van der Waals interactions to control amide cis–trans isomerism†
Abstract
We discover the presence of local van der Waals (vdW) interactions at the cis amide bond in crystals of isobutyroyl–Pro–Val–OMe. By expanding this interaction volume, we demonstrate a corresponding sigmoidal increase in cis amide stabilization by up to −0.24 kcal mol−1. These vdW interactions exhibit a 60% contribution towards similar CH⋯π interaction energies.