A new polymorph of bis(2‐aminopyridinium) fumarate–fumaric acid (1/1) from powder X‐ray diffraction
A new polymorph of bis(2‐aminopyridinium) fumarate–fumaric acid (1/1), 2C5H7N2 +·C4H2O4 2−·C4H4O4, was obtained and its crystal structure determined by powder X‐ray diffraction. The new polymorph (form II) crystallizes in the triclinic system (space group P
), while the previous reported
polymorph [form I; Ballabh, Trivedi, Dastidar & Suresh (2002). CrystEngComm, 4, 135–142; Büyükgüngör, Odabaşoğlu, Albayrak & Lönnecke (2004). Acta Cryst. C60, o470–o472] is monoclinic (space group P21/c).
In both forms I and II, the asymmetric unit consists of one 2‐aminopyridinium cation, half a fumaric acid molecule and half a fumarate dianion. The fumarate dianion is involved in hydrogen bonding with two neighbouring 2‐aminopyridinium cations to form a hydrogen‐bonded
trimer in both forms. In form II, the hydrogen‐bonded trimers are interlinked across centres of inversion via pairs of N—H...O hydrogen bonds, whereas such trimers are joined via single N—H...O hydrogen bonds in form I, leading to different packing modes for
forms I and II. The results demonstrate the relevance and application of the powder diffraction method in the study of polymorphism of organic molecular materials.
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Document Type: Research Article
Affiliations: College of Materials Science and Engineering, Nanjing University of Technology, No. 5 Xinmofan Road, Nanjing, People's Republic of China
Publication date: August 15, 2013