Solid-State 17 O NMR Reveals Hydrogen-Bonding Energetics: Not All Low-Barrier Hydrogen Bonds Are Strong

Jiasheng Lu; Ivan Hung; Andreas Brinkmann; Zhehong Gan; Xianqi Kong; Gang Wu

doi:10.1002/anie.201700488

Solid-State ¹⁷ O NMR Reveals Hydrogen-Bonding Energetics: Not All Low-Barrier Hydrogen Bonds Are Strong

Angew Chem Int Ed Engl. 2017 May 22;56(22):6166-6170. doi: 10.1002/anie.201700488. Epub 2017 Feb 22.

Authors

Jiasheng Lu¹, Ivan Hung², Andreas Brinkmann³, Zhehong Gan², Xianqi Kong¹, Gang Wu¹

Affiliations

¹ Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, Ontario, K7L 3N6, Canada.
² Center of Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL, 32310, USA.
³ Measurement Science and Standards, National Research Council Canada, 1200 Montreal Road, Ottawa, Ontario, K1A 0R6, Canada.

PMID: 28225158
DOI: 10.1002/anie.201700488

Abstract

While NMR and IR spectroscopic signatures and structural characteristics of low-barrier hydrogen bond (LBHB) formation are well documented in the literature, direct measurement of the LBHB energy is difficult. Here, we show that solid-state ¹⁷ O NMR spectroscopy can provide unique information about the energy required to break a LBHB. Our solid-state ¹⁷ O NMR data show that the HB enthalpy of the O⋅⋅⋅H⋅⋅⋅N LBHB formed in crystalline nicotinic acid is only 7.7±0.5 kcal mol^-1 , suggesting that not all LBHBs are particularly strong.

Keywords: energetics; low-barrier hydrogen bonds; molecular motion; oxygen; solid-state NMR spectroscopy.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, Non-U.S. Gov't