Effect of a Rigid Sulfonamide Bond on Molecular Folding: A Case Study

A disulfonamide compound with bulky
aromatic side chains was prepared,
and its properties as a potential building block for foldamers were
evaluated. Two different solvate crystal forms of the compound were
identified and compared to the structures of an analogous oligoamide
and related disulfonamides. The disulfonamide is unfolded in one of
the solvates, whereas in the other one, a loosely folded conformer
stabilized by an intramolecular hydrogen bond is found. Density functional
calculations indicated that the loosely folded conformer is slightly
more stable than its unfolded isomer. The calculations also identified
a third, more tightly folded and more extensively hydrogen bonded,
conformer that is even lower in energy.