title: New polymorphs of an old drug: conformational and synthon polymorphism of 5-nitrofurazone.
abstract: Two new polymorphic forms of 5-nitrofurazone (5-nitro-2-furaldehyde semicarbazone) have been synthesized and structurally characterized by single-crystal and powder X-ray diffraction methods, vibrational spectroscopy (FT-IR and temperature Raman), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and Hirshfeld surface analysis. The compound crystallizes in three different polymorphic forms P21/a (polymorph α), P21 (polymorph β) and P21/c (polymorph γ), the crystal structures of two of which (polymorphs β and γ) represent new structure determinations. The solid-state molecular organization in the three crystal forms is analyzed and discussed in terms of molecular conformation, crystal packing and hydrogen-bonded networks. All three crystals are formed from trans geometrical isomers, but the molecular conformation of the α-polymorph is syn-anti-anti-anti, while that of β- and γ-polymorphs is syn-anti-syn-syn. As a consequence of this the hydrogen-bond donor and acceptor sites of the molecules are oriented differently, which in turn results in different hydrogen-bond connectivity and packing patterns.
authors.affiliation: Department of Chemistry, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, Wroclaw 50-370, Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Pogoda
authors.affiliation: Institute of Low Temperature and Structural Research, Polish Academy of Sciences, Okólna 2, Wroclaw, PO Box 1410, Poland.
authors.forename: Jan
authors.initials: J
authors.lastname: Janczak
authors.affiliation: Department of Chemistry, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, Wroclaw 50-370, Poland.
authors.forename: Veneta
authors.initials: V
authors.lastname: Videnova-Adrabinska
mesh_terms: D000890:Anti-Infective Agents / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008968:Molecular Conformation; D009583:Nitrofurazone / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D000890:Anti-Infective Agents; D009583:Nitrofurazone
keywords: hydrogen-bonded network; molecular conformation; synthon polymorphism