Crystal Structure of a Fluoroquinolone Antibiotic, Enoxacin

Abstract

Crystals of Enoxacin, one of commercial fluoroquinolone antibiotics, were grown from acetonitrile/methanol and the crystal structure was determined. Results show that the unit cell contains two crystallographically independent molecules (A and B), three water and one methanol molecules. The carboxylic group is ionized and the N4 atom from the piperazine ring is protonated, resulting a zwitter ionic structure. The interlayer π–π interactions and the intermolecular hydrogen bonds stabilize the crystal packing.