Investigations of the non-covalent interactions of arenes using phencyclone based molecular torsion balances

Several new phencyclone based molecular torsion balances designed to quantify the non-covalent interactions of arenes have been synthesized and studied. These molecular balances are atropisomeric small molecule model system that exhibit two distinct states, one with and one without an intramolecular noncovalent arene interaction. The disproportion in the populations of these two states can be used to measure the free energy of the intramolecular noncovalent interaction they present.;Three archetypes of non-covalent arene interactions were investigated interactions between the faces of two arenes (face-to-face), the edge of one arene and the face of another (edge-to-face), and the interactions of an alkyl CH and an arene (CH-pi). In each case the geometry of the interaction was observed in the solid state through model compounds. These interactions could be quantified in solution by integration of the 1H NMR spectra. The effects of variation of solvent on the observed free energy of interaction in each system was explore in simple and mixed solvent systems. In all cases these systems exhibited a non-classical solvophobic effect with more polar solvents facilitating the formation of non-covalent interactions. Variation of the size of alkyl and arene groups as well as the substituents of arene groups provided insight into the driving forces of the observed non-covalent interactions.