Department of Chemistry, Indian Institute of Technology, Kanpur, Uttar Pradesh, India.
J Comput Chem. 2011 Sep;32(12):2679-89. doi: 10.1002/jcc.21849. Epub 2011 Jun 9.
Molecular dynamics simulations of charged and neutral solutes in dimethyl sulfoxide (DMSO)-chloroform mixtures reveal pronounced nonideality in the solute diffusion with changes of composition of the mixtures. The diffusion coefficient of the anionic solute first decreases, passes through a minimum at DMSO mole fraction of about 0.50, and then increases to reach its value for pure DMSO. The diffusion coefficients of the cationic and neutral solutes are found to decrease with increase in DMSO content of the solvent mixture. The extent of nonideality in the diffusion and orientational relaxation of solvent molecules is found to be somewhat stronger than that in diffusion of the anionic solute in these mixtures. We have also calculated the relaxation of hydrogen bonds formed between DMSO and chloroform molecules. The lifetimes of DMSO-chloroform hydrogen bonds are found to increase monotonically with increase in DMSO concentration. The average number of hydrogen bonds and their average energies are also computed. It is found that an increase in DMSO concentration causes a decrease in the number of DMSO-chloroform hydrogen bonds per DMSO or chloroform molecules but increases the strength of these hydrogen bonds.
在二甲亚砜（DMSO）-氯仿混合物中，带电和中性溶质的分子动力学模拟揭示了组成变化时溶质扩散的显著非理想性。阴离子溶质的扩散系数先减小，在 DMSO 摩尔分数约为 0.50 时通过最小值，然后增加到达到纯 DMSO 的值。阳离子和中性溶质的扩散系数随着溶剂混合物中 DMSO 含量的增加而减小。发现溶剂分子的扩散和取向弛豫中的非理想程度比这些混合物中阴离子溶质的扩散要强一些。我们还计算了 DMSO 和氯仿分子之间形成的氢键的弛豫。发现 DMSO-氯仿氢键的寿命随 DMSO 浓度的增加单调增加。还计算了氢键的平均数量及其平均能量。发现 DMSO 浓度的增加会导致每 DMSO 或氯仿分子的 DMSO-氯仿氢键数量减少，但会增加这些氢键的强度。
