Ramadan M. El-Bahnasawy

Iron(III), Cobalt(II), Nickel(II), Copper(II) and Zinc(II) Complexes of 4-Formylantipyrine Thiosemicarbazone

Abstract Complexes of iron(III), cobalt(II), nickel(II), copper(II) and zinc(II) with 4-formylantipyrine thiosemicarbazone (HFoAtsc) have been prepared and spectrally and physically characterized. IR, electronic, and ESR spectra of the complexes, as well as IR, electronic and 1H and 13C NMR spectra of HFoAtsc, have been obtained. The spectral studies show that HFoAtsc behaves as neutral or monobasic bidentate ligand in all complexes except [Fe(FoAtsc)2]ClO4 and [Co(HFoAtsc)2](BF4)2, where the thiosemicarbazone bonds in a monobasic tridentate fashion in the former and a neutral tridentate manner in the latter. Coordination takes place via the azomethine nitrogen and the thione or thiolato sulfur for bidentate coordination and the carbonyl oxygen of the pyrazolone ring is added for tridentate coordination. Referee I: N. V. Duffy Referee II: R. L. Musselman

Synthesis, magnetic and spectral studies of iron(III), cobalt(II,III), nickel(II), copper(II) and zinc(II) complexes of 2–formylpyridine N(4)-antipyrinylthiosemicarbazone

Abstract2–Formylpyridine N(4)-antipyrinylthiosemicarbazone and its metal complexes have been synthesized and characterized. Elemental analyses, molar conductivities, magnetic measurements and spectral (i.e., i.r., electronic, n.m.r. and e.s.r.) studies have been used to characterize the complexes. The i.r. spectra show that the thiosemicarbazones behave as bidentate or tridentate ligands either in the thione or thiolato form. Ligand field parameters have been calculated and the proposed stereochemistries are based on the various physical and spectral methods.

Copper(II) complexes of 4-formylantipyrine N(4)-substitutedthiosemicarbazones

Copper(II) complexes between three 4-formylantipyrine N(4)-substituted thiosemicarbazones and four copper(II) salts have been prepared and characterized. I.r., electronic and e.s.r. spectra of the complexes, as well as i.r., electronic and 1H and 13C-n.m.r. spectra of the thiosemicarbazones, have been obtained. Both mononuclear and binuclear complexes have been formed with bridging ligands for the latter, being either chloro or acetato. The stoichiometries of the complexes are dependent on both the steric requirements of the thiosemicarbazone ligands and the electronic effects of their N(4)-substituents.

Synthesis, magnetic and spectral studies of iron(III) and cobalt(II,III) complexes of 4-formylantipyrine N(4)-substituted thiosemicarbazones

The synthesis and characterization of complexes of iron(III), cobalt(II) and cobalt(III) with 4-formylantipyrine N(4)-methyl-, N(4)-dimethyl-, and 3-piperidylthiosemicarbazones are reported. Elemental analyses, molar conductivities, magnetic measurements and spectral (i.r., electronic and e.s.r.) studies have been used to elucidate the nature of the metal complexes. The i.r. spectra show that the thiosemicarbazones behave as bidentate or tridentate ligands, either in the thione or thiolato form. Different stereochemistries are proposed for the various cobalt(II) complexes on the basis of spectral and magnetic studies.

Synthesis, characterization and electrochemical properties of β-diketone complexes of ruthenium(III)

Abstract The reactions of ruthenium(III) chloride (1 mol) with acetylacetonylidene-4-aminoantipyrine (HL 1 ), monobenzoylacetylacetonylidene-4-aminoantipyrine (HL 2 ), dibenzoylmethanylidene-4-aminoantipyrine (HL 3 ) and antipyrine-4-azo-β-ethylacetoacetate (HL 4 ) (1 mol) produce complexes of the general formula RuHLCl 3 . The ligand antipyrine-4-azo-β-acetylacetone (HL 5 ) (1 mol) reacts with RuCl 3 ·3H 2 O to produce RuL 5 Cl 2 (H 2 O)·H 2 O. The ligands HL 1 -HL 3 react as neutral bidentates in the ketoenamine form, whereas HL 4 reacts as a neutral bidentate in the hydrazo form. HL 5 reacts as a monobasic tridentate in the azo form. The complexes were characterized using a variety of analytical, spectral, magnetic and thermal measurements. The electrochemical redox properties of complexes I–V have been studied by cyclic voltammetry in acetonitrile. The chloro-bridged dimer complexes I–IV showed two reversible diffusion-controlled oxidation peaks. The first was attributed to the oxidation of the ruthenium(III) to the corresponding mixed-valence complex and the second to the ruthenium(IV) complex. The redox properties of complexes I–IV are dependent on the nature of ligand. The monomeric complex V has quite different properties.

