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Krzysztof Pralat

Bio: Krzysztof Pralat is an academic researcher. The author has contributed to research in topics: Amide & Hydrogen bond. The author has an hindex of 3, co-authored 4 publications receiving 66 citations.

Papers
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TL;DR: In this article, the proprietes de l'aza-2 cyclotridecanone en solution dans CCl 4 were surveyed, mesure de la polarisation dielectrique statique et de l'seffet dielectric non lineaire, determination des 2 constantes d'equilibre d'auto-association, and comparaison avec celles obtenues en spectrometrie IR
Abstract: Etude des proprietes dielectriques de l'aza-2 cyclotridecanone en solution dans CCl 4 -, mesure de la polarisation dielectrique statique et de l'effet dielectrique non lineaire, determination des 2 constantes d'equilibre d'autoassociation, et comparaison avec celles obtenues en spectrometrie IR

10 citations

Journal ArticleDOI
TL;DR: In this paper, the proprietes de l'aza-2 cyclotridecanone en solution dans CCl 4 were surveyed, mesure de la polarisation dielectrique statique et de l'seffet dielectric non lineaire, determination des 2 constantes d'equilibre d'auto-association, and comparaison avec celles obtenues en spectrometrie IR
Abstract: Etude des proprietes dielectriques de l'aza-2 cyclotridecanone en solution dans CCl 4 -, mesure de la polarisation dielectrique statique et de l'effet dielectrique non lineaire, determination des 2 constantes d'equilibre d'autoassociation, et comparaison avec celles obtenues en spectrometrie IR

Cited by
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Journal ArticleDOI
TL;DR: It is found that the two solvated isomers can be clearly distinguished by their infrared spectral profile in the 1000-2000 cm(-)(1) range.
Abstract: The density functional theory based molecular dynamics simulation method (“Car−Parrinello”) was applied in a numerical study of the electronic properties, hydrogen bonding, and infrared spectroscopy of the trans and cis isomer of N-methylacetamide in aqueous solution. A detailed analysis of the electronic structure of the solvated molecules, in terms of localized Wannier functions and Born atomic charges, is presented. Two schemes for the computation of the solute infrared absorption spectrum are investigated: In the first method the spectrum is determined by Fourier transforming the time correlation function of the solute dipole as determined from the Wannier function analysis. The second method uses instead the molecular current−current correlation function computed from the Born charges and atomic velocities. The resulting spectral properties of trans- and cis-NMA are carefully compared to each other and to experimental results. We find that the two solvated isomers can be clearly distinguished by the...

142 citations

Journal ArticleDOI
TL;DR: A combined NMR and dynamic light scattering study on the size of supramolecular structures formed by disodium guanosine 5'-monophosphate, Na(2)(5'-GMP), at pH 8.5 suggests a common stacking mechanism for monomers and G-quartets.
Abstract: We report a combined NMR and dynamic light scattering (DLS) study on the size of supramolecular structures formed by disodium guanosine 5‘-monophosphate, Na2(5‘-GMP), at pH 8. In general, two distinct types of aggregate species are present in an aqueous solution of Na2(5‘-GMP). One type consists of stacking 5‘-GMP monomers, and the other contains stacking G-quartets. Both types of aggregates can be modeled as rodlike cylinders. The cylinder diameter is 10 and 26 A for monomer aggregates and quartet aggregates, respectively. For Na2(5‘-GMP) concentrations between 18 and 34 wt %, the cylinders formed by stacking G-quartets have an average length between 8 and 30 nm, corresponding to a stack of ∼24−87 G-quartets. These nanoscale aggregates are significantly larger than what had previously been believed for Na2(5‘-GMP) self-association at pH 8. The length of both types of 5‘-GMP aggregates was found to increase with Na2(5‘-GMP) concentration but was insensitive to the added NaCl in solution. While the aggrega...

128 citations

Journal ArticleDOI
TL;DR: Absolute free energies of hydration (ΔGhyd) have been computed for 25 diverse organic molecules using partial atomic charges derived from AM1 and PM3 wave functions via the CM1 and CM3 procedures of Cramer, Truhlar, and coworkers.
Abstract: Absolute free energies of hydration (ΔG h y d ) have been computed for 25 diverse organic molecules using partial atomic charges derived from AM1 and PM3 wave functions via the CMI and CM3 procedures of Cramer, Truhlar, and coworkers. Comparisons are made with results using charges fit to the electrostatic potential surface (EPS) from ah initio 6-31G* wave functions and from the OPLS-AA force field. OPLS Lennard-Jones parameters for the organic molecules were used together with the TIP4P water model in Monte Carlo simulations with free energy perturbation theory. Absolute free energies of hydration were computed for OPLS united-atom and all-atom methane by annihilating the solutes in water and in the gas phase, and absolute ΔG h y d values for all other molecules were computed via transformation to one of these references. Optimal charge scaling factors were determined by minimizing the unsigned average error between experimental and calculated hydration free energies. The PM3-based charge models do not lead to lower average errors than obtained with the EPS charges for the subset of 13 molecules in the original study. However, improvement is obtained by scaling the CMIA partial charges by 1.14 and the CM3A charges by 1.15, which leads to average errors of 1.0 and 1.1 kcal/mol for the full set of 25 molecules. The scaled CMIA charges also yield the best results for the hydration of amides including the E/Z free-energy difference for N-methylacetamide in water.

125 citations

Journal ArticleDOI
TL;DR: The cation-enhanced formation of hydrophobic domains in aqueous humic acids has been shown to be a slow process consistent with the evolution and disintegration of humic acid configurations over time.
Abstract: The cation-enhanced formation of hydrophobic domains in aqueous humic acids has been shown to be a slow process, consistent with the evolution and disintegration of humic acid configurations over p...

123 citations

Journal ArticleDOI
TL;DR: In this paper, a polarizable intermolecular potential function (PIPF) was developed for simulation of liquid amides, which includes a pairwise additive component, consisting of the familiar Lenna...
Abstract: We have developed a polarizable intermolecular potential function (PIPF) for simulation of liquid amides. The PIPF potential includes a pairwise additive component, consisting of the familiar Lenna...

105 citations