Chiral Moieties-Oriented Single-Stranded Helical Assembly of Calix[4]azacrown Derivatives

Bridging of calix[4]arene derivatives with optically active subunits derived from chiral l/d-amino alcohols has resulted in two novel calix[4]azacrowns enantiomers S-C51H64NO7·CH3OH·H2O (S-1) and R-C51H64NO7·CH3OH·H2O (R-1), which were crystallized separately. Single crystal X-ray diffraction studies revealed that they each encapsulate a methanol molecule by weak interactions and that they form supramolecular enantiomeric helical arrangements along the crystallographic axis, which are constructed via C–H···O hydrogen bonds involving bridging water molecules. A similar helical arrangement was also found in the crystal structure of a previously reported calix[4]azacrown compound S-C108H146N2O16 (S-2).