Measurement of Solvent OH−π Interactions Using a Molecular Balance

A molecular torsion balance was designed to study and measure OH−π interactions between protic solvents and aromatic surfaces. These specific solvent–solute interactions were measured via their influence on the folded–unfolded equilibrium of an N-arylimide rotor. Protic solvents displayed systematically weaker solvophobic interactions than aprotic solvents with similar solvent cohesion parameters. This was attributed to the formation of OH−π interactions between the protic solvents and the exposed aromatic surfaces in the unfolded conformer that offset the stronger solvophobic effects for protic solvents.