Hydrogen bonded networks in hydrophilic channels: crystal structure of hydrated ciprofloxacin lactate and comparison with structurally similar compounds

Abstract

Ciprofloxacin Lactate {4-(3-carboxy-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-quinolinyl-)-1-piperazinium-lactate-water(1/1/1.5)}(C₂₀H₂₄N₃O₆F₁.5H₂O) belonging to the family of fluoroquinolone antibacterial agents with wide spectrum activity has been studied using single crystal X-ray diffraction techniques. The crystal structure has channels running along crystallographic b-axis with π-stacks of Ciprofloxacin moieties linked through water molecules. A ten-membered hydrogen bonded pattern formed by centrosymmetrically related lactate and water molecules fill the center of the channel. The molecular assembly viewed down the b-axis depicts an infinitely extended open framework channels with the major diameter of about 10.60 Å and minor diameter of 4.79 Å. The structure also has a C-H…F intramolecular interaction and an intramolecular hydrogen bond. Analysis of the structures containing 7-piperazin-1-oyl-quinolin-4(1H)-one moiety using the Cambridge Structural Database reveals that a majority of the structures show the propensity to form channels via π…π interactions. Also, a detailed comparative study with the structure of magnesium sulfate adduct of ciprofloxacin shows that such interactions lead to similar molecular assemblies.