Cocrystals of 2,3,5,6-tetrafluorobenzene-1,4-diol with diaza aromatic compounds.

2,3,5,6-Tetrafluorobenzene-1,4-diol easily forms cocrystals with heteroaromatic bases containing the pyrazine unit. In the 1:1 complexes with pyrazine, C(6)H(2)F(4)O(2) x C(4)H(4)N(2), (I), and quinoxaline, C(6)H(2)F(4)O(2) x C(8)H(6)N(2), (II), the crystal components are linked via O-H...N hydrogen bonds into one-dimensional chains. With the largest base, phenazine, the 1:2 benzenediol-phenazine complex, C(6)H(2)F(4)O(2) x 2 C(12)H(8)N(2), (III), was obtained, with the molecules linked via O-H...N interactions into a discrete heterotrimer. In all three cocrystals, the two types of molecules are organized into layers via softer C-H...O and C-H...F interactions and pi-pi stacking interactions, with stronger hydrogen bonds linking molecules of adjacent layers. In (II) and (III), molecules are arranged into heterostacks, whereas in (I) separate stacks are formed by the heterocyclic base and the benzenediol molecule.