Potentiometric and ab initio studies of acid–base interactions of substituted 4-halo(Cl,Br)pyridine N-oxide systems

Gurzyński, Łukasz; Puszko, Aniela; Makowski, Mariusz; Makowska, Joanna; Chmurzyński, Lech

doi:10.1016/j.jct.2006.04.001

Cited by 8 publications

(5 citation statements)

References 42 publications

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“…a N-oxide abbreviations 2,5Me 2 4ClPyO-2,5-dimethyl-4-chloropyridine N-oxide; 2,5Me 2 4BrPyO-2,5-dimethyl-4-bromopyridine N-oxide; 3,5Me 2 4ClPyO-3,5-dimethyl-4-chloropyridine N-oxide; 3,5Me 2 4BrPyO-3,5-dimethyl-4-bromopyridine N-oxide; 2,3,6Me 3 4ClPyO-2,3,6-trimethyl-4-chloropyridine N-oxide; 2,3,6Me 3 4BrPyO-2,3,6-trimethyl-4-bromopyridine N-oxide. b Data from reference [32]. hydrogen bond bridges OÁ Á ÁHÁ Á ÁO in polar non-aqueous solvents.…”

Section: Discussionmentioning

confidence: 99%

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Experimental and theoretical studies of solvent effects on the hydrogen bonds in homoconjugated cations of substituted 4-halo (Cl, Br) pyridine N-oxide derivatives

Gurzyński

Puszko

Makowski

et al. 2007

The Journal of Chemical Thermodynamics

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Hydrogen bond OHO-type bridges formed between six substituted 4-halo (Cl, Br) pyridine N-oxide systems and their simple cations have been investigated by using the potentiometric titration method. The formation constants of these complexes (expressed as lg K BHB þ ) have been determined in two non-aqueous aprotic solvents with different polarity, i.e., acetone (AC) and acetonitrile (AN). It has been observed that tri-and tetra-substituted pyridine N-oxides [B] and their cationic acids [BH + ] form stable homocomplexed cations [BHB + ] stabilized by OÁ Á ÁHÁ Á ÁO bridges in both solvents used. It has been found that the most stable homocomplexed system is formed by 3,5-dimethyl-4-chloropyridine N-oxide (3,5Me 2 4ClPyO). The lg K BHB þ values for this compound in acetone and acetonitrile are 3.15 and 2.82, respectively. Furthermore, by using ab initio methods at the RHF and MP2 levels utilizing the Gaussian 6-31++G ** basis set, the energies of formation of the homocomplexed cations and Gibbs free energies have been determined in vacuo. The calculated energy parameters in vacuo have been compared with the cationic homoconjugation constants determined potentiometrically in acetone and acetonitrile to establish a correlation between these magnitudes. Additionally, the results of potentiometric measurements have been used to determine the acidity constants of the conjugate acids of N-oxides.

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Section: Discussionmentioning

confidence: 99%

“…Thus, this method can be applied to systems of any degree of complexity [28][29][30]. The details of the calculations of equilibrium constants have been described previously [32].…”

Section: Calculationsmentioning

confidence: 99%

Experimental and theoretical studies of solvent effects on the hydrogen bonds in homoconjugated cations of substituted 4-halo (Cl, Br) pyridine N-oxide derivatives

Gurzyński

Puszko

Makowski

et al. 2007

The Journal of Chemical Thermodynamics

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“…This method takes into account not only errors in the e.m.f., but also those in titration volume, stock-solution preparation, electrode calibration parameters, and reagent impurities, in addition to the equilibrium constants determined from other measurements [20]. The details of the calculations of equilibrium constants have been described previously [21,22].…”

Section: Determination Of Pk Values By Using Potentiometrymentioning

confidence: 99%

Determination of dissociation constants for coordination compounds of Cr(III) and Co(III) using potentiometric and spectrophotometric methods

Chylewska

Jacewicz

Zarzeczańska

et al. 2008

The Journal of Chemical Thermodynamics

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“…Hydrogen-bond and salt-bridge formation between natural amino-acid side chains was investigated in our previous work. − On the basis of molecular dynamics simulation data, the potential of mean force (PMF) surfaces were calculated and analyzed for like-charged and oppositely charged side chains. We showed that the most significant are the interactions between oppositely charged amino-acid side chains. − The stabilizing electrostatic free energy of the salt bridges arises from the attraction between opposite charges.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Studies of Interactions between O-Phosphorylated and Standard Amino-Acid Side-Chain Models in Water

et al. 2015

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Phosphorylation is a common post-translational modification of the amino-acid side chains (serine, tyrosine, and threonine) that contain hydroxyl groups. The transfer of the negatively charged phosphate group from an ATP molecule to such amino-acid side chains leads to changes in the local conformations of proteins and the pattern of interactions with other amino-acid side-chains. A convenient characteristic of the side chain–side chain interactions in the context of an aqueous environment is the potential of mean force (PMF) in water. A series of umbrella-sampling molecular dynamic (MD) simulations with the AMBER force field were carried out for pairs of O-phosphorylated serine (pSer), threonine (pThr), and tyrosine, (pTyr) with natural amino acids in a TIP3P water model as a solvent at 298 K. The weighted-histogram analysis method was used to calculate the four-dimensional potentials of mean force. The results demonstrate that the positions and depths of the contact minima and the positions and heights of the desolvation maxima, including their dependence on the relative orientation depend on the character of the interacting pairs. More distinct minima are observed for oppositely charged pairs such as, e.g., O-phosphorylated side-chains and positively charged ones, such as the side-chains of lysine and arginine.

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Potentiometric and ab initio studies of acid–base interactions of substituted 4-halo(Cl,Br)pyridine N-oxide systems

Cited by 8 publications

References 42 publications

Experimental and theoretical studies of solvent effects on the hydrogen bonds in homoconjugated cations of substituted 4-halo (Cl, Br) pyridine N-oxide derivatives

Experimental and theoretical studies of solvent effects on the hydrogen bonds in homoconjugated cations of substituted 4-halo (Cl, Br) pyridine N-oxide derivatives

Determination of dissociation constants for coordination compounds of Cr(III) and Co(III) using potentiometric and spectrophotometric methods

Theoretical Studies of Interactions between O-Phosphorylated and Standard Amino-Acid Side-Chain Models in Water

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