title: Copper(II) complexes of the fluoroquinolone antimicrobial ciprofloxacin. Synthesis, X-ray structural characterization, and potentiometric study.
abstract: Reaction of the fluoroquinolone antimicrobial ciprofloxacin with copper(II) nitrate in the presence of 2,2'-bipyridine resulted in the isolation of the complex [Cu(cip)(bipy) (Cl)0.7(NO3)0.3] (NO3).2H2O. Reaction of an aqueous solution of ciprofloxacin.HCl and NaCl with CuCl2 at pH 5.0 resulted in the isolation of [Cu(cip)2]Cl2.11H2O. The complex [Cu(cip) (bipy)(Cl)0.7(NO3)0.3] (NO3).2H2O crystallizes in the monoclinic space group P2(1)/n, with a = 13.955(8), b = 14.280(8), c = 14.192(6) A, beta = 93.10(4) degrees, Z = 4 with R = 0.046. The selective broadening of resonances in the 13C NMR spectrum of ciprofloxacin by the addition of Cu2+(aq) was employed to probe metal ion binding sites in the ligand. The protonation constants of norfloxacin and ciprofloxacin, and the formation constants with copper(II), were determined by potentiometric titrations at 25 degrees C. The additions of ciprofloxacin to metal to form ML and ML2 complexes exhibit stepwise formation constants of log K1 6.2(1) and log K2 11.1(3), respectively.
authors.affiliation: Department of Chemistry, University of Queensland, Brisbane, Australia.
authors.forename: S C
authors.initials: SC
authors.lastname: Wallis
authors.forename: L R
authors.initials: LR
authors.lastname: Gahan
authors.forename: B G
authors.initials: BG
authors.lastname: Charles
authors.forename: T W
authors.initials: TW
authors.lastname: Hambley
authors.forename: P A
authors.initials: PA
authors.lastname: Duckworth
mesh_terms: D000890:Anti-Infective Agents / Q000138:chemical synthesis* / Q000737:chemistry*; D002939:Ciprofloxacin / Q000138:chemical synthesis* / Q000737:chemistry*; D003300:Copper / Q000737:chemistry; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D011199:Potentiometry
chemical_list: D000890:Anti-Infective Agents; D002939:Ciprofloxacin; D003300:Copper