3531-14-4Relevant academic research and scientific papers
Quaternary ammonium ions can externally block voltage-gated K+ channels. Establishing a theoretical and experimental model that predicts KDS and the selectivity of K+ over Na+ ions
Wempe
, p. 63 - 78 (2007/10/03)
The physicochemical basis for the high ion selectivity of potassium channels is poorly understood. In the present studies, external blockade of cloned voltage-gated potassium channels with alkyl quaternary ammonium ions are analyzed from a model derived from theory and experimental data. Atomic mass units, electrostatic potential residing on the nitrogen atom, the COSMO van der Waals solvent accessible surface, the Onsager solvation model, and the isodensity PCM solvation model are computed at the semi-empirical and the ab initio levels of theory. A structure-activity relationship (SAR) exists between the calculated values and the experimentally obtained KD (mM). The SAR model gives us KD predictions and when K+ and Na+ are incorporated into the model, it dramatically predicts the selectivity of K+ over Na+ ions.
SIGNIFICANCE TEST OF REFRACTIVE INDEX OF SOLVENT IN EVALUATION OF EFFECT OF MEDIUM ON RATES OF QUATERNIZATION REACTIONS OF METHYL IODIDE WITH AMINES
Nevecna, Tat'jana,Bekarek, Vojtech
, p. 180 - 184 (2007/10/02)
The rate constants have been measured of the reactions of methyl iodide with triethylamine (I) and tributylamine (III) at 293 K in twelve aprotic solvents, methyl iodide with tripropylamine (II) at 293, 313, 323, and 333 K in fifteen solvents differing greatly in their dipole moments, relative permittivities, and refractive indexes, and diiodomethane with tripropylamine in diiodomethane at 293 K (k1 = 2.1 * 10-5 s-1).The aprotic solvents predominantly affect the activation entropy which for the reaction of II varies from -200 J mol-1 s-1 (in cyclohexane) to-108 J mol-1 s-1 (in diiodomethane).The activation enthalpy of the reaction of methyl iodide with tripropylamine (II) is only little affected by aprotic solvents, a significant increase in activation enthalpy has been observed in the case of amphiprotic solvents.The evaluation of effect of medium on the rate constants of the above-mentioned reactions by means of the Kirkwood functions of relative permittivity and refractive index has shown a significant contribution of the refractive index of solvent which is comparable with the effect of relative permittivity.
