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In the title compound, 4-(3-carboxy-l-cyclopropyl-6 -fluoro-1,4-dihydro -4-oxo-7 -quinolinyl ) -1 -piperazinium-magnesium hexahydrate-sulfate-water(1/0.5/1/3), (Ci7H19FN303)[Mg(H20)6]0.5SOa.3H20, the Mg 2+ ion lies on a twofold axis and adopts a nearly regular octahedral geometry. The quinolone is protonated at the terminal N atom of the piperazine residue. The H atom of the carboxylic acid group is hydrogen bonded to the carbonyl O atom, thus preventing the bonding of the metal to this part of the molecule. CommentThe title quinolone, ciprofloxacin [cf; 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-( 1 -piperazinyl)-3-quinolinecarboxylic acid] is a fluoroquinolone antibacterial agent with a wide spectrum of activity. It is known that the absorption of all quinolones appears to be significantly reduced by magnesium and aluminium antacids. Several other cations interact in a similar manner and the cause is probably chelation between the quinolone and the metal ion (Polk, 1989;Kara, Hasinoff, McKay & Campbell, 1991). Only a few crystal structures between quinolones and different metal ions (Ag +, Co 2+, Cu 2+) have been published

The purpose of this work was to determine the influence of mechanical and electrical treatment on the electrical conductivity of aqueous solutions. Solutions were treated mechanically by iteration of two steps: 1:100 dilution and vigorous shaking. These two processes were repeated until extremely dilute solutions were obtained. For electrical treatment the solutions were exposed to strong electrical impulses. Effects of mechanical (as well as electrical) treatment could not be demonstrated using electrical conductivity measurements. However, significantly higher conductivity than those of the freshly prepared chemically analogous solutions was found in all aged solutions except for those samples stored frozen. The results surprisingly resemble a previously observed weak gel-like behavior in water stored in closed flasks. We suggest that ions and contact with hydrophilic glass surfaces could be the determinative conditions for the occurrence of this phenomenon.