title: 4,4'-Dinitro-2,2'-[propane-1,3-diylbis(iminiumylmethanylyl-idene)]diphenolate.
abstract: The title compound, C(17)H(16)N(4)O(6), is a Schiff base, which is found as a bis-zwitterion in the solid state. The geometry around the iminium N atom indicates sp(2)-hybridization. The diiminiumpropyl-ene chain is in an approximate double-gauche conformation, with average N-C-C-C torsion angles of 69.3°. The zwitterion shows strong intra-molecular N-H⋯O hydrogen bonds between the iminium N and phenolate O atom. In the crystal, bifurcated N-H⋯(O,O) hydrogen bonds assemble pairs of molecules into inversion dimers.
authors.affiliation: School of Applied Chemical Engineering, The Research Institute of Catalysis, Chonnam National University, Gwangju 500-757,  Republic of Korea.
authors.forename: Kwang
authors.initials: K
authors.lastname: Ha