Membrane sensors for batch and flow injection potentiometric determination of ethamsylate (cyclonamine) in pharmaceutical preparations

The lipophilic nickel(II) and iron(II) bathophenanthroline derivatives of ethamsylate are used as ion-exchangers with high selectivity characteristics for ethamsylate. Poly(vinyl chloride) membrane sensors incorporating these electroactive materials display fast linear response for 1 × 10−1−1 × 10−4M ethamsylate under static and hydrodynamic modes of operation. In an acetate buffer of pH 4, the calibration slope is 51–53 mV/concentration decade and the lower limit of detection is 5.3 μg/ml. Except for salicylate and nitrate, most common anions, organic sulfonates, carboxylates, phenolates and various pharmaceutical excipients and diluents do not interfere. Determination of ethamsylate in various dosage forms shows an average recovery of 98.9% of the nominal and a mean standard deviation of 0.7%.

Synthesis, magnetic and spectral studies of nickel(II) and zinc(II) complexes of 4-formylantipyrine N(4)-substituted thiosemicarbazones

The synthesis and characterization of nickel(II) and zinc-(II) complexes with 4-formylantipyrine N(4)-methyl-, N(4)-dimethyl- and 3-piperidylthiosemicarbazones are reported. Elemental analyses, molar conductivities, magnetic measurements and spectral (i.r., electronic and n.m.r.) studies have been used to characterize the complexes. The i.r. spectra show that the thiosemicarbazones behave as bidentate or tridentate ligands, either in the thione or thiolato form. Stereochemistries are proposed for the complexes on the basis of spectral and magnetic studies.

o-hydroxyaroyl-isonicotinoyl hydrazones as chelating agents with divalent transition metal ions

SummaryTwo series of bivalent metal complexes of the type M(Sal)· xH2O and M(Naph) have been synthesized; where M = Co, Ni, Cu, Zn, Pd and Cd, and H2-Sal and H2-Naph are salicylaldehyde and o-hydroxynaphthaldehyde isonicotinoyl hydrazones which acted as dibasic terdentate ligands. The polymeric nature and coordination sites of the complexes have been characterized by elemental, d.t.a. and t.g.a analyses, molar conductance, pH, room temperature magnetic susceptibility and spectral (i.r., 1H n.m.r, u.v.) measurements. The protonation constants of the ligands have been determined potentiometrically at different temperatures, ionic strengths and at different EtOH-H2O compositions.

Benzoylacetone isonicotinoyl hydrazone complexes of divalent transition metals

SummaryBenzoylacetone isonicotinoyl hydrazone has been prepared in two forms: yellow (BzH2) and white (BzH2·H2O). Analytical, t.g.a., i.r. and n.m.r. results showed the yellow form to be a mixture of keto-enol tautomers, whereas the white form is a mixture of cis-trans enol tautomers. Complexes MBz (M = Ni, Cu, Zn and Pd), CoBz·H2O and Cd(BzH)2 have been isolated and characterized by physicochemical techniques.

Potentiometric determination of salicylhydroxamic acid (urinary struvite stone inhibitor) based on the inhibition of urease activity

Abstract A novel, sensitive and selective enzymatic potentiometric method for the determination of SHAM drug (salicylhydroxamic acid) is described. It is based on the fast and potent inhibitory action of SHAM on urease-catalyzed urea hydrolysis. The initial rate of the urea/urease reaction is potentiometrically monitored using an ammonia gas sensor. Effects of urease activity, urea substrate concentration, incubation time, temperature and pH are demonstrated. Under optimized conditions, there is a linear relationship between the degree of enzyme inhibition and SHAM concentrations over the range 0.5–7 μg ml −1 , with a 3σ detection limit of 0.1 μg ml −1 . Determination of SHAM in some pharmaceutical preparations shows an average recovery of 98% of nominal and a mean relative standard deviation of 1%. Drug decomposition products and metabolites (salicylic acid and salicylamide) do not interfere.