氟代六元氮杂环化合物与水分子弱相互作用的理论研究

在密度泛函M062X/aug-cc-PVTZ水平下计算研究氟代吡啶和氟代二嗪（哒嗪、嘧啶和吡嗪）与水分子之间的lp···π和氢键两种弱相互作用。计算得到的复合物相互作用能(IE)值显示，全氟取代是吡啶形成稳定lp···π复合物的前提条件，这与已有的实验结果吻合。四氟吡啶3种同分异构体与水形成的氢键复合物则比lp···π复合物更稳定。非全氟取代的三氟哒嗪和三氟嘧啶与水分子的lp···π复合物与相应氢键复合物稳定性相当，其IE值接近:3FPa-II-LP?(?19.3 kJ mol?1) vs.?3FPa-II-HB?(?19.7 kJ mol?1)，3FPm-II-LP?(?16.9 kJ mol?1) vs. 3FPm-II-HB?(?16.5 kJ mol?1)。研究表明这些复合物都可能在光谱实验上被检测确认。静电势分析和AIM分析也从分子水平进一步阐释了这些弱相互作用的微观本质。

Theoretical Study of Weak Interaction Between Fluorinated Six-Membered Nitrogen-heterocyclic Compound and Water

Weak interactions between fluorinated six-membered nitro-heterocyclic compounds and water have been studied at M062X/aug-cc-PVTZ level. Our computational study shows that perfluorinated substitution on pyridine is necessary for the existence of lp···π complex. For three tetrafluorinated pyridine isomers, the hydrogen bond complexes are more stable than the corresponding lp···π ones. While for the fluorinated binary nitrogen-heterocycles, the lp···π complexes 3FPa-II-LP and 3FPm-II-LP with IE values of ?19.3 kJ mol?1 and ?16.9 kJ mol?1, respectively, are competitive with their corresponding hydrogen bond ones 3FPa-II-HB (?19.7 kJ mol?1) and 3FPm-II-HB (?16.5 kJ mol?1). This suggests that different from the case of tetrafluorinated pyridine, 3FPa-II-LP and 3FPm-II-LP has the possibility to be investigated by the spectroscopy experiment. Electrostatic potential and AIM analysis explained the microscopic nature of the weak interactions from molecular scope.