Department of Chemical and Petroleum Engineering, University of Calgary, Alberta, Canada.
Department of Chemical and Materials Engineering, Concordia University, Montreal, Quebec, Canada.
Sci Rep. 2018 Jan 9;8(1):176. doi: 10.1038/s41598-017-18587-1.
Density functional theory models are used to examine five biodegradable ionic liquids (ILs) each one consisting of a substitutional group (-OH, -NH -COOH, -COOCH, and -OCH) incorporated into the cation of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF]). The results reveal that hydrogen atoms in -NH -COOH, and -COOCH form intramolecular hydrogen bonds with fluorine atoms in [BF], whereas hydrogen atoms in -OH and -OCH do not form hydrogen bonds with [BF]. Further analysis of electron density at bond critical points and noncovalent interactions suggest that [BMIM][BF] with -COOH has stronger intramolecular hydrogen bonds than other ILs. The extraction mechanism for a model naphthenic acid is hydrogen bonding, with F···H being the strongest hydrogen bond and O···H ranking second. More intermolecular hydrogen bonds occur when model naphthenic acid is adsorbed by [BMIM][BF] with -COOH and -COOCH. The interaction energy between model naphthenic acid and ILs with -COOH and -COOCH is higher than that with -OH, -NH, and -OCH.
密度泛函理论模型被用于研究五种可生物降解的离子液体（ILs），它们分别由取代基（-OH、-NH 2 、-COOH、-COOCH 3 和-OCH 3 ）引入到 1-丁基-3-甲基咪唑四氟硼酸盐（[BMIM][BF 4 ]）阳离子中。结果表明，-NH 2 、-COOH 和 -COOCH 3 中的氢原子与 [BF 4 ]中的氟原子形成分子内氢键，而 -OH 和 -OCH 3 中的氢原子则不与 [BF 4 ]形成氢键。对键临界点处电子密度和非共价相互作用的进一步分析表明，带有-COOH 的[BMIM][BF 4 ]具有比其他 ILs 更强的分子内氢键。模型环烷酸的萃取机制是氢键，其中 F···H 是最强的氢键，O···H 排名第二。当模型环烷酸被带有-COOH 和 -COOCH 3 的[BMIM][BF 4 ]吸附时，会发生更多的分子间氢键。模型环烷酸与带有-COOH 和 -COOCH 3 的 ILs 之间的相互作用能高于与 -OH、-NH 2 和 -OCH 3 的相互作用能。
