Metal complexes of cephradine: Synthesis and equilibrium studies

Shoukry, Mohamed M.; Shoukry, Eman M.; El‐Medani, Samir M.

doi:10.1007/bf00811010

Cited by 11 publications

(6 citation statements)

References 23 publications

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“…This means that the decrease of log 10 K NH + values with increasing dioxane content can be interpreted as resulting from non-electrostatic forces, which could include geometrical factors, hydrogen bonding and solute-solvent interactions. This behavior is in agreement with that proposed for oximes [27] and cephradines [28]. (4) The formation constants of trimethyltin(IV) complexes with IDP decrease upon addition of dioxane (Fig.…”

Section: Effect Of Solventsupporting

confidence: 88%

Potentiometric Determination of the Stability Constants of Trimethyltin(IV) Chloride Complexes with Imino-bis(Methylphosphonic Acid) in Water and Dioxane–Water Mixtures

El‐Sherif

2012

J Solution Chem

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The interaction of trimethyltin(IV) (TMT) with imino-bis(methylphosphonic acid) (IDP), abbreviated as H 4 L, was investigated at 25°C and at ionic strength 0.1 mol·dm −3 (NaNO 3 ) using a potentiometric technique. The formation constants of the complexes formed in solution were calculated using the nonlinear least-squares program MINIQUAD-75. The stoichiometry and stability constants are reported for the complexes formed. The results show the formation of 110, 111, 112 and 11-1 complexes for the TMT-IDP system. The concentration distribution of the various complex species was evaluated. The effect of dioxane as a solvent, on both the protonation constants and the formation constants of trimethyltin(IV) complexes with IDP, is discussed. The thermodynamic parameters H • and S • calculated from the temperature dependence of the equilibrium constants were evaluated. The effect of ionic strength on the protonation constants of IDP is also discussed.

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Section: Effect Of Solventsupporting

confidence: 88%

Potentiometric Determination of the Stability Constants of Trimethyltin(IV) Chloride Complexes with Imino-bis(Methylphosphonic Acid) in Water and Dioxane–Water Mixtures

El‐Sherif

2012

J Solution Chem

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“…This is due to the instability of the antibiotics in aqueous media [11]. 1 · 10 −2 M solution of the drug substance was prepared by dissolving the accurate weight in 5 · 10 −2 M aqueous HCl.…”

Section: Introductionmentioning

confidence: 99%

“…A non-linear dependence of the ionization Gibbs energies (∆ diss G • ) on the mole fraction of 1,4-dioxane and the reciprocal of the dielectric constant of the solvent mixtures was observed. The solvatochromic parameters were found to be useful and are widely used in explaining many physicochemical solute properties [6][7][8][9][10].Although ionization constants of HCeph have been determined [11,12], nothing is known of the respective reaction enthalpies and entropies. Both ∆ diss G • and ∆ diss S • were linearly related to ∆ diss H • , given isoequilibrium relationships.…”

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confidence: 99%

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Thermodynamic of Transfer and Preferential Solvation of Antibiotic Cephradine in 1,4-Dioxane-Water Mixtures

Shehatta¹

2001

Zeitschrift Für Physikalische Chemie

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The ionization constants of cephradine in 0, 10, 20, 30, 40, 50, 60, 70, 80 and 90% (v/v) 1,4-dioxane-water mixed solvents were determined using a potentiometric technique and an automatic titrator. The measurements were performed at four different temperatures and 0.1 M KCl, and thus the thermodynamic parameters of ionization and transfer were evaluated. The ionization of cephradine has been found to be endothermic and entropically unfavourable. A non-linear dependence of the ionization Gibbs energies (∆ diss G • ) on the mole fraction of 1,4-dioxane and the reciprocal of the dielectric constant of the solvent mixtures was observed. The variation of the ∆ diss G • values (and thus pK a values) obtained over the whole composition range studied can be explained in terms of preferential solvation of cephradine in 1,4dioxane-water mixtures. Both ∆ diss G • and ∆ diss S • were linearly related to ∆ diss H • , given isoequilibrium relationships. The ∆ diss H • -∆ diss S • susceptibilities are different for the first and second ionization processes as well as for water-rich and 1,4-dioxanerich zones. On the basis of the standard Gibbs energies of hydrogen ion from water to 1,4-dioxane-water mixtures, ∆ trans G • (H + ) and the relative values of ionized and unionized species of cephradine, the effect of solvent on its ionization in 1,4-dioxanewater mixtures is clarified. The ∆ diss G • values are well correlated with the solvent polarity parameter of Dimroth and Reichardt, E T (30). The linear solvation energy relationships method (LSER) was also applied to correlate the thermodynamic parameters with the Kamlet and Taft solvatochromic parameters (α, β, π * ) of 1,4-dioxane-water mixtures. Thus, calculation of the thermodynamic parameters of ionization and transfer in any 1,4-dioxane-water mixtures up to 90% (v/v) can be done using the obtained equations.β-Lactam antibiotics are common and widely used as antibacterial drugs [1,2]. They are broad-spectrum antibiotics due to their ability to inhibit the protein synthesis on the ribosomes [3]. Cephalosporin antibiotics are among the most important class of drugs against infections diseases caused by bacteria [4]. Cephradine (HCeph) is an orally active cephalosporin in clinical practice. pK a values are of vital importance in various chemical and bio-chemical areas. These are essential in understanding the distribution, transport behaviour, binding to receptors, mechanism of action of certain pharmaceutical preparations, dissolution rates, rates of gastrointestinal absorption, incompatibilities, etc. and to interpret structure-activity relationships [5].Aquo-organic mixtures offer a suitable media for biologically interactions because they simultaneously show low polarity and a partially aqueous content that is always present in biological systems. This motivated us to undertake the calculation of the thermodynamic functions of the ionization of HCeph in 1,4-dioxane-water mixtures. These mixtures have been selected in this study owing to the wide range of dielectric const...

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“…Hence, it seems interesting to study the formation equilibrium of Cd(II)-Trien complex and to investigate its interaction with other ligands commonly exist in biological fluids. In continuation of our studies on the binary and ternary complexes of biological significance [13][14][15][16][17], the present paper describes the potentiometric study of the binary and ternary …”

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confidence: 99%

Binary and ternary complexes of Cd(II) involving triethylenetetramine and selected amino acids and DNA units

1998

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Abstract. The formation equilibria of the binary complex of cadmium(II) with triethylenetetramine (Trien) and of ternary complexes Cd(Trien)L, where L refers to amino acids, DNA constituents and related compounds have been investigated. Cd(II) was found to form a highly stable complex with Trien. The acid-base equilibria of Cd(Trien) 2+ were characterized. Ternary complexes of amino acids and DNA constituents are formed through stepwise mechanism, whereby Trien binds to Cd(II), followed by interaction with ligand (L), whereas thiol-containing ligands form ternary complexes through a simultaneous mechanism. The formation constants of the complexes were determined at 25 ~ and # = 0.1M NaNO3. The participation of different ligand functional groups in the complex-formation was examined.Key words: potentiometry, triethylenetetrattfine, Cd(II) complexes, amino acid complexes, DNA complexes, stability constants, ternary complexes.The great majority of the work of biological chemists is concerned with the coordination chemistry of essential metal ions in living organisms, and the examination of aspects of the interactions of these essential metal ions with the rest of the enzymes of the cells in which they are found. The present study, however is concerned with the manipulation of the coordination environment of toxic metal ions in order to accelerate their excretion from the organism.* To whom correspondence should be addressedThe toxicology of cadrnium(II) is often governed by its interaction with an abundance of certain potential ligands in biological systems [1][2][3][4][5]. In animals, Cd(II) accumulates mainly in the liver and kidney, where it is largely bound to thionein, a sulphur-rich protein [6][7][8]. In red blood cells, Cd(II) has been shown to become complexed by glutathione (GSH) and haemoglobin [9]. The goal of chelating agents treatment of metal intoxication is to transform a toxic metal bound to a constituent (usually a protein) of a living organism into a less toxic metal chelate which is readily excreted.In discussing chelating agent design it was reported that stability constant has long been recognized as a key factor in the determination of the ability of the chelating agent to remove the metal from living organism [10,11]. Also chelating agents that bear a charge of -2 or more, such as the antidotes EDTA and 2,3-dimercaptopropanol, are not able to pass through cellular membranes to an appreciable extent. With this in mind and in the course of the search for a new antidote for cadmium, triethylenetetramine (Trien) was electrically neutral and found to form extremely stable complex with Cd(II) ion. Hence, it seems interesting to study the formation equilibrium of Cd(II)-Trien complex and to investigate its interaction with other ligands commonly exist in biological fluids. In continuation of our studies on the binary and ternary complexes of biological significance [13][14][15][16][17], the present paper describes the potentiometric study of the binary and ternary

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Metal complexes of cephradine: Synthesis and equilibrium studies

Cited by 11 publications

References 23 publications

Potentiometric Determination of the Stability Constants of Trimethyltin(IV) Chloride Complexes with Imino-bis(Methylphosphonic Acid) in Water and Dioxane–Water Mixtures

Potentiometric Determination of the Stability Constants of Trimethyltin(IV) Chloride Complexes with Imino-bis(Methylphosphonic Acid) in Water and Dioxane–Water Mixtures

Thermodynamic of Transfer and Preferential Solvation of Antibiotic Cephradine in 1,4-Dioxane-Water Mixtures

Binary and ternary complexes of Cd(II) involving triethylenetetramine and selected amino acids and DNA units

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