| | 1 | Author
| G. Anderegg | Requires cookie* | | | Title
| Komplexone, XLVII Die Thermodynamik der Komplexbildung von einigen ein-und zweiwertigen Metallionen mit Aethylendiamintetraacetat-und Uramildiacetat-Ion Complexone, XLVII Thermodynamics of Complex Formation of Some Univalent and Bivalent Metal Ions with Ethylenediaminetetraacetate and Uramildiacetate Anions  | | | | Abstract
| The enthalpies of complex formation of EDTA and uramildiacetate (UDA) with univalent cations (H+, Li+, Na+, K + , Ag+ and T1+) have been obtained by direct calori-metric measurements at ionic strength 0.1 (or 1) and 20 °C. For comparison data for the formation of 1:1 UDA complexes with Mg 2+ , Ca 2+ , Ba 2+ and Sr 2+ have also been obtained. From these values and the stability constants the thermodynamic functions A G and A S are calculated. The results are compared with those of similar systems. | | | |
Reference
| (Z. Naturforsch. 31b, 786—789 [1976]; eingegangen am 15. März 1976) | | | |
Published
| 1976 | | | |
Keywords
| EDTA Complexes, Uramildiacetate Complexes, Stability Constants, Enthalpy, Entropy | | | |
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| default:Reihe_B/31/ZNB-1976-31b-0786.pdf | | | | Identifier
| ZNB-1976-31b-0786 | | | | Volume
| 31 | |
| 2 | Author
| B. S. Sekhon, S. L. Chopra | Requires cookie* | | | Title
| Stabilities of Vanadyl Complexes with Methionine, Phenylalanine, and Threonine | | | | Abstract
| Stepwise formation constants corresponding to 1:1 vanadyl complexes with methionine, phenyl alanine and threonine have been determined at 25 °C, and at various ionic concentrations, viz. 0.01, 0.1 and 0.3 M , maintained by the addition of potassium chloride solution. Thermodynamic stability constants have been obtained by extrapolation of log K values to zero ionic strength. Logarithms of the overall stability constants (lo g £ (u = 0)) are 7.72 for methionine, 7.70 for phenyl alanine and 7.44 for threonine complexes. The corresponding free energy changes (AG°) are — 10.53, — 10.51, — 10.15 kcal-mol-1 respectively. | | | |
Reference
| (Z. Naturforsch. 29c, 336 [1974]; received November 30 1973/April 9 1974) | | | |
Published
| 1974 | | | |
Keywords
| Amino Acid Complexes, Vanadyl Complexes, Stability Constant | | | |
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| default:Reihe_C/29/ZNC-1974-29c-0336.pdf | | | | Identifier
| ZNC-1974-29c-0336 | | | | Volume
| 29 | |
| 4 | Author
| Guogang Liang, NicolasA. Corfù, Helmut Sigel | Requires cookie* | | | Title
| Influence of Decreasing Solvent Polarity (Dioxane-Water Mixtures) on the Stability of Metal Ion Complexes Formed with Phosphate Monoesters | | | | Abstract
| The acidity constants o f H (R —M P)~, where R —M P: = 4-nitrophenyl phosphate (N PhP2). phenyl phosphate (PhP2) and D -ribose 5'-m onophosphate (R ibM P2). and the stability constants of the binary C u (R -M P) com plexes w'ere determ ined by potentiom etric pH titrations in aqueous solution and in 20. 30, 40 and 50% (v/v) dioxane-water mixtures. The solvent influence on the corresponding equilibrium constants is com pared with the same influence on previously studied systems containing uridine 5'-triphosphate. formate or acetate. The influence o f the solvent com position on the various ligand (L) system s was evaluated by constructing log Km(L) versus pK[j(L) plots; in all cases straight lines are obtained with slopes close to 1. This indicates that in all these system s, despite the different negative charges o f the involved ligands, the solvent effect on proton binding and on metal ion binding is approxim ately o f the same size: A decreasing solvent polarity resulting from the addition o f increasing am ounts o f organic solvent to the aqueous solutions favors the affinity o f the negatively charged ligands for protons and metal ions as well. Information o f this type is considered important because the 'effective' or 'equivalent solution' dielectric constants in active-site cavities o f enzym es are reduced com pared with the dielectric constant o f bulk water; i. e., in protein cavities also a decreased 'solvent polarity' is occurring and this is expected to affect the stability o f metal ion-ligand bonds. | | | |
Reference
| Z. Naturforsch. 44b, 538 (1989); received N ovem ber 28 1988 | | | |
Published
| 1989 | | | |
Keywords
| Phosphate M onoester, Metal Ion C om plexes, Solvent Influence, Stability Constants, A ctive-Site Cavities o f Enzymes | | | |
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| default:Reihe_B/44/ZNB-1989-44b-0538.pdf | | | | Identifier
| ZNB-1989-44b-0538 | | | | Volume
| 44 | |
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