August 2013 issue
Cover illustration: The crystal structure of 2-hydroxy-N'-methyl-5-nitrobenzohydrazide, C8H9N3O4, shows the highly unusual situation of one neutral and one zwitterionic molecule in its asymmetric unit. The zwitterion contains an intramolecular N-HO hydrogen bond and the neutral molecule features both intramolecular N-HO and O-HO hydrogen bonds. In the crystal, the constituents are linked by N-HO and N-HN hydrogen bonds to generate a two-dimensional network. See: Yang, Jin, Zhou & Jin [Acta Cryst. (2013). E69, o1305].