Assessing Benzene Dimer Interactions in Solution With a Molecular Balance.

We present a combined experimental and computational study of a 1,4/1,6-dibenzyl substituted cyclooctatetraene (COT)-based molecular balance as a model to assess the benzene dimer interactions in solution. This is accomplished by investigating the equilibrium between the unfolded 1,4- versus folded 1,6-dibenzyl COT in a variety of common organic solvents. NMR measurements demonstrate that the 1,6-COT isomer, in which the phenyl moieties are in proximity, is always favored over the unfolded and sterically less hindered 1,4-COT by ∼0.3 kcal mol-1, irrespective of solvent. Computations identify London dispersion (LD) interactions between the aromatic moieties in 1,6-COT as the main stabilizing force.