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.