Abstract/Summary

The title solvate, C7H8N4O2 center dot C2H6OS, was obtained unintentionally from a cocrystal screen involving theophylline and isophthalic acid. One molecule each of theophylline and dimethyl sulfoxide is present in the asymmetric unit. The packing consists of molecular sheets lying parallel to the ( 040) series of lattice planes, in which each theophylline molecule is hydrogen bonded to one dimethyl sulfoxide molecule through an N-H center dot center dot center dot O [2.7658 (15) angstrom] hydrogen bond. This particular hydrogen-bond donor was found to be used in this type of interaction in a variety of other crystal structures of theophylline.