A Water-Soluble Molecular Tweezer Xanthone Receptor for Carboxylates and Nucleotide Bases

Carboxylate groups are widely present in biomolecules, and they play an important role as key building blocks in organic chemistry. In this work, a new water-soluble molecular receptor for carboxylates, based on the xanthone skeleton decorated with naphthalene units acting as molecular tweezers, is reported. The xanthone skeleton provides linear NH bonds emulating the geometry found in many hydrolases, while the molecular tweezer scaffold creates the hydrophobic region, which allows the association of hydrophobic guests in water. X-ray diffraction studies for some receptor intermediates prove the right geometry of the oxyanion hole, where the combination of hydrogen bonds with the hydrophobic cavity has allowed the association of carboxylates as well as nucleotide bases in water with association constants up to 476 M–1.