Phosphorus-Containing Chiral Molecule for Fullerene Recognition Based on Concave/Convex Interaction

A C3-symmetric chiral concave molecule
having a phosphorus atom at the center was synthesized, and its enantiomers
were resolved. The chiral concave shape and absolute structure of
the concave molecules were revealed by X-ray analysis. The concave
molecule exhibited intense chiroptical properties with a large anisotropy,
which was derived from molecular orbitals delocalized to the side
chains. In the co-crystal with pristine C60, four of the
enantiopure concave molecules perfectly wrapped the surface of C60. MALDI-TOF mass, NMR, and circular dichromism spectra also
supported the concave/convex interaction between the concave molecule
and fullerene. These results suggest that the phosphorus-containing
molecule with a concave shape plays an important role as a chiral
host molecule for C60.