离解(化学)
化学
离子键合
电解质
离子
化学物理
分子动力学
二聚体
红外光谱学
硫氰酸盐
星团(航天器)
光谱学
无机化学
物理化学
计算化学
有机化学
物理
量子力学
程序设计语言
计算机科学
电极
作者
Deborin Ghosh,Sushil S. Sakpal,Srijan Chatterjee,Samadhan H. Deshmukh,Hyejin Kwon,Yung Sam Kim,Sayan Bagchi
标识
DOI:10.1021/acs.jpcb.1c08613
摘要
Ionic electrolytes are known to form various complexes which exist in dynamic equilibrium in a low dielectric medium. However, structural characterization of these complexes has always posed a great challenge to the scientific community. An additional challenge is the estimation of the dynamic association-dissociation time scales (lifetime of the complexes), which are key to the fundamental understanding of ion transport. In this work, we have used a combination of infrared absorption spectroscopy, two-dimensional infrared spectroscopy, molecular dynamics simulations, and density functional theory calculations to characterize the various ion complexes formed by the thiocyanate-based ionic electrolytes as a function of different cations in a low dielectric medium. Our results demonstrate that thiocyanate is an excellent vibrational reporter of the heterogeneous ion complexes undergoing association-dissociation dynamics. We find that the ionic electrolytes exist as contact ion pairs, dimers, and clusters in a low dielectric medium. The relative ratios of the various ion complexes are sensitive to the cations. In addition to the interactions between the thiocyanate anion and the countercation, the solute-solvent interactions drive the dynamic equilibrium. We have estimated the association-dissociation dynamics time scales from two-dimensional infrared spectroscopy. The exchange time scale involving the cluster is faster than that between a dimer and an ion pair. Moreover, we find that the dynamic equilibrium between the cluster and another ion complex is correlated to the solvent fluctuations.
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