Carbocyclic molecular clefts incorporating hydrogen bonding features

Chiral carbocyclic cleft molecules incorporating carbonyl, hydroxy, oxime, o-phenol and m-nitroaryl groups have been synthesised from dibenzobicyclo[b,f][3.3.1]nona-5a,6a-diene-6,12-dione, a carbocyclic analogue of Tröger's base. These clefts contain similar features to Tröger's base but in addition contain carbonyl groups, which are readily modified, on the chiral bridge that forms the molecular cleft. The oxime and m-nitroaryl derivatives have been characterised by single crystal X-ray diffraction. The dihedral angles between the two aromatic rings of these two molecules and those of previously reported related molecules are compared. Two crystal packing motifs are identified and found to influence the size of the dihedral cleft angle of this type of molecule.