Synthesis of Twisted Anthracenes: Induction of Twist Chirality by the Planar Chiral [2.2]Paracyclophane.

Planar chiral [2.2]paracyclophane was employed as chiral scaffolds to twist an anthracene ring by tethering at its 1- and 8-positions; thus, twist chirality was induced in the anthracene moiety. The chiroptical properties of the resulting molecule, including circular dichroism (CD) and circularly polarized luminescence (CPL), were found to be derived from the twist chirality. An analogous molecule bearing long alkyl chains was a viscous liquid at ambient temperature, and its liquid film exhibited good CD and CPL profiles. Theoretical studies are carried out to determine the origin of these properties in the ground and excited states, which reproduced well the experimental results.

Construction of helical structures with planar chiral [2.2]paracyclophane: fusing helical and planar chiralities.

Optically active conjugated molecules bearing one-handed helical structures, in which two [4]helicenes or two phenanthrenes are stacked at terminal benzene moieties, were prepared using enantiopure [2.2]paracyclophane as a chiral scaffold. The obtained molecules exhibited excellent chiroptical properties such as circularly polarized luminescence with high disymmetry factors. Planar chiral pseudo-meta-disubstituted [2.2]paracyclophane was also optically resolved on the sub-gram-scale.