A 2:1 co-crystal of 3,5-di-bromo-4-cyano-benzoic acid and anthracene.

The title co-crystal, C8 H3 Br2 NO2 ·0.5C14 H10 , was self-assembled from a 2:1 mixture of the components in slowly evaporating di-chloro-methane. The mol-ecules adopt a sheet structure parallel to (1-12) in which carb-oxy hydrogen-bonded dimers and anthracene mol-ecules stagger in both dimensions. Within the sheets, six individual cyano acid mol-ecules surround each anthracene mol-ecule. Cyano acid mol-ecules form one of the two possible R 2 2 (10) rings between neighboring cyano and bromo groups. Compared to the di-chloro analog [Britton (2012 ▸). J. Chem. Crystallogr. 42 , 851-855], the dihedral angle between the best-fit planes of acid and anthracene mol-ecules has decreased from 7.1 to 0.9 (2)°.