Four salt phases of theophylline

Amanda Buist, Alan Kennedy, Craig Manzie

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The structures of two anhydrous salt phases of theophylline, namely 1,3-dimethyl-2,6-dioxo-7H-purin-9-ium tetra­fluoro­borate, C7H9N4O2+·BF4-, and 1,3-dimethyl-2,6-dioxo-7H-purin-9-ium chloride, C7H9N4O2+·Cl-, are reported together with the structures of two monohydrate salt forms, namely 1,3-dimethyl-2,6-dioxo-7H-purin-9-ium chloride monohydrate, C7H9N4O2+·Cl-·H2O, and 1,3-dimethyl-2,6-dioxo-7H-purin-9-ium bromide monohydrate, C7H9N4O2+·Br-·H2O. The monohydrate structures are mutually isostructural, with the cations and anions lying on crystallographic mirror planes (Z' = 1\over 2). The main inter­molecular inter­action motif is a hydrogen-bonding network in the same mirror plane. The tetra­fluoro­borate structure is based on planar hydrogen-bonded theopylline cation dimers; the anions inter­act with the dimers in a pendant fashion. The anhydrous chloride structure has Z' = 2 and in contrast to the other species it does not form planar hydrogen-bonded constructs, instead one-dimensional chains of cations and anions propagate parallel to the crystallographic c direction. An earlier report claiming to describe an anhydrous structure of theophylline hydro­chloride is re-examined in light of these results. It is concluded that the earlier structure has been reported in the wrong space group and that it has been chemically misidentified.
LanguageEnglish
Pages220-224
Number of pages5
JournalActa Crystallographica Section C: Crystal Structure Communications
Volume70
Issue number2
DOIs
Publication statusPublished - 15 Feb 2014

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Theophylline
Chlorides
Salts
Anions
Cations
Borates
Dimers
Hydrogen
Mirrors
Hydrogen Bonding
Bromides
Hydrogen bonds

Keywords

  • crystal structure
  • theophylline salts
  • 1,3-dimethyl-2,6-dioxo-7H-purin-9-ium
  • hydrogen bonding

Cite this

Buist, Amanda ; Kennedy, Alan ; Manzie, Craig. / Four salt phases of theophylline. In: Acta Crystallographica Section C: Crystal Structure Communications. 2014 ; Vol. 70, No. 2. pp. 220-224.
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Four salt phases of theophylline. / Buist, Amanda; Kennedy, Alan; Manzie, Craig.

In: Acta Crystallographica Section C: Crystal Structure Communications, Vol. 70, No. 2, 15.02.2014, p. 220-224.

Research output: Contribution to journalArticle

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AU - Buist, Amanda

AU - Kennedy, Alan

AU - Manzie, Craig

PY - 2014/2/15

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N2 - The structures of two anhydrous salt phases of theophylline, namely 1,3-dimethyl-2,6-dioxo-7H-purin-9-ium tetra­fluoro­borate, C7H9N4O2+·BF4-, and 1,3-dimethyl-2,6-dioxo-7H-purin-9-ium chloride, C7H9N4O2+·Cl-, are reported together with the structures of two monohydrate salt forms, namely 1,3-dimethyl-2,6-dioxo-7H-purin-9-ium chloride monohydrate, C7H9N4O2+·Cl-·H2O, and 1,3-dimethyl-2,6-dioxo-7H-purin-9-ium bromide monohydrate, C7H9N4O2+·Br-·H2O. The monohydrate structures are mutually isostructural, with the cations and anions lying on crystallographic mirror planes (Z' = 1\over 2). The main inter­molecular inter­action motif is a hydrogen-bonding network in the same mirror plane. The tetra­fluoro­borate structure is based on planar hydrogen-bonded theopylline cation dimers; the anions inter­act with the dimers in a pendant fashion. The anhydrous chloride structure has Z' = 2 and in contrast to the other species it does not form planar hydrogen-bonded constructs, instead one-dimensional chains of cations and anions propagate parallel to the crystallographic c direction. An earlier report claiming to describe an anhydrous structure of theophylline hydro­chloride is re-examined in light of these results. It is concluded that the earlier structure has been reported in the wrong space group and that it has been chemically misidentified.

AB - The structures of two anhydrous salt phases of theophylline, namely 1,3-dimethyl-2,6-dioxo-7H-purin-9-ium tetra­fluoro­borate, C7H9N4O2+·BF4-, and 1,3-dimethyl-2,6-dioxo-7H-purin-9-ium chloride, C7H9N4O2+·Cl-, are reported together with the structures of two monohydrate salt forms, namely 1,3-dimethyl-2,6-dioxo-7H-purin-9-ium chloride monohydrate, C7H9N4O2+·Cl-·H2O, and 1,3-dimethyl-2,6-dioxo-7H-purin-9-ium bromide monohydrate, C7H9N4O2+·Br-·H2O. The monohydrate structures are mutually isostructural, with the cations and anions lying on crystallographic mirror planes (Z' = 1\over 2). The main inter­molecular inter­action motif is a hydrogen-bonding network in the same mirror plane. The tetra­fluoro­borate structure is based on planar hydrogen-bonded theopylline cation dimers; the anions inter­act with the dimers in a pendant fashion. The anhydrous chloride structure has Z' = 2 and in contrast to the other species it does not form planar hydrogen-bonded constructs, instead one-dimensional chains of cations and anions propagate parallel to the crystallographic c direction. An earlier report claiming to describe an anhydrous structure of theophylline hydro­chloride is re-examined in light of these results. It is concluded that the earlier structure has been reported in the wrong space group and that it has been chemically misidentified.

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