@article{ebisuzaki_boyle_smith_1997, title={Methylxanthines .1. Anhydrous theophylline}, volume={53}, ISSN={["0108-2701"]}, DOI={10.1107/S0108270197001960}, abstractNote={Clear crystals of anhydrous theophylline (3,7-dihydro-1,3-dimethyl-1H-purine-2,6-dione), C 7 H 8 N 4 O 2 , were grown by sublimation and the X-ray structure determined. The planar molecules are stacked in columns along [010] and are inclined at an angle of 26.05 (10)° relative to (010). The melting point has been determined to be 548.8 (5) K.}, journal={ACTA CRYSTALLOGRAPHICA SECTION C-CRYSTAL STRUCTURE COMMUNICATIONS}, author={Ebisuzaki, Y and Boyle, PD and Smith, JA}, year={1997}, month={Jun}, pages={777–779} }