Unraveling the Role of Alkyl F on CH-pi Interactions and Uncovering the Tipping Point for Fluorophobicity

Abstract

Although fluorine often plays an influential role in molecular recognition, little is known about the effect of aliphatic fluorine on the CH-pi interaction in solution. A series of molecular balances were synthesized that contain fluorinated and nonfluorinated alkyl groups. Our findings indicate that fluorine's polarizing ability does enhance CH-7r binding and depends on molecular orientation. Surprisingly, when the terminal end of the alkyl group is completely fluorinated, the balance tips toward fluorophobicity and assumes an unusual constrained conformation.