Structural Studies on Complexes IV: Crystal Structure of a 1:1 5-Chlorosalicylic Acid and Theophylline Complex

Single crystal X-ray diffraction methods were utilized in obtaining the crystal and molecular structure of a 1:1 association complex between 5-chlorosalicylic acid and theophylline. The crystals are monoclinic (space group P 21/c) with cell parameters of a = 7.845 Å b = 9.636 Å c = 21.185 Å and β =...

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Bibliographic Details
Published in:Journal of pharmaceutical sciences 1969-06, Vol.58 (6), p.710-714
Main Author: Shefter, Eli
Format: Article
Language:English
Subjects:
5-Chlorosalicylic acid-theophylline complex-crystal
5-Chlorosalicylic acid-theophylline complex—crystal, molecular structure
Chemical Phenomena
Chemistry
Complexes-structural studies
Diffractometry-5-chlorosalicylic acid-theophylline complex
Hydrogen
Hydrogen bonding-5-chlorosalicylic acid-theophylline complex
Models, Structural
molecular structure
Salicylates - analysis
Temperature
Theophylline - analysis
X-Ray Diffraction
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Summary:Single crystal X-ray diffraction methods were utilized in obtaining the crystal and molecular structure of a 1:1 association complex between 5-chlorosalicylic acid and theophylline. The crystals are monoclinic (space group P 21/c) with cell parameters of a = 7.845 Å b = 9.636 Å c = 21.185 Å and β = 92.20° The crystals contain a significant fraction of the impurities 3,5-dichloro- and 3-chlorosalicylic acid. Hydrogen bonds are the major attractive forces between the components of the complex. A relatively strong hydrogen bond exists between the carboxyl group of 5-chlorosalicylic acid and N(9) of theophylline (2.682 A.). The theophylline molecules are in a dimeric arrangement by virtue of centrosymmetrically related hydrogen bonds between N(7) and TO(10). The packing arrangement of the molecules suggests that the stacking forces are similar to those in a caffeine: 5-chlorosalicylic acid complex.
ISSN:0022-3549
1520-6017
DOI:10.1002/jps.2600580613