Solvent Dependence on Conformational Transition, Dipole Moment, and Molecular Geometry of 1,2-Dichloroethane: Insight from Car−Parrinello Molecular Dynamics Calculations

Abstract

We have investigated the molecular geometry and dipole moment distribution for the major conformational states of 1,2-dichloroethane (DCE) in three different solvents under ambient conditions using the Car-Parrinello mixed quantum mechanics/molecular mechanics method. The solvents studied were water, DCE, and chloroform. Within the time scale investigated, we find a conformational equilibrium existing between the gauche and trans forms of DCE in all three solvents. In the chloroform solvent, the conformational transition occurs more frequently than in water solvent and in liquid DCE (i.e., DCE solute in DCE solvent). The population of gauche conformer is more in the case of water solvent, while the trans conformer dominates in chloroform solvent. We report a bimodal nature of the dipole moment distribution for DCE in all three solute-solvents studied, where the peaks are attributed to the trans and gauche conformational states. The dipole moments of both of the conformational states increase with increasing polarity of the solvent. Also, with an increase in solvent polarity, an increase in the C-Cl bond length and magnitude of atomic charges in DCE has been observed. The increase in atomic charges of DCE is almost twice when the solvent is changed from chloroform to water.

Experimental and theoretical study: Determination of dipole moment of synthesized coumarin–triazole derivatives and application as turn off fluorescence sensor: High sensitivity for iron(III) ions

“…To compute theoretical dipole moments within 0.03D of the experimental values, the addition of extensive configuration interaction with a near-HF quality basis is needed which is computationally extensive. Solvent-solute model is also crucial for the calculation of dipole moment [60]. A polar solvent polarizes a solute more efficiently than a nonpolar solvent and hence it results in a larger charge separation which in turn leads to a higher dipole moment [60].…”

“…Solvent-solute model is also crucial for the calculation of dipole moment [60]. A polar solvent polarizes a solute more efficiently than a nonpolar solvent and hence it results in a larger charge separation which in turn leads to a higher dipole moment [60]. The dipole moments of compound 1 and compound 2 are computed at the B3LYP/6-31G(d) level of theory in different environments (various solvents with varying polarities and gas phase) and are shown in Tables 1 and 2.…”

Molecular dynamics simulations of liquid–liquid interfaces in an electric field: The water–1,2-dichloroethane interface

“…force field for the relative populations in the bulk is in much better agreement with the experiments than the rigid-ion force field, while both force fields show similar discrepancies for the vapor phase, albeit in opposite directions. Both force fields suggest an increase in the population of the gauche state when DCE is dissolved in water relative to the bulk liquid, while the QM calculations with implicit solvent performed here and QM/MM calculations 84 instead predict a 10% decrease. On the other hand, the rotational barrier predicted by the rigid-ion force field appears to be three times smaller than the AMOEBA, which is instead consistent with the QM predictions and closer to the experimental estimate by Gwinn and Pitzer.…”

Molecular Dynamics Simulations of Liquid-Liquid Interfaces in an Electric Field: the Water-1,2-Dichloroethane Interface

“…85 The prediction from the AMOEBA polarisable force field for the relative populations in the bulk is in much better agreement with experiment than the rigid-ion force field, while both force fields show similar discrepancies for the vapour phase, albeit in opposite directions. Both force fields suggest a increase in the population of the gauche state when DCE is dissolved in water relative to the bulk liquid, while the QM calculations with implicit solvent performed here and QM/MM calculations 84 instead predict a 10% decrease. On the other hand, the rotational barrier predicted by the rigid-ion force field appears to be three times smaller than the AMOEBA, which is instead consistent with the QM predictions and closer to the experimental estimate by Gwinn and Pitzer.…”