Theoretical Calculation of the Thermodynamic Properties of 20 Amino Acid Ionic Liquids
Theoretical Calculation of the Thermodynamic Properties of 20 Amino Acid Ionic Liquids
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20种氨基酸离子液体热力学性质的理论计算
DOI：
10.1021/acs.jpcb.8b06813
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发表时间：
2018-11-22
影响因子：
3.3
通讯作者：
Zhang, Wei
中科院分区：
文献类型：
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作者：
Nie, Bingyu;Li, Ruifang;Zhang, Wei
采用从头算、分子动力学模拟、Born-Haber循环分析和等键反应相结合的方法，研究了含20个氨基酸（[AA]（-））和1-乙基-3-甲基咪唑（[AMm]（+））的气相氨基酸离子液体（AAILs）的热力学性质.用M06-2X/TZVP方法研究了[AA]的结构和离解谱，并考虑了色散相互作用，用MP2/Aug-cc-pVTZ方法进行了修正.用分子动力学方法计算了20种AAIL的蒸发焓，用密度泛函理论/M06-2X方法和等键反应方法计算了20种[AA]（-）阴离子和[AA m]（+）阳离子的气相生成焓。为了获得AAIL的Δ H-f，评估相应BH循环中的互连。通过对20个[M] [AA]离子对的系统研究，得到了影响AAILs热力学性质的主要因素，包括烷基链的长度、原子间电子效应、环状基团的空间排斥以及官能团形成的氢键.一般来说，这项工作的结果提供了洞察的结构性质的关系，不仅是离子液体，但也任何离子或分子物质。
The thermodynamic properties of gas-phase amino acid ionic liquids (AAILs) containing 20 amino acids ([AA](-)) and 1-ethyl-3-methylimidazolium ([Emim](+)) are studied using a combination of the ab initio method, molecular dynamics simulations, Born-Haber (BH) cycle analysis, and isodesmic reactions. The M06-2X/TZVP method is used to explore the structure and dissociation enthalpies of [Emim] [AA] by considering dispersion interaction, and the MP2/Aug-cc-pVTZ method is used to correct these enthalpies. The vaporization enthalpies of all 20 AAILs are calculated by molecular dynamics simulations, and the gas-phase formation enthalpies (Delta H-f) of the 20 [AA](-) anions and [Emim](+) cation are calculated by the density functional theory/M06-2X method and isodesmic reaction approaches. To obtain the Delta H-f of the AAILs, interconnections in the corresponding BH cycles are evaluated. A systematic study of the 20 [Emim] [AA] ion pairs provides some initial factors contributing to the thermodynamic properties of AAILs: including length of the alkyl chain, interatomic electronic effects, steric repulsion from the cyclic group, and H-bonds formed by functional groups. Generally speaking, the results of this work provide insights into the structure property relationships of not only ILs but also any ionic or molecular substance.