A fluorescent bicyclic calix[4]arene–oxacyclophane with planar chirality: resolution, chiroptical properties, and absolute configuration

Planar chiral desymmetrization of a two-layered cyclophane and control of dynamic helicity through the arrangement of two nonstereogenic centers

Dynamic helicity generated in a configurationally stable cyclophane is controlled through the arrangement of two nonstereogenic centers with different dimensions.

Inherently chiral calix[4]arenes with planar chirality: two new entries to the family

The synthesis of two new inherently chiral calix[4]arenes (ICCs, 1 and 2), endowed with electron-rich concave surfaces, has been achieved through the desymmetrization of a lower rim distal-bridged oxacyclophane (OCP) macrocycle. The new highly emissive ICCs were resolved by chiral HPLC, and the enantiomeric nature of the isolated antipodes proved by electronic circular dichroism (CD). Using time-dependent density functional calculations of CD spectra, their absolute configurations were established. NMR studies with (S)-Pirkle’s alcohol unequivocally showed that the host-guest interactions occur in the chiral pocket comprehending the calix-OCP exo cavities and the carbazole moieties.