咪唑基离子液体与小分子相互作用的理论研究

采用密度泛函理论考察了1-乙基-3-甲基咪唑四氟合硼酸盐（EMIM]BF4]）和2-甲基噻吩（2-MT）、正己烷（HEX）、异丁基硫醇（IBT）的相互作用。采用GGA/PW91和DNP基组优化了结构,并用NBO和AIM分析了EMIM]BF4]和2-甲基噻吩（2-MT）、正己烷（HEX）、异丁基硫醇（IBT）的氢键相互作用。EMIM]BF4]离子对最稳定的气相结构表明,BF4]-阴离子的F原子和咪唑环上C2-H2的氢键作用在形成离子对中起重要作用。BF4]-阴离子和EMIM]＋阳离子支链发生氢键作用。BF4]-阴离子趋向于C2-H2形成氢键,这说明,2-甲基噻吩（2-MT）、正己烷（HEX）、异丁基硫醇（IBT）吸附在EMIM]BF4]上没有改变离子液体离子对的主要作用。EMIM]BF4]和2-甲基噻吩发生π···C-H和氢键作用,而EMIM]BF4]和正己烷（HEX）、异丁基硫醇（IBT）主要发生氢键作用。相互作用能表明,2-甲基噻吩优先吸附在离子液体上。

THEORETICAL STUDY ON INTERACTION BETWEEN IMIDAZOLYL IONIC LIQUIDS AND SMALL MOLECULES

Density functional theory has been employed to investigate the interaction between 2-methyl-thiophene （2-MT）,hexane（HEX）,isobutylthiol（IBT）and 1-ethyl-3-methylimidazolium tetrafluoroborate（EMIM]BF4]）. GGA/PW91 functionals and DNP basis set were used to optimize the geometries,and the hydrogen bond interaction betweenEMIM]BF4]and 2-methyl-thiophene（2-MT）,hexane（HEX）,isobutylthiol（IBT）have been analyzed by NBO and AIM methods.The most stable gas-phase structure ofEMIM]BF4]ion pair indicates that hydrogen bond interaction between the fluorine atoms onBF4] - anions and the C2-hydrogen on the imidazole ring plays an important role in the formation of ion pair.Additional interaction is observed betweenBF4] - anion and the hydrogen atoms on the adjacent alkyl side chains ofEMIM] ＋ cation.TheBF4] - anion tends to C2-H2 forming hydrogen bond,suggesting that 2-methyl-thiophene（2-MT）,hexane（HEX）,isobutylthiol（IBT）’s adsorption onEMIM]BF4]do not change the dominant role of ionic liquids pair.The π···C-H interaction and hydrogen bonding interaction occur betweenEMIM]BF4]and 2-methyl-thiophene.The hydrogen bonding interaction exists betweenEMIM]BF4]and hexane,isobutylthiol.The interaction energy suggests that 2-methyl-thiophene is prior to adsorpt on ionic liquids.