Laboratorio de Estructura Molecular y Propiedades, Area de Química Física, Departamento de Química, Facultad de Ciencias Exactas y Naturales y Agrimensura, Universidad Nacional del Nordeste, Avenida Libertad 5460, (3400) Corrientes, Argentina.
J Phys Chem A. 2010 Mar 4;114(8):2855-63. doi: 10.1021/jp906372t.
In this work, the cooperative effects implicated in bifunctional hydrogen bonds (H-bonds) were studied (in monohydrated six-membered cycloether) within the framework of the atoms in molecules (AIM) theory and of the natural bond orbitals (NBO) analysis. The study was carried out in complexes formed by six-membered cycloether compounds (tetrahydropyrane, 1,4-dioxane, and 1,3-dioxane) and a water molecule. These compounds were used as model systems instead of more complicated molecules of biological importance. All the results were obtained at the second-order Møller-Plesset (MP2) level theory using a 6-311++G(d,p) basis set. Attention was focused on the indicators of the cooperative effects that arise when a water molecule interacts simultaneously with a polar and a nonpolar portion of a six-membered cycloether (via bifunctional hydrogen bonds) and compared with conventional H-bonds where the water molecule only interacts with the polar portion of the cycloether. Different indicators of H-bonds strength, such as structural and spectroscopic data, electron charge density, population analysis, hyperconjugation energy and charge transference, consistently showed significant cooperative effects in bifunctional H-bonds. From the AIM, as well as from the NBO analysis, the obtained results allowed us to state that in the monohydrated six-membered cycloether, where the water molecule plays a dual role, as proton acceptor and proton donor, a mutual reinforcement of the two interactions occurs. Because of this feature, the complexes engaged by bifunctional hydrogen bonds are more stabilized than the complexes linked by conventional hydrogen bonds.
在这项工作中，我们研究了在分子轨道（AIM）理论和自然键轨道（NBO）分析框架内涉及双功能氢键（H 键）的协同效应。该研究是在由六元环醚化合物（四氢呋喃、1,4-二恶烷和 1,3-二恶烷）和一个水分子形成的配合物中进行的。这些化合物被用作模型系统，而不是更复杂的具有生物学重要性的分子。所有结果均在二阶 Møller-Plesset（MP2）水平理论上使用 6-311++G(d,p)基组获得。我们关注的是当水分子同时与六元环醚的极性和非极性部分（通过双功能氢键）相互作用时出现的协同效应的指标，并将其与水分子仅与环醚的极性部分相互作用的传统氢键进行了比较。氢键强度的不同指标，如结构和光谱数据、电子电荷密度、布居分析、超共轭能和电荷转移，一致表明双功能氢键具有显著的协同效应。从 AIM 以及 NBO 分析中，我们获得的结果表明，在水分子同时扮演质子受体和质子供体双重角色的单水合六元环醚中，两个相互作用相互增强。由于这一特性，由双功能氢键形成的配合物比由传统氢键形成的配合物更稳定。
