2-羟基吡啶与水氢键作用的理论研究

本文采用量子化学的Hatree-Fock方法和密度泛函理论(DFT)的B3LYP方法,在6-31G(d)水平上,研究了2-羟基吡啶分子(Hy)及其酮式互变异构体2(1H)-吡啶酮(Py)与水的相互作用。考察它们之间在形成Hy…H2O,Py…H2O,Hy…Hy,Py…Py和Hy…Py等复合物前后的能量变化和分子结构参数变化特点。计算结果表明,在这些复合物中都形成了较强的氢键作用,在水合物中,Py与水形成复合物时能量降低较多,与实验结果一致。经过零点振动能(ZPVE)和基组叠加误差(BSSE)校正后的复合物离解能分别为38.3,40.8,73.0,82.7和71.1 kJ/mol(B3LYP/6-31G(d)),水合物的离解能远小于二聚体复合物,而酮式结构的二聚体的离解能最大。

Theoretical Study on the Hydrogen Bond Interaction in Tautomers of 2-Hydroxy Pyridine and Water

The Hartree-Fock method and density functional theory (B3LYP method) at the 6-31G(d) basis set level were used to determine the molecular geometrical parameters and hydrogen bonding energies of oxo form (Py) and hydroxy form (Hy) tautomers of 2-hydroxy pyridine, dimers and hydrated complexes. Five complexes, Hy…H2O, Py…H2O, Hy…Hy, Py…Py and Hy…Py, were computed in this study. The DFT and ab initio HF predicted results for Py are in agreement with the available experimental values. The calculations also show that Py become more stable than Hy in water. The dissociation energies mainly due to the stabilization energy associated from the dual hydrogen-bonding formation were calculated as the change in the molecular enthalpy of formation in the conversion of the monomers individually into the dimers or hydrated tautomers. For the dissociation energy, the results indicate that the hydrated tautomers of Hy and Py are smaller than those of their dimers. The dissociation energies predicted at the B3LYP/6-31G(d) level for the five complexes corrected by the basis set superposition error (BSSE) and zero point vibrational energy (ZPVE) are 38.3, 40.8, 73.0, 82.7 and 71.1kJ/mol, respectively.