Conformational preference of glycinamide in solution: An answer derived from combined experimental and computational studies

• The conformational preference of glycinamide has been found to be altered with the nature of solvent.
• Intramolecular hydrogen bonded conformation of glycinamide is preffered in the acetonitrile solution.
• Non-intramolecular hydrogen bonded conformation is favoured in dimethylsulfoxide medium.

Conformational problems are often subtle but very important in controlling many intricate features in chemistry and biochemistry. We have performed the conformational analysis of glycinamide using NMR experiments and computational studies. 1H NMR experiments suggest the prevalence of intramolecular hydrogen bonded conformation of glycinamide (2B) in acetonitrile, whereas, non-intramolecular hydrogen bonded conformation 2A is favoured in dimethylsulfoxide. The NOESY experiments carried out for glycinamide in DMSO-d6, showed stronger NOE interaction of the NHa-atom of amide group with CH2 than that of NHb-atom confirming the presence of conformer 2A. DFT calculations performed with explicit DMSO molecules also suggested a clear preference for the conformer 2A. The molecular dynamics simulations performed with the explicit DMSO molecules also showed that the intermolecular hydrogen bonding exists between the solvent and solute molecules to stabilize the conformer 2A. The present study sheds light on the debate of conformational preference of neutral glycinamide in the present literature.

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