Acid-induced molecular folding and unfolding of N-methyl aromatic amide bearing 2,6-disubstituted pyridines

The structural features and conformational conversion of the N-methyl pyridyl amide oligomer bearing 2,6-disubstituted pyridines were investigated. H-1 NMR and X-ray crystallography revealed that the environment-responsive type of conformational control can be performed. The amide bond switching together with intramolecular hydrogen-bonding effects caused dynamic protonation-associated conformational conversion from layered to spiral and then flat.