Copper(II) complexes of the fluoroquinolone antimicrobial ciproffoxacin. Synthesis, X-ray structural characterization, and potentiometric study

Department of Chemistry, University of Queensland, Brisbane, Australia.
Journal of Inorganic Biochemistry (Impact Factor: 3.44). 05/1996; 62(1):1-16. DOI: 10.1016/0162-0134(95)00082-8
Source: PubMed


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.

1 Follower
25 Reads
  • Source
    • "Compared to LVX and the mixture of LVX and Fe-P-Mt, LVXadsorbed Fe-P-Mt exhibited loss of the infrared peaks at 1724 and 1291 cm −1 , indicating that the carboxylic group might involve interaction with Fe-P-Mt. Several previous studies, based on experiments and theoretical calculations, revealed that upon strong complexation of ketone groups with metal ions, the vibration of ketone groups of FQ would shift to a lower wavenumber and the wavenumber was lower than that of the antisymmetrical COO − stretching vibration (ν as COO − ) (Wallis et al., 1996; Macías et al., 2001; Goyne et al., 2005; Neugebauer et al., 2005; Sousa et al., 2012). Goyne et al. (2005) found that when ofloxacin formed an innersphere complex with the Al center on the mineral surface, the ketone group stretch shifted downward to 1532 cm − 1 . "
    [Show abstract] [Hide abstract]
    ABSTRACT: Antibiotics have been recognized as a class of emerging pollutant. In this study, Fe-pillared montmorillonite (Fe-P-Mt) was prepared and characterized by XRF, XRD, BET, and UV–vis-DRS analyses. Adsorption of levofloxacin (LVX), afluoroquinolone antimicrobial agent, onto Fe-P-Mt was investigated as a function of contact time, LVX concentration, pH, temperature, and ionic strength by using a batch adsorption method. FT-IR spectroscopy was used to reveal the interaction of LVX and Fe-P-Mt at the molecular level. The obtained results showed that the adsorption of LVX on Fe-P-Mt followed the pseudo-second-order kinetics, and the adsorption isotherms conformed to the Langmuir model with a maxima adsorption capacity of 48.61 mg·g −1 at 25 °C. The solution pH exerted a strong influence