Enantioselective molecular recognition in a flexible self-folding cavitand

We report a chiral deep cavitand receptor based on calix[5]arene stabilized by a cooperative network of hydrogen bonds and having a highly flexible structure. The dynamic features of the host have been studied by 1H NMR spectroscopy, revealing a bowl inversion motion that is slow in the NMR time scale. The cavitand displays enantioselective molecular recognition with a series of chiral quaternary ammonium salts, providing unprecedented stability ratios between the corresponding diasteromeric host-guest complexes. Molecular dynamics simulations corroborate the higher flexibility of the new host and the emergence of superior induced fit behavior with regards to resorcin[4]arene derived self-folding cavitands.