Solvent effects on amide-amide intramolecular hydrogen bonding as studied by NMR spectroscopy

Abstract

The objective of this research is to understand the conformational behavior of N-benzyl-N'-methylsuccinidiamide (1 ) in a variety of solvent systems. Diamide 1 canserve as a model for many biol. important mols. including polypeptides and proteins which contain multiple amide functional groups. In line with our interest in the conformations of simple ethane system, 1 adopts both the gauche and trans forms. Each form is quantifiable using a well-established NMR spectroscopic technique developed in our lab. In addn. to understanding the conditions leading to optimal hydrogen bonding, it is also of interest to us to elucidate the significance of sp^2-hybridized nitrogen atom of the amide in the formation of intramol. hydrogen bonds. So far, it has become evident that high fraction gauche is synonymous with intramol. hydrogen bonding, and low fraction gauche is indicative of the trans conformer to the extent of 33% if statistical preferences.