Wafaa M. Hosny

Equilibrium and hydrolysis of α-amino acid esters in mixed-ligand complexes withN-(acetamido)-iminodiacetatecopper(II)

SummaryThe formation equilibria of the binary and ternary complexes of CuII withN-(acetamido)-iminodiacetic acid (ADA) and amino acids or their esters were investigated potentiometrically. The chelation mode was ascertained by conductivity measurements. The kinetics of the base hydrolysis of amino acid esters in the presence of the copper(II)-ADA complex were studied. The rate and catalysis constants were estimated.

Metal Chelates with Some Cellulose Derivatives: V. Synthesis and Characterization of Some Iron(III) Complexes with Cellulose Ethers

Two types of monoligand complexes of FeCl 3 , Fe(NO 3 ) 3 and Fe 2 (SO 4 ) 3 with hydroxyethyl cellulose (HEC) and carboxymethyl cellulose (CMC) were prepared and characterized. Elemental analysis, UV and IR spectroscopies, conductance and magnetic measurements were used to assign the mode of coordination in the isolated species. The investigation revealed that Fe(III) exhibits tetrahedral coordination with HEC and CMC. These ligands act as a bidentate chelating agent via the two oxygen atoms of the vicinal hydroxyl and ether groups (ethoxyl or carboxymethyl groups). The prepared complexes have the formula [(HEC) FeCl]Cl, [(HEC) FeNO 3 ]NO 3 , [(HEC)FeSO 4 .H 2 O]H 2 O, [(CMC)FeCl . H 2 O]Cl . 2H 2 O, [(CMC)Fe 2NO 3 ]3H 2 O and [(CMC)-FeSO 4 .H 2 O]H 2 O. The results also showed that the type of cellulose ether (functional group) and the anion of the metal salts used have an effect on the conductivity, structure and absorptivity of Fe(III) complexes.

Metal Chelates with Some Cellulose Derivatives. II. Preparation and Characterization of Co(II)-CMC Complexes

Abstract Complexes of three grades of sodium carboxymethyl cellulose (CMC) with cobalt(II) chloride have been prepared and characterized by elemental analysis, magnetic measurements, and infrared (IR) and electronic spectroscopy. The studies revealed that CMCs react with cobalt(II) in the stoichiometric ratio 1:1 (metal ion:ligand). The ligand field parameters of the octahedral Co(II) complexes were calculated. The stability of these complexes was studied in DMF medium using spectrophotometric methods. The optimum conditions favoring complex formation are critically evaluated.

Equilibrium studies of the binary and ternary complexes involving tetracycline and amino acid or DNA constituents

The acid-base equilibria of tetracycline and its copper(II) complex formation equilibria are investigated in dioxane-water mixtures. The ternary complexes of copper(II) with tetracycline as primary ligand and amino acid or DNA constituent as secondary ligand are studied in 50% dioxane-water solution. The formation constants of the ternary and binary complexes with amino acids or DNA constituents are determined. The concentration distribution of the various complex species are evaluated. Probable mode of chelation with tetracycline and DNA constituents is discussed.

Mixed ligand complexes of palladium(II) with diethylenetriamine as a primary ligand and amino acids as secondary ligands

SummaryEquilibrium studies of mixed ligand complexes of palladium(II) containing diethylenetriamine as a primary ligand and amino acids as secondary ligands were made by the pH titration method at 25° C and ionic strengthM=0.1. Different equilibrium constants, characteristic of binary and mixed ligand complexes were calculated and the chelation mode was deduced from conductivity measurements.

Coordination properties of N,O-carboxymethyl chitosan (NOCC). Synthesis and equilibrium studies of some metal ion complexes. Ternary complexes involving Cu(II) with (NOCC) and some biorelevant ligand

In the present study, the acid-base equilibria of N,O-carboxymethy chitosan abbreviated as (NOCC), is investigated. The complex formation equilibria with the metal ions Cu(II), Ni(II), Co(II), Mn(II), and Zn(II) are investigated potentiometrically. The stability constant values of the binary and ternary complexes formed in solution were determined and the binding centers of the ligands were assigned. The relationships between the properties of the studied central metal ions as ionic radius, electronegativity, atomic number, and ionization potential, and the stability constants of the formed complexes were investigated in an effort to give information about the nature of chemical bonding in complexes and make possible the calculation of unknown stability constants. Cu(II), Ni(II), and U(VI) complexes with NOCC are isolated as solid complexes and characterized by conventional chemical and physical methods. The structures of the isolated solid complexes are proposed on the basis of the spectral and magnetic studies. The ternary copper(II) complexes involving NOCC and various biologically relevant ligands containing different functional groups, as amino acids and DNA constituents are investigated. The stability constants of the complexes are determined and the concentration distribution diagrams of the complexes are evaluated.

Synthesis and Equilibrium Studies of the Metal Complexes of 4-Amino-N-(2,6-dimethyl-4-pyrimidinyl)-benzenesulfonamide (Sulphadimidine)

Abstract The formation equilibria of the complexes of some transition metal ions with sulphadimidine (SDD) have been investigated by a potentiometric technique. The stepwise formation constants of the complexes formed in solution were calculated using the non-linear least-squares computer program MINIQUAD. The concentration distribution of the complex species was determined. Complexes of Cu(II), Cr(II), Ni(II), Co(II), Zn(II), Hg(II), Cd(II), UO2(VI) and Pd(II) have been synthesized and characterized by elemental analyses, electrolytic conductance, electronic, IR, 1H NMR, and mass spectra and thermogravimetric studies. The ligand forms 1:1 complexes (metalion: ligand) with Cu(II), Zn(II), Hg(II), Cd(II), UO2(VI) and Pd(II) and 1:2 complexes with Cr(III), Ni(II) and Co(II). Referee I: P. R. Singh Referee II: F. R. Johnston

Coordination Compounds of Uranyl(II) Ion with Some Selected Antibiotics

Abstract The formation of the complexes between uranyl(II) ion with ampicillin, cephalexin and cephradine has been investigated using potentiometric technique. The stability constants of the complexes formed were calculated using the non-linear least-square computer program MINIQUAD. The uranyl(II) complexes with the antibiotics were synthesised and characterized by elemental analyses, conductivity and IR spectroscopy. From theses studies it is proposed that the antibiotic acts as a bidentate ligand and is bound to the metal ion through the carbonyl and the amino groups of the side chain.

Coordination properties of cefadroxil antibiotic: synthesis and equilibrium studies of the binary and ternary complexes involving amino acids and DNA units.

The formation equilibria for the binary complexes of Cu(II), Ni(II), Co(II), Zn(II), Mn(II), Hg(II), Cd(II), Ca(II), and Mg(II) with cefadroxil (Cef) and for the ternary complexes Cu(Cef)(L), where L refers to amino acid or DNA, were investigated. The protonation constants of cefadroxil and formation constants of the formed complexes were determined at 25 degrees C and mu = 0.1 M NaNo(3). Cooper(II) and cobalt(II) complexes of cefadroxil were isolated in solid state and characterized by elemental analysis, infrared and electronic spectral, conductivity and magnetic measurement.

Metal chelates with some cellulose derivatives; part IV. Structural chemistry of HEC complexes

Reactions of hydroxyethyl cellulose (HEC) with CrIII, NiII, CoII, or CuII chlorides in aqueous medium yielded complexes with formulae [M(HEC)Clm.nH2O], wherem=1 or 2 andn=2 or 3. HEC acted as a uninegatively charged bidentate ligand in the case of CrIII and NiII, and as a neutral ligand in the case of CoII and CuII complexes. The spectra showed that the binding sites in CrIII and NiII complexes were the ether oxygen between two ethoxyl groups and the oxygen of the hydroxyl group; while in the CoII and CuII complexes the binding sites were the oxygen of ethoxyl groups and the primary alcoholic O atom of glucopyranose rings. These complexes would most likely exhibit octahedral geometry with CrIII, NiII, and CoII, but square planar configuration in the case of the CuII complex. The ligand parameters of the CrIII, NiII, and CoII metal chelates were calculated in different solvents and at different temperatures. The thermal stability of the above complexes was investigated and the overall thermodynamics functions ΔG0, ΔH0, and ΔS0, associated with complex formation, were estimated.