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采用密度泛函方法研究了十二胺在气相、苯、乙酸、乙醇及水中的分子构型、电荷分布以及前线轨道。首先采用B3LYP/6-31G(d,p)及B3 LYP/6-311++G(d,p)进行优化,采用自洽反应理论(SCRF)的极化连续介质模型(PCM)进行不同溶剂条件下的优化并进行自然键轨道(NBO)分析。结果表明,对比气相条件下,十二胺分子的几何构型发生了微弱变化,这种变化随着溶剂介电常数的增加长程稳定性增强,溶剂化效应使前线轨道中HOMO趋于比LUMO更稳定,NBO分析表明溶剂化能主要来源于LP(1)N_(38)→π~*C_(32)-C_(33)。随着溶剂介电常数的增加,十二胺分子采用B3 LYP/6-31+G(d,p)的△E_(HOMO)-E_(LUMO)由气相-0.23773 a.u至水相中-0.25120 a.u,溶剂化能-13.36 kcal/mol,采用B3 LYP/6-311++G(d,p)的△E_(HOMO)-E_(LUMO)由气相-0.22755 a.u至水相中-0.24004 a.u,溶剂化能-13.02 kcal/mol,溶剂化能趋于稳定,表明十二胺分子的溶剂化效应采用B3 LYP/6-31+G(d,p)构型趋于稳定。采用B3LYP/6-31+G(d,p)对十二胺与水分子氢键超分子结构进行了研究,利用分子静电势(MEP)进行氢键及反应活性位分析,结果表明氢键作用是引起十二胺分子结构和性质变化的主要原因。研究结果对十二胺捕收剂在溶剂条件下对矿物的浮选机理认识具有一定的理论意义。
Density functional theory was used to study the molecular configuration, charge distribution and frontier orbitals of dodecylamine in the gas phase, benzene, acetic acid, ethanol and water. Firstly, B3LYP / 6-31G (d, p) and B3 LYP / 6-311 ++ G (d, p) were used for optimization. Different continuous solvents (PCMs) Under the conditions of optimization and the natural bond orbital (NBO) analysis. The results show that under the control of gas phase, the geometry of dodecylamine changes slightly. The long-range stability of dodecylamine increases with the increase of solvent permittivity. The solvation effect makes the HOMO in frontier orbit to be more than that of LUMO Stable NBO analysis showed that solvation energy mainly came from LP (1) N_ (38) → π ~ * C_ (32) -C_ (33). With the increase of the dielectric constant of the solvent, the dodecylamine molecule has the △ E HOMO -E LUMO of B3 LYP / 6-31 + G (d, p) from -0.23773 au in the gas phase to -0.25120 au in the aqueous phase , The solvation energy is -13.36 kcal / mol, the △ E HOMO -E LUMO of B3 LYP / 6-311 ++ G (d, p) is from -0.22755 au in the gas phase to -0.24004 au in the aqueous phase, The solvation energy of the dodecylamine tends to be stable with the energy of -13.02 kcal / mol, indicating that the solvation effect of dodecylamine tends to be stable with B3 LYP / 6-31 + G (d, p) configuration. The supramolecular structure of the hydrogen bond between dodecylamine and water has been studied by B3LYP / 6-31 + G (d, p). Hydrogen bonding and reactive site analysis using molecular electrostatic potential (MEP) showed that hydrogen bonding Is caused by dodecylamine molecular structure and properties of the main reasons for change. The research results have certain theoretical significance for understanding the flotation mechanism of dodecyl amine collector under the condition of solvent.