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采用可极化的连续介质模型(PCM),运用密度泛函理论(DFT),在B3LYP/6-31+G**水平下研究了溶剂极性对有机π共轭配体N,N’-Bis-(3-pyridyl)ethylene-bis-urea(BPEBU)中syn-anti构象的分子几何和电子结构的影响,并借助分子动力学模拟的方法,采用明确溶剂模型研究了溶质-溶剂分子间的相互作用.密度泛函理论计算结果表明,随着溶剂极性的增强,BPEBU中尿素基上的C O键和N—H键以及吡啶环上的C—N键被明显极化,使羰基氧原子和吡啶氮原子的电负性明显增强,尿素基的N—H键上氢原子的正电荷也显著增加.分子动力学模拟统计的结果表明,在极性较强的乙醇溶液中,有明确的O…H—O,N…H—O和N—H…O等3种氢键作用存在,而在丙酮溶液中,只有N…H—O一种氢键作用存在,而且与乙醇溶液中的N…H—O作用相比要弱些.另外,采用密度泛函理论方法结合连续/明确的混合溶剂模型,优化得到了溶质-溶剂三聚体的超分子簇结构,与分子动力学模拟的第一溶剂层中的超分子结构相比,两者定性一致.
Using polarizable continuum model (PCM) and density functional theory (DFT) at B3LYP / 6-31 + G ** level, the effect of solvent polarity on the stability of organic π-conjugated ligands N, N’- The molecular geometry and electronic structure of the syn-anti conformation in Bis- (3-pyridyl) ethylene-bis-urea (BPEBU) were investigated by means of molecular dynamics simulations using a well-defined solvent model The results of density functional theory calculations show that with the increase of solvent polarity, the CO bond and N-H bond on the urea group and the C-N bond on the pyridine ring in BPEBU are obviously polarized, and the carbonyl oxygen atom And pyridine nitrogen atoms significantly increased, the urea N-H bond on the positive charge of hydrogen atoms also increased significantly.Molecular dynamics simulation results show that in the more polar ethanol solution, there is a clear O ... H-O, N ... H-O and N-H ... O exist in the presence of three kinds of hydrogen bonds, but in the acetone solution, only N ... H-O a hydrogen bond exists, and ethanol solution N ... H-O was weaker.In addition, using the density functional theory method combined with the continuous / explicit mixed solvent model, the solute-solvent tri The supramolecular cluster structure of the polymer is qualitatively consistent with the supramolecular structure in the first solvent layer modeled by the molecular dynamics simulation.