The crystal structure of 2-picolinic acid is known at room temperature be C2/c with zigzag chains of picolinic acid molecule connected by hydrogen-bonds with the protons disordered about the twofold axis. There are no fewer than eight possible structural configurations available based on the O-H�O and N-H�N hydrogen bonding arrangement. 15N-CP/MAS NMR spectrum revealed that two separate protonated and unprotonated N signals. Solid-state density functional theory and 25 K INS spectroscopy lead to only one possible combination of staggered neutral and zwitterionic forms and excellent agreement between observed and computed spectra.  Parabanic acid has been used to test the ability of solid-state DFT to accurately reproduce hydrogen-bonding. While the simulated spectra account for relative intensities and factor group splitting regardless of functional choice, the H-bending vibrational energies for the out-of-plane modes are poorly described by all methods.  The disagreement between calculated and observed out-of-plane hydrogen bending modes is examined.

INS vibrational spectroscopy of parabanic and picolinic acid: Hydrogen-bonding in the solid-state

239th National Meeting (2010)

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