Date Published: August 01, 2012
Publisher: International Union of Crystallography
Author(s): Elena Rusu, Sergiu Shova, Gheorghe Rusu.
The title compound, 3C10H8N4·2C7H6O5·2CH4O, has a molecular crystal structure which results from the cocrystallization of gallic acid (GA), 4,4′-azodipyridine (AzPy) and methanol in a 2:3:2 molar ratio. The asymmetric unit comprises one molecule each of GA, AzPy and methanol in general positions and half a molecule of AzPy as this is located about a centre of inversion. In the crystal, all the components of the structure are associated via the extended system of hydrogen bonds (O—H⋯O and O—H⋯N) and π–π stacking interactions [centroid–centroid distance = 3.637 (3) Å] into two-dimensional supramolecular layers which are packed parallel to the  plane. The shortest perpendicular distance and the slippage between aromatic groups are 3.395 (3) and 2.152 (3) Å, respectively. The AzPy molecules display a trans conformation with respect to the azo groups.
For the photosensitive properties of azo compounds, see: Qiu et al. (2011 ▶). For potential applications of gallic acid, see: Fazary et al. (2009 ▶). For the synthesis and cocrystallization ability of 4,4′-azodipyridine, see: Launay et al. (1991 ▶); Zhuang et al. (2006 ▶); Kanoo et al. (2012 ▶).