Crystal structure of danofloxacin mesylate (C19H21FN3O3)(CH3O3S)

Abstract

The crystal structure of danofloxacin mesylate has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional theory techniques. Danofloxacin mesylate crystallizes in space groupP1(#1) witha= 6.77474(8),b= 12.4973(4),c= 12.82826(28) Å,α= 84.8709(29),β= 87.7501(10),γ= 74.9916(4)°,V= 1044.723(11) Å3, andZ= 2. The protonation of the danofloxacin cations was established by the analysis of potential intermolecular interactions and differs from that expected from isolated-cation calculations. The crystal structure consists of alternating layers of cations and anions parallel to theac-plane. There is parallel stacking of the oxoquinoline rings along thea-axis. The expected N–H⋯O hydrogen bonds between the cations and anions are not present. Each cation makes an N–H⋯O hydrogen bond with the other cation, resulting in zig-zag chains along thea-axis. Both cations have strong intramolecular O–H⋯O hydrogen bonds. There are several C–H⋯O hydrogen bonds between the danofloxacin cations and mesylate anions. The powder pattern has been submitted to ICDD® for inclusion in the Powder Diffraction File™ (PDF®).