Chiral discrimination in hydrogen-bonded

A series of racemic [7]helicenes have been prepared and characterized both in solution and in the solid state. Despite the helicenes having the ability to self-assemble in a variety of stereochemical and topological relationships, they formed only enantiomerically pure dimers held together by two pairs of cooperative hydrogen bonds. The self-assembly process was enantiospecific in solution and diastereoselective in the crystal.