A Rigid Molecular Balance for Measuring Face-to-Face Arene−Arene Interactions

A new molecular balance was developed to measure face-to-face arene−arene interactions. The balance adopts distinct folded and unfolded conformations due to restricted rotation about a Caryl−Nimide bond. In the folded conformer, the rigid bicyclic framework enforces an offset face-to-face geometry to the exclusion of edge-to-face geometries, which was verified by X-ray crystallography. Measurement of the folded to unfolded ratio yields accurate values for the arene−arene interaction in a range of different solvents.