Molecular tuning of the closed shell C-H⋯F-C hydrogen bond

The existence of the rare six-membered and intramolecular C-H⋯F-C hydrogen-bond has been experimentally proven in the gas phase and in the solid state recently. However, the effect of the substituents on this C-H⋯F-C hydrogen-bond system has never been reported. In view of the importance of this type of C-H⋯F-C H-bonding whose weak interaction has been found critical in nanotechnology and biological systems, the nine functional groups composed of electron donating and electron withdrawing groups are inserted into this C-H⋯F-C interaction to study the group effect on the hydrogen bonding. Group effects on this C-H⋯F-C H-bonding system have been found, and their effects on the H-bonding system have been found to be tunable.