Direct Experimental Evidence for Halogen-Aryl pi Interactions in Solution from Molecular Torsion Balances

摘要

We dissected halogen-aryl pi interactions experimentally using a bicyclic N-arylimide based molecular torsion balances system, which is based on the influence of the non-bonded interaction on the equilibria between folded and unfolded states. Through comparison of balances modulated by higher halogens with fluorine balances, we determined the magnitude of the halogen-aryl pi interactions in our uni-molecular systems to be larger than -5.0 kJ mol(-1), which is comparable with the magnitude estimated in the biomolecular systems. Our study provides direct experimental evidence of halogen-aryl pi interactions in solution, which until now have only been revealed in the solid state and evaluated theoretically by quantum-mechanical calculations.