Effects of polarizability on the structural and thermodynamics properties of [C{sub n}mim][Gly] ionic liquids (n = 1–4) using EEM/MM molecular dynamic simulations
- Key Laboratory of Green Synthesis and Preparative Chemistry of Advanced Materials, College of Chemistry, Liaoning University, Shenyang 110036 (China)
An extended electronegativity equalization method/molecular mechanics (EEM/MM) model for ionic liquids is used to investigate the structures and properties of 1-alkyl-3-methylimidazolium glycine ionic liquids [C{sub n}mim][Gly] (n = 1–4) with alkyl substituents of different lengths. The EEM/MM model describes the electrostatic interactions of atoms and their changes in different ambient environments. This property is the most outstanding characteristic of the model. EEM parameters (i.e., valence electronegativities and valence hardness parameters) are calibrated using linear regression and least-squares methods, which can accurately predict the gas-phase properties of [C{sub n}mim]{sup +}, [Gly]{sup −}, and [C{sub n}mim][Gly] ion pairs. We utilize the EEM/MM force field to systematically investigate the effects of polarizability on the accuracy of [C{sub n}mim][Gly] properties predicted through the molecular dynamic simulations. EEM/MM explicitly describes the atom-based polarizability of [C{sub n}mim][Gly]; thus, the densities, enthalpies of vaporization, self-diffusion coefficients, and conductivities of the [C{sub n}mim][Gly] are consistent with the experimental values. The calculated radial distribution functions provide a mechanistic understanding of the effects of polarizability on ionic aggregations in amino acid ionic liquids. The effects of alkyl chain length on the diffusion coefficient and conductivity are also discussed.
- OSTI ID:
- 22416121
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 6 Vol. 142; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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