title: Polymorphs of anhydrous theophylline: stable form IV consists of dimer pairs and metastable form I consists of hydrogen-bonded chains.
abstract: The structure of a previously unreported polymorph of anhydrous theophylline (1,3-dimethyl-3,7-dihydro-1H-purine-2,6-dione), C(7)H(8)N(4)O(2), has been determined at 100 K and shown to have monoclinic symmetry with Z' = 2. The structure is named form IV and experimental observation indicates that this is the stable form of the material. The molecular packing consists of discrete hydrogen-bonded dimers similar to that observed in the monohydrate structure. The structure of form I has also been determined and consists of hydrogen-bonded chains.
authors.affiliation: School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, England.
authors.forename: Dikshitkumar
authors.initials: D
authors.lastname: Khamar
authors.forename: Robin Gavin
authors.initials: RG
authors.lastname: Pritchard
authors.forename: Ian James
authors.initials: IJ
authors.lastname: Bradshaw
authors.forename: Gillian Ann
authors.initials: GA
authors.lastname: Hutcheon
authors.forename: Linda
authors.initials: L
authors.lastname: Seton
mesh_terms: D003460:Crystallization; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D015394:Molecular Structure; D013806:Theophylline / Q000737:chemistry*
chemical_list: D013806:Theophylline