title: A monoclinic polymorph of theophylline.
abstract: A monoclinic polymorph of theophylline, C(7)H(8)N(4)O(2), has been obtained from a chloro-form/methanol mixture by evaporation under ambient conditions. The new polymorph crystallizes with two mol-ecules in the asymmetric unit. The structure features inter-molecular N-H⋯O hydrogen bonds, resulting in the formation of dimers between two crystallographically different mol-ecules; each mol-ecule acts as both donor and acceptor.
authors.forename: Shuo
authors.initials: S
authors.lastname: Zhang
authors.forename: Andreas
authors.initials: A
authors.lastname: Fischer