A new polymorph of bis(2‐aminopyridinium) fumarate–fumaric acid (1/1) from powder X‐ray diffraction. (12th July 2013)

• Record Type: Journal Article
• Authors: Dong, Shuichao; Tao, Yaqiu; Shen, Xiaodong; Pan, Zhigang
• Is Part Of: Acta crystallographica. Volume 69:Part 8(2013:Aug.)
• Page Start: 896
• Page End: 900
• Publication Date: 2013-07-12
• Subjects: Crystallography -- Periodicals; Crystals -- Periodicals; 548.05
• DOI: 10.1107/S0108270113017423
• Languages: English
• ISSNs: 0108-2701

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <p>A new polymorph of bis(2‐aminopyridinium) fumarate–fumaric acid (1/1), 2C<sub>5</sub>H<sub>7</sub>N<sub>2</sub><sup>+</sup>·C<sub>4</sub>H<sub>2</sub>O<sub>4</sub><sup>2−</sup>·C<sub>4</sub>H<sub>4</sub>O<sub>4</sub>, was obtained and its crystal structure determined by powder X‐ray diffraction. The new polymorph (form II) crystallizes in the triclinic system (space group <italic>P</italic><inline-graphic xlink:href="ark:/27927/pgg3hbw7s0s" mimetype="image" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" />), while the previous reported polymorph [form I; Ballabh, Trivedi, Dastidar & Suresh (2002). <italic>CrystEngComm</italic>, <bold>4</bold>, 135–142; Büyükgüngör, Odabaşoğlu, Albayrak & Lönnecke (2004). <italic>Acta Cryst.</italic> C<bold>60</bold>, o470–o472] is monoclinic (space group <italic>P</italic>2<sub>1</sub>/<italic>c</italic>). 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 <italic>via</italic> pairs of N—H...O hydrogen bonds, whereas such trimers are joined <italic>via</italic> 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.</p> </abstract>