Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA.
Chemistry Department, Kalamazoo College, Kalamazoo, MI, 49006, USA.
Angew Chem Int Ed Engl. 2017 Aug 7;56(33):9842-9846. doi: 10.1002/anie.201705023. Epub 2017 Jul 18.
From DNA base pairs to drug-receptor binding, hydrogen (H-)bonding and aromaticity are common features of heterocycles. Herein, the interplay of these bonding aspects is explored. H-bond strength modulation due to enhancement or disruption of aromaticity of heterocycles is experimentally revealed by comparing homodimer H-bond energies of aromatic heterocycles with analogs that have the same H-bonding moieties but lack cyclic π-conjugation. NMR studies of dimerization in C D find aromaticity-modulated H-bonding (AMHB) energy effects of approximately ±30 %, depending on whether they enhance or weaken aromatic delocalization. The attendant ring current perturbations expected from such modulation are confirmed by chemical shift changes in both observed ring C-H and calculated nucleus-independent sites. In silico modeling confirms that AMHB effects outweigh those of hybridization or dipole-dipole interaction.
从 DNA 碱基对到药物受体结合，氢键 (H-) 和芳香性是杂环的共同特征。本文探讨了这些键合方面的相互作用。通过比较具有相同氢键部分但缺乏环状π共轭的芳香杂环与类似物的同二聚体 H 键能，实验揭示了杂环芳香性增强或破坏导致 H 键强度的调制。在 C D 中对二聚化的 NMR 研究发现，芳香性调制 H 键合（AMHB）能量效应约为±30%，具体取决于它们是增强还是削弱芳香离域。从这种调制中预期的环电流扰动通过观察到的环 C-H 和计算的核独立位点的化学位移变化得到证实。计算机模拟证实，AMHB 效应大于杂化或偶极-偶极相互作用的效应。
