Control of a Chiral Property of a Calix[3]aramide: The Racemization Suppressed by Intramolecular Cyclic Hydrogen Bonds and DMSO–H₂O System-Induced Spontaneous Resolution

A calix[3]­aramide has been synthesized bearing three triphenylphosphinic amide moieties, which formed intramolecular cyclic hydrogen bonds that suppressed its cone/partial cone inversion. The intramolecular cyclic hydrogen bonds were disrupted by DMSO, and the insertion of H₂O into the hydrogen bonds triggered the spontaneous resolution of the calix[3]­aramide. Within a chiral environment, such as that afforded by the presence of optically active 2-butanol, the calix[3]­aramide underwent a symmetry breaking crystallization process.