[OH−] + k3[OH−]2)[complex]. Reactivity trends and their rate constants were compared and discussed in terms of ligand structure and solvation parameters. The methanol ratio affects the hydrolysis as a co-solvent which was analysed into initial and transition state components. The increase in the rate constant of the base hydrolysis of Fe(II) complexes, as the ratio of methanol increases, is predominantly caused by the strong effect of the organic co-solvent on the transition states.

Synthesis and characterization of novel bis(diphenylphosphino)-oxalyl and (substituted) malonyl dihydrazones: P,N,N,P-tetradentate complexes of an oxalyl derivative with Cu(II), Pd(II), and Mn(II)

Abstract Novel ligands of bis(diphenylphosphino)-oxalyl, malonyl, and methyl- and ethyl-malonyl dihydrazones were synthesized by condensation of oxalyl, malonyl, methyl-malonyl, and ethyl-malonyl dihydrazide with o-(diphenylphosphino)benzaldehyde in different conditions. The dihydrazones exhibit three different tautomeric structures detected by NMR and IR spectra. The 31P NMR spectrum demonstrates four different singlet signals, i.e., chemical shifts, of the three respective tautomers. Complexes of the oxalyl ligand with Pd2+, Cu2+, and Mn2+ ions are formed in 1:1 molar ratio. Their structures were characterized by IR, NMR, EPR, MS, EA, and TGA, in which the oxalyl ligand acts as a neutral P,N,N,P-tetradentate chelate. The pH stability of the complexes is in the region of ca. 4.5–7.5 and their activation energy was calculated from the conductivity measurements.Graphical abstract

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.

Polyhydrazide Incorporated with Thiadiazole Moiety as Novel and Effective Corrosion Inhibitor for C-Steel in Pickling Solutions of HCl and H2SO4

In this paper polyhydrazide incorporated with thiadiazole moiety (S5) was prepared and its chemical configuration was confirmed by spectroscopic methods (FTIR, 1H NMR, and 13C NMR). The inhibitive action of S5 polymer and its monomer 2,5-dihydrazinyl-1,3,4-thiadiazole (M1) on the C-steel corrosion in pickling acids solution was investigated by weight loss, potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) measurements. PDP method exhibited that the investigated polymer is mixed-type corrosion inhibitor in both acids (HCl and H2SO4). The data revealed that S5 compound is a good inhibitor for Csteel in studied acids, and protection efficiency (P%) follows this sequence: H2SO4<HCl. Also, it was found that, the P% of the S5 polymer is higher than that obtained for its monomer (M1). Adsorption of the titled polymer obeyed the isotherm of Langmuir and involves both chemical and physical adsorptions. Scanning electron microscopy (SEM) investigations established the protective layer formation from the studied polymer on the metal substrate and shield it from direct Cl- and/ or

Synthesis, characterization, DNA interaction, thermal and in vitro biological activity investigation of some Ni(II)-Isatin bishydrazone complexes

\rm{SO}_4^2-

Kinetics of the base hydrolysis of iron (II) complexes with pyridyl–quinolyl Schiff base ligands in aqueous and aqueous/methanol binary mixtures

SO42− attack.