title: Conformational polymorphism of (E,E)-N,N'-bis(4-nitrobenzylidene)benzene-1,4-diamine.
abstract: Two polymorphs of (E,E)-N,N'-bis(4-nitrobenzylidene)benzene-1,4-diamine, C(20)H(14)N(4)O(4), (I), have been identified. In each case, the molecule lies across a crystallographic inversion centre. The supramolecular structure of the first polymorph, (I-1), features stacking based on π-π interactions assisted by weak hydrogen bonds involving the nitro groups. The second polymorph, (I-2), displays a perpendicular arrangement of molecules linked via the nitro groups, combined with weak C-H···O hydrogen bonds. Both crystal structures are compared with that of the carbon analogue (E,E)-1,4-bis[2-(4-nitrophenyl)ethenyl]benzene, (II).
authors.affiliation: Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.
authors.forename: Alain
authors.initials: A
authors.lastname: Collas
authors.forename: Matthias
authors.initials: M
authors.lastname: Zeller
authors.forename: Frank
authors.initials: F
authors.lastname: Blockhuys