Physik Department, Technische Universität München, Garching, Germany.
Phys Chem Chem Phys. 2012 Dec 14;14(46):15995-6001. doi: 10.1039/c2cp42293j.
Systematic ab initio calculations are combined with a deconvolution of electrostatic contributions to analyze the interplay between potential hydrogen bond acceptors and organic rings with C(sp(2))-H groups (benzene, pyridine and cyclopentadiene). A distinct anisotropic interaction between the ring systems and the electron lone pairs of cyanide, water and other acceptor species is revealed that favors the in-plane orientation of the proton acceptor group. In the attractive regime this interaction carries a pronounced electrostatic signature. By decomposing the electrostatic contribution into parts attributed to different subunits of the ring systems we demonstrate that a major proportion of the interaction energy gain is originating from the non-adjacent moieties, that are not in close contact with. This behavior holds equally for homocyclic, heterocyclic and non-aromatic rings but contrasts that of the ethyne molecule, taken as reference for a weak hydrogen bond donor clearly exhibiting the expected localized character. The ring interaction requires the presence of π-electron clouds and typically results in an interaction energy gain of 40 to 80 meV. Our findings suggest the proton acceptor-ring interaction as a new category of intermolecular non-covalent interactions.
系统从头算结合静电贡献的反卷积分析了潜在氢键受体与具有 C(sp(2))-H 基团的有机环（苯、吡啶和环戊二烯）之间的相互作用。揭示了氰化物、水和其他受体物种的环体系与电子孤对之间明显的各向异性相互作用，有利于质子受体基团的面内取向。在吸引态下，这种相互作用具有明显的静电特征。通过将静电贡献分解为归因于环体系不同亚基的部分，我们证明相互作用能增益的主要部分来自非相邻部分，它们与受体基团没有紧密接触。这种行为对于同环、杂环和非芳香环是等效的，但与乙炔分子的行为相反，乙炔分子作为弱氢键供体的参考，明显表现出预期的局域特征。环相互作用需要π 电子云的存在，通常导致 40 到 80 meV 的相互作用能增益。我们的发现表明质子受体-环相互作用是一种新的分子间非共价相互作用类别。
