Parametrizing the Spatial Dependence of 1H NMR Chemical Shifts in π-Stacked Molecular Fragments

International Journal of Molecular Sciences

Jiří Brus¹  Jiří Czernek¹ 

[1] Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovsky Square 2, 16206 Prague, Czech Republic;

关键词: noncovalent interactions;    proton NMR;    intermolecular stacking;    GIAO;    GIPAW;   

DOI  :  10.3390/ijms21217908

来源: DOAJ

【 摘 要 】

Most recently a renewed interest in several areas has arisen in factors governing the ¹H NMR chemical shift (¹H CS) of protons in aromatic systems. Therefore, it is important to describe how ¹H CS values are affected by π-stacking intermolecular interactions. The parametrization of radial and angular dependences of the ¹H 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 ¹H CS data. The parametrization was found to be quantitatively correct for the T-shaped benzene dimers, and its limitations were discussed. Parametrized ¹H CS surfaces should become useful for providing additional restraints in the search of site-specific information through an analysis of structurally induced ¹H CS changes.

【 授权许可】

Unknown