Studies on hydrogen bonding interaction in various systems, involving phenylacetylene (PhAc), propargyl alcohol (PA), borazine (BNH), propargyl amine (PAm) were performed using matrix isolation infrared spectroscopy and supported by ab initio computations. Weak intermolecular interactions of the above mentioned precursors with water, methanol, ether, acetylene and benzene were studied. These systems manifested O–H··· $$ \uppi $$ π and n – $$ {{\upsigma}^{*}} $$ σ ∗ interactions, such as C–H···O, N–H···O, O–H···O and O–H···N. In several cases the complexes were multiply tethered involving two or more of the above mentioned contacts. Many of the weak complexes exhibited a number of isomers, and the relative importance of the multiple non-covalent contacts resulted in a competition between the various isomers for the global minimum. It was found that subtle changes in the structures of the precursors tilted the balance towards one isomer or the other. Our studies also threw up a systematic method of building possible structures for complex systems starting from the known structures of related simple systems. We also studied the homodimers of PA and BNH. The BNH dimer was particularly interesting as one of its isomers was characterized by a bis-dihydrogen bond. We also studied the influence of hydrogen bonding interactions in determining the conformational landscape and preference in amino acids. Here again we were able to draw some generalizations regarding the conformational stability of amino acids. The combination of matrix isolation and ab initio computation is a powerful tool for studies on weak intermolecular interactions and conformations.

中文翻译：

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由氢键引导的分子间复合物和分子构象：基质分离和 Ab Initio 研究

使用基质隔离红外光谱并由 ab initio 计算支持，对各种系统中的氢键相互作用进行了研究，包括苯乙炔 (PhAc)、炔丙醇 (PA)、硼嗪 (BNH)、炔丙胺 (PAm)。研究了上述前体与水、甲醇、乙醚、乙炔和苯的弱分子间相互作用。这些系统表现出 O–H… $$ \uppi $$ π 和 n – $$ {{\upsigma}^{*}} $$ σ ∗ 相互作用，例如 C–H…O, N–H ···O、O-H···O 和 O-H···N。在一些情况下，复合物被多重束缚，涉及两个或多个上述接触。许多弱配合物表现出许多异构体，并且多个非共价接触的相对重要性导致了各种异构体之间对全局最小值的竞争。发现前体结构的细微变化使天平向一种异构体或另一种异构体倾斜。我们的研究还提出了一种从相关简单系统的已知结构开始为复杂系统构建可能结构的系统方法。我们还研究了 PA 和 BNH 的同型二聚体。BNH 二聚体特别有趣，因为它的一种异构体以双二氢键为特征。我们还研究了氢键相互作用在确定氨基酸的构象景观和偏好方面的影响。在这里，我们再次能够对氨基酸的构象稳定性进行一些概括。矩阵分离和从头计算的结合是研究弱分子间相互作用和构象的有力工具。