Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovsky Square #2, 16206 Prague, Czech Republic.
Int J Mol Sci. 2020 Oct 24;21(21):7908. doi: 10.3390/ijms21217908.
Most recently a renewed interest in several areas has arisen in factors governing the H NMR chemical shift (H CS) of protons in aromatic systems. Therefore, it is important to describe how H CS values are affected by π-stacking intermolecular interactions. The parametrization of radial and angular dependences of the H CS is proposed, which is based on conventional gauge-independent atomic orbital (GIAO) calculations of explicit molecular fragments. Such a parametrization is exemplified for a benzene dimer with intermonomer vertical and horizontal distances which are in the range of values often found in crystals of organic compounds. Results obtained by the GIAO calculations combined with B3LYP and MP2 methods were compared, and revealed qualitatively the same trends in the H CS data. The parametrization was found to be quantitatively correct for the T-shaped benzene dimers, and its limitations were discussed. Parametrized H CS surfaces should become useful for providing additional restraints in the search of site-specific information through an analysis of structurally induced H CS changes.
最近，人们对控制芳香体系质子 H NMR 化学位移（H CS）的因素重新产生了兴趣。因此，描述 H CS 值如何受到π-堆积分子间相互作用的影响非常重要。提出了一种基于常规无规范原子轨道（GIAO）计算显式分子片段的 H CS 径向和角度依赖性参数化方法。这种参数化方法以单体间垂直和水平距离在有机化合物晶体中常见值范围内的苯二聚体为例进行了说明。通过 GIAO 计算与 B3LYP 和 MP2 方法相结合得到的结果进行了比较，定性地揭示了 H CS 数据中的相同趋势。该参数化方法对于 T 形苯二聚体是定量正确的，并讨论了其局限性。参数化 H CS 曲面应该在通过分析结构诱导的 H CS 变化来搜索特定位置信息时成为提供附加约束的有用工具。
