Determination of the handedness of urea inclusion compounds

Since the discovery of urea inclusion compounds (UICs) in 1940, the handedness of this chiral helical system has not been established experimentally. By studying three UIC systems containing light-atoms only, the optical rotations were first measured, and the absolute structures of the enantiomorphic domains of three UICs were determined via single crystal X-ray diffraction (SCXRD). The correlation between the optical rotation and the absolute configuration of the UICs was finally established, showcasing the power of absolute structure determination via SCXRD, which is essential in structural chemistry and pharmaceutical research.