Dipartimento di Chimica G. Ciamician, via Selmi, 2, 40126 Bologna, Italy.
Phys Chem Chem Phys. 2011 Aug 21;13(31):13901-11. doi: 10.1039/c1cp20824a. Epub 2011 Jun 23.
Recently reported rotational spectroscopic studies on small dimers and oligomers bound by weak hydrogen bonds show that the driving forces, the spatial arrangement and the dynamical features displayed are very different from those involved in stronger and conventional hydrogen bonds. The very small binding energies (similar to those of van der Waals interactions) imply that the stabilization of the dimer is often obtained by networks of weak hydrogen bonds. Even in the presence of multiple bonds the partner molecules show a high degree of internal freedom within the complex. This paper analyses several examples of molecular adducts bound by weak hydrogen bonds formed in free jet expansions and recently characterized by rotational spectroscopy. They include weakly bound complexes of weak donors with strong acceptors (C-H···O,N, S-H···O,N), strong donors (O-H, N-H) with weak acceptors such as the halogen atoms and π systems but also the elusive interactions between weak donors and weak acceptors (C-H···π and C-H···halogen). Examples are also given where rotational spectroscopy highlights that weak hydrogen bonds are extremely important in chiral recognition phenomena and as driving forces of the conformational landscape of important biomolecules.
最近报道的关于通过弱氢键结合的小分子二聚体和低聚物的旋转光谱研究表明，所涉及的驱动力、空间排列和动态特征与强氢键和传统氢键有很大的不同。非常小的结合能（类似于范德华相互作用）意味着二聚体的稳定通常是通过弱氢键网络获得的。即使存在多重键，配合物分子在复合物中也表现出高度的内部自由度。本文分析了在自由射流膨胀中形成的、最近通过旋转光谱表征的几种弱氢键结合的分子加合物的例子。它们包括弱供体与强受体（C-H···O、N、S-H···O、N）之间形成的弱结合复合物、强供体（O-H、N-H）与弱受体（卤素原子和π 体系）之间形成的强结合复合物，但也包括弱供体和弱受体之间难以捉摸的相互作用（C-H···π 和 C-H···卤素）。本文还给出了一些例子，说明旋转光谱如何强调弱氢键在手性识别现象中和作为重要生物分子构象景观驱动力方面的重要性。
