Single-Stranded Molecular Helical Assembly from a Self-Complementary Squaramide Compound

A new helical crystal structure of a disquaramide compound has been solved by means of direct methods from powder X-ray diffraction data. It contains a racemic mixture of alternating clock/anticlockwise rotating helices which are formed through an unprecedented combination of strong squaramide–squaramide and amine–phenol interactions, both in a head-to-tail fashion.