二苯并噻吩及其氧化物与离子液体相互作用的理论研究

采用密度泛函理论方法比较了DBT/DBTO₂和[BMIM]⁺[PF₆]^-/[BMIM]⁺[BF₄]^-的相互作用。对最稳定的[BMIM]⁺[PF₆]^-、[BMIM]⁺[PF₆]^--DBT、[BMIM]⁺[PF₆]^--DBTO₂、[BMIM]⁺[BF₄]^-、[BMIM]⁺[BF₄]^--DBT、[BMIM]⁺[BF₄]^--DBTO₂进行了NBO和AIM分析。结果表明,DBT和[BMIM]⁺[PF₆]^-/[BMIM]⁺[BF₄]^-中的咪唑环彼此相互平行,NBO和AIM分析表明它们之间发生了π-π相互作用。H1'和H9'形成的F…H氢键有利于π-π堆积作用的形成。DBTO₂倾向于趋近C2-H2和甲基基团形成O…H相互作用;DBTO₂优先吸附在[BMIM]⁺[PF₆]^-/[BMIM]⁺[BF₄]^-。在模拟油中,[BMIM]⁺[PF₆]^-和[BMIM]⁺[BF₄]^-离子液体对DBTO₂的萃取能力大于DBT,其原因是可能是DBTO₂具有较大的极性和O…H与F…H的氢键作用。

Theoretical study on the interactions between dibenzothiophene/dibenzothiophene sulfone and ionic liquids

The interactions between sulfur-containing compounds of dibenzothiophene (DBT) and dibenzothiophene sulfone (DBTO₂) and ionic liquids of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]⁺[PF₆]^-) and 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]⁺[BF₄]^-) were comparatively studied by using density functional theory. The most stable structures of [BMIM]⁺[PF₆]^-, [BMIM]⁺[PF₆]^--DBT, [BMIM]⁺[PF₆]^--DBTO₂, [BMIM]⁺[BF₄]^-, [BMIM]⁺[BF₄]^--DBT, and [BMIM]⁺[BF₄]^--DBTO₂ systems were obtained by natural bond orbitals (NBO) and atoms in molecules (AIM) analyses. The results indicated that DBT and [BMIM] rings of [BMIM]⁺[PF₆]^-/[BMIM]⁺[BF₄]^- are parallel to each other. There is a strong π-π interaction between them in terms of NBO and AIM analyses. The H1' and H9' involved F…H hydrogen bonding interactions may favor the formation of π-π stacking interactions. The DBTO₂ preferentially locates near the C2-H2 and methyl group of [BMIM]⁺ to form O…H interactions. The predicted geometries and interaction energies imply the preferential adsorption of DBTO₂ on [BMIM]⁺[PF₆]^-/[BMIM]⁺[BF₄]^-. The [BMIM]⁺[PF₆]^-/[BF₄]^- have better extracting ability to remove DBTO₂ than DBT, possibly due to the larger polarity of DBTO₂ and stronger interactions between [BMIM]⁺[PF₆]^-/[BF₄]^- and DBTO₂.