Decato Daniel A, Sun Jiyu, Boller Madeleine R, Berryman Orion B
University of Montana 32 Campus Drive Missoula MT USA
Chem Sci. 2022 Aug 31;13(37):11156-11162. doi: 10.1039/d2sc03792k. eCollection 2022 Sep 28.
C-H hydrogen bonds have remarkable impacts on various chemical systems. Here we consider the influence of C-H hydrogen bonds to iodine atoms. Positioning a methyl group between two iodine halogen bond donors of the receptor engendered intramolecular C-H hydrogen bonding (HBing) to the electron-rich belt of both halogen bond donors. When coupled with control molecules, the role of the C-H hydrogen bond was evaluated. Gas-phase density functional theory studies indicated that methyl C-H hydrogen bonds help bias a bidentate binding conformation. Interaction energy analysis suggested that the charged C-H donors augment the halogen bond interaction-producing a >10 kcal mol enhancement over a control lacking the C-H⋯I-C interaction. X-ray crystallographic analysis demonstrated C-H hydrogen bonds and bidentate conformations with triflate and iodide anions, yet the steric bulk of the central functional group seems to impact the expected trends in halogen bond distance. In solution, anion titration data indicated elevated performance from the receptors that utilize C-H Hydrogen Bond enhanced Halogen Bonds (HBeXBs). Collectively, the results suggest that even modest hydrogen bonds between C-H donors and iodine acceptors can influence molecular structure and improve receptor performance.
C-H氢键对各种化学体系有着显著影响。在此，我们考虑C-H氢键对碘原子的影响。在受体的两个碘卤键供体之间引入一个甲基，会形成分子内C-H氢键与两个卤键供体的富电子带相互作用。当与对照分子结合时，对C-H氢键的作用进行了评估。气相密度泛函理论研究表明，甲基C-H氢键有助于偏向双齿结合构象。相互作用能分析表明，带电荷的C-H供体增强了卤键相互作用，相较于缺乏C-H⋯I-C相互作用的对照物，产生了超过10千卡/摩尔的增强。X射线晶体学分析证明了与三氟甲磺酸根和碘离子阴离子存在C-H氢键和双齿构象，但中心官能团的空间位阻似乎影响了卤键距离的预期趋势。在溶液中，阴离子滴定数据表明，利用C-H氢键增强卤键（HBeXBs）的受体性能有所提高。总体而言，结果表明，即使是C-H供体与碘受体之间适度的氢键也能影响分子结构并改善受体性能。
