Lamellar Twinning Explains the Nearly Racemic Composition of Chiral, Single Crystals of Hexahelicene

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Science  13 Nov 1981:
Vol. 214, Issue 4522, pp. 795-797
DOI: 10.1126/science.214.4522.795


Solvent etching of single crystals of hexahelicene grown from a racemic solution reveals an unusual layer-like pattern in which pure (+)- and pure (–)-layers alternate through the crystal; this arrangement results in a nearly racemic composition although the crystal is ostensibly chiral, space group P212121. Etched crystals of enantiomerically pure hexahelicene display no such pattern. The two kinds of crystal are indistinguishable by x-ray diffraction.