Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5373640 | Chemical Physics | 2014 | 4 Pages |
â¢Stability of the antamanide - K+ complex was determined.â¢Quantum mechanical DFT calculations were applied.â¢The structure of the resulting complex was predicted.
On the basis of extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium K+ (aq) + 1·Na+ (nb) â1·K+ (nb) + Na+ (aq) taking part in the two-phase water-nitrobenzene system (1 = antamanide; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log Kex (K+, 1 · Na+) = 0.2 ± 0.1. Further, the stability constant of the 1 · K+ complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log βnb (1 · K+) = 4.7 ± 0.2. Finally, by using quantum mechanical DFT calculations, the most probable structure of the cationic complex species 1 · K+ was derived. In the resulting complex, the “central” cation K+ is bound by four bond interactions to the corresponding four carbonyl oxygen atoms of the parent ligand 1. Besides, the whole 1 · K+ complex structure is stabilized by two intramolecular hydrogen bonds. The interaction energy of the considered 1 · K+ complex was found to be â346.6 kJ/mol, confirming also the formation of this cationic species.
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