Ion Solvation in Polarizable Chloroform:  A Molecular Dynamics Study

Abstract

The structural, thermodynamic, and dynamical properties of the alkali-metal cations and the halide anions in liquid chloroform are investigated using molecular dynamics simulation techniques. From the atomic radial distribution analysis, the chloroform molecules are found to form well-defined solvation shells around the alkali-metal cations and the halide anions. The size of the solvation cage and the coordination number both increase with increasing ion size. In liquid chloroform, all these ions are shown to induce a strong orientational order in the surrounding chloroform molecules as evidenced by the angular distribution functions. We found that the mean electric potentials induced by the chloroform molecules shifted to smaller magnitudes with increasing ion size. Because of the greater electric polarizabilities of the larger ions, the average induced dipole moments were enhanced with increasing ion size. The diffusion coefficients of the alkali-metal cations and the halide anions in liquid chloroform are estimated from the mean-square displacements and the velocity autocorrelation functions. Generally, the diffusion constants of the cations are larger than those of the anions. For the cations, the diffusion constants are of similar magnitudes and do not depend on the ion size. However, the diffusion coefficients of the halide anions show a strong dependence on the ion size. The motion of the first coordination shell chloroform molecules is examined via their velocity autocorrelation functions. These correlation functions behave very similarly, suggesting that the motion of the first solvation shell is not governed by the sizes or the charges of these ions. In addition, the residence time autocorrelation functions of the first solvation shell are evaluated. As expected, the residence time decreases as the ion size increases.

Interfacial Behavior of Ionophoric Systems: Molecular Dynamics Studies on 18-Crown-6 and Its Complexes at the Water-Chloroform Interface

“…22,78 Non-additivity and polarization effects may also modulate the results obtained by standard pairwise additive potentials. 13,16 Despite all these limitations, the results presented here and previously are quite encouraging and in overall agreement with related macroscopic data. We hope that they contribute to develop deeper views on solution and interfacial phenomena, and to stimulate further experiments.…”

“…[17][18][19][20][21]56 Our calculations on 18C6 are consistent with these data. However, the picture of the (18C6) 10 aggregate differs from that of (TBP) 10 21 or of (TPTZ) 16 (Fig. 12) we simulated in comparable conditions.…”

The Unique Molecular Behavior of Water at the Chloroform—Water Interface

“…2 The properties that make the chloroform-water interface effective and important in extraction also make it important for understanding the fundamental interactions present between two largely immiscible liquids and how these interactions affect the interfacial properties, including transport of molecules and ions across the interface. An increasing number of theoretical [3][4][5][6][7][8][9][10][11][12] and experimental [13][14][15][16][17][18][19][20][21][22] studies have emerged in recent years that seek to understand the properties and structuring of water near a hydrophobic surface on a molecular level. However, very few theoretical and even fewer experimental studies have explored how the behavior of water and the interfacial properties change as the polarity of the hydrophobic phase is progressively increased, which is important in achieving a more comprehensive understanding of organic-water interfacial properties.…”

“…33 These MD simulations build on the knowledge base and experience of MD simulations by Benjamin 3,4,11 as well as Chang and Dang, [7][8][9][10] and VSF spectral calculations for water by Morita and Hynes. 34 Population densities and orientations of different types of water-bonded species at the interface are calculated in good agreement with previously published MD results 3,4,[7][8][9][10][11]35,36 and are then used in the calculation of a VSF spectrum for comparison with experiment. 33,37 Information complementary to the experimental results can be extracted from the MD simulations including the types of water-bonded species that contribute to different regions of the VSF spectrum, the interfacial depths of these species, and their orientations.…”

Στατιστική μηχανική μελέτη μέσω μοριακών δυναμικών προσομοιώσεων υγρών μοριακών συστημάτων πρωτικών (MeOH,H_2) και απρωτικών (DMSO, DMF) διαλυτών.

“…Τα αποτελέσματα παρατίθενται στον Πίνακα 9.5. [179][180][181][182][183][184]. Επίσης ένας αρκετά σημαντικός αριθμός εργασιών ασχολείται με την έρευνα διαφό ρων στοιχείων κατά τη διάλυση ιοντικών ενώσεων στη μεθανόλη, που ανήκει και αυτή στην κατηγο ρία των πρωτικών διαλυτών [180,[191][192][193][194][195][196].…”