NMR crystallography of 2-acylamino-6-[1H]-pyridones: Solid-state NMR, GIPAW computational, and single crystal X-ray diffraction studies

2-Acylamino-6-[1H]-pyridones [acyl = RCO, where R = methyl (1), ethyl (2), iso-propyl (3), tert-butyl (4), and 1-adamantyl (5)] have been synthesized and characterized by NMR spectroscopy. From three congeners, 2, 3 and 5, also single crystal X-ray structures have been solved. For these derivatives GIPAW calculations acts as a “bridge” between solid-state NMR data and calculated chemical shifts based on X-ray determined geometry. In crystals all three compounds exist as pyridone tautomers possessing similar six-membered ring structure stabilized by intramolecular CO⋯HN hydrogen bond. Theoretical GIPAW calculated and experimental 13C and 15N CPMAS NMR shifts are in excellent agreement with each other.

► The topology of supramolecular synthons was joined to give previously unknown molecules. ► The structure of subjected molecules was confirmed by 1H, 13C and 15N NMR techniques (including solid state). ► Intramolecular hydrogen bonding forces studied molecules to fold in the solid state. ► The GIPAW calculations perfectly join the X-ray derived and 13C and 15N CP MAS NMR data.