Bile acid-derived molecular tweezers: Study of solvent effects in binding, and determination of thermodynamic parameters by an extraction-based protocol

A family of bile acid-based molecular tweezers (1-3) were synthesized, and their binding affinities with picric acid in different solvents were evaluated using a simple extraction-based protocol. The binding affinities increased in nonpolar solvents. The size of the solvent molecule did not affect the binding constant. Thermodynamic parameters for the binding of picric acid in CCl4 were also determined by this method. Binding constants of these tweezers with trinitrofluorenone in CDCl3 were determined by NMR titration.