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排序方式: 共有104条查询结果,搜索用时 171 毫秒
41.
Mohamed R. Shehate Mohamed M. Shoukry Mona S. Ragab 《Central European Journal of Chemistry》2012,10(4):1253-1261
The Pd(DMPA)Cl2 complex, where DMPA = N,N-dimethylaminoproylamine, was synthesized and characterized. The stoichiometry and stability constants of the complexes formed between various dicarboxylic acids and [Pd(DMPA)(H2O)2]2+ were investigated. The effect of solvent dielectric constant, chloride ion concentration of the medium and temperature on the stability constant of the cyclobutanedicaroxylic acid (CBDCA) complex was investigated. The equilibrium constants for the displacement of coordinated CBDCA by inosine, taken as an example of DNA constituents, were calculated. The results are expected to contribute to the chemistry of antitumour agents. 相似文献
42.
43.
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. 相似文献
44.
Phenylephrine (PE) ion-selective electrode based on incorporation of phenylephrine-tetraphenylborate lipophilic salt in plasticized PVC matrices is constructed. The electrode shows near Nernstian response over the concentration range 1.5 × 10–4-10–1
M in solutions of pH 2.9–8.0 at 25°C. The electrode resists the effect of heat in the temperature range 25–55°C exhibiting an isothermal temperature coefficient of 0.0007 V/°C. The selectivity of the electrode for PE towards large number of inorganic cations, sugars and amino acids is investigated. Determination of PE in an eye-drops pharmaceutical preparation is carried out using the proposed electrode as potentiometric sensor. 相似文献
45.
Summary The 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. 相似文献
46.
M. M. Shoukry S. M. El-Medani M. M. Khatab 《Monatshefte für Chemie / Chemical Monthly》1996,127(8-9):811-820
Summary The acid-base equilibria of propane 1,2,3-triamine (PTA) and the formation equilibria of binary and ternary complexes of palladium(II) withPTA as primary ligand and amino acid, peptide, and DNA subunits as secondary ligand have been investigated. Pd(II) is found to form a 1:1 complex withPTA. The ternary complexes are formed in a stepwise mechanism, wherebyPTA first binds to Pd(II) and then ligates to the secondary ligand. The hydrolysis of the Pd-PTA complex and the deprotonation of the amide residues in the peptide complexes are discussed in relation to physiological conditions.
Gemischte Palladium(II)-Komplexe mit Propan-1,2,3-triamin als Primärligand und Aminosäuren, Peptiden oder DNA-Einheiten als Sekundärliganden
Zusammenfassung Das Säure-Basen-Gleichgewicht von Propan-1,2,3-triamin (PTA) und die Bildungsgleichgewichte von binären und ternären Komplexen von Pd(II) mitPTA als Primärligand und Aminosäuren, Peptiden und DNA-Einheiten als Sekundärliganden wurden untersucht. Pd(II) bildet mitPTA einen 1:1-Komplex. Die ternären Komplexe werden stufenweise gebildet, wobeiPTA zuerst an Pd(II) koordiniert; dann erfolgt die Bindung an den Sekundärliganden. Die Hydrolyse des Pd-PTA-Komplexes und die Deprotonierung der Amide in den Peptidkomplexen werden im Zusammenhang mit physiologischen Bedingungen diskutiert.相似文献
47.
New complexes of N-2-[3-methylpyridyl]-N-phenylthiourea (HMPyPT) have been prepared from NiII, CuII, ZnII, PdII, PtIV and AuIII chlorides. Three types, containing 1:1, 1:2 and 1:3 metal–ligand ratios, were isolated and characterized. In every case the ligand behaves in a monodentate manner coordinating via the pyridyl nitrogen. Attempts to isolate complexes containing the deprotonated ligand by raising the pH of the reaction mixture from 1.6–5.5 to 8.5 were unsuccessful. The bonding modes and the stereochemistry of the metal complexes have been determined from spectral (i.r., u.v.–vis., 1H-n.m.r.) and magnetic measurements. The results suggest a square-planar structure for the PdII and AuIII complexes, but octahedral geometry for the other metal complexes. Thermal analysis (d.t.a., t.g.a.) measurements on the solid complexes have also been conducted. 相似文献
48.
Mohamed M. Shoukry Ihsan M. Kenawy Afkar K. Abdel Hadi Eman M. Shoukry 《Journal of Chemical Sciences》1988,100(5):381-388
The formation constants of salicyl-4-amino-2,3-dimethyl-1-phenyl-3-pyrazoline-5-one (SAAP) complexes with 3d transition metal
ions [Cu(II), Ni(II), Co(II), Zn(II) and Mn(II)] have been determined in 60% ethanol-water medium ofμ = 0.1M (NaCl) at 25°C. It is observed that the formation constants for chelates with 3d transition metals follow the order
Mn(II) < Co(II) < Ni(II) < Zn(II) < Cu(II). The effects of metal ions, ionic radii, electronegativities and ionization potentials
on chelate formation constants are discussed.
Complexes of UO2(II) and Pd(II) have been synthesized and characterised by elemental analysis, electrolytic conductance, IR spectra and magnetic
measurements. The ligand forms the complexes PdLCl and UO2L2,2H2O, where L is a uninegatively charged tridentate ligand (ONO donor sets). 相似文献
49.
A new rapid precise method for the spectrophotometric microdetermination of group IIIA metal ions with 5-phenylazo-8-quinolinol (I) and 5-(p-chlorophenylazo)-8-quinolinol (II) is given. The optimum conditions favouring the formation of the complexes are reported, as are the compositions of the complexes, their stabilities, and the ranges for obedience to Beer's law. Spectrophotometric titration methods for Al, Ga and In with EDTA in presence of ligand I or II as indicator are also described. 相似文献
50.
Shehata MR Shoukry MM Nasr FM van Eldik R 《Dalton transactions (Cambridge, England : 2003)》2008,(6):779-786
The complex-formation equilibria of [Pd(SMC)(H2O)2]+, where SMC = S-methyl-l-cysteinate, with bio-relevant ligands such as amino acids, peptides, dicarboxylic acids and DNA constituents were studied and their formation constants were determined. The binding mode of the ligands containing various functional groups was studied and the speciation diagrams were evaluated. The kinetics of base hydrolysis of amino acid esters bound to [Pd(SMC)(H2O)2]+ was studied in aqueous solution at 25 degrees C and 0.1 M ionic strength. The effect of solvent polarity and temperature on the hydrolysis of coordinated glycine methyl ester was investigated. The activation parameters are evaluated and discussed. 相似文献