Research Article: 1,2-Bis(pyridin-4-yl)diazene–3,4,5-trihy­droxy­benzoic acid–methanol (3/2/2)

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 [101] 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.

Partial Text

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 ▶).




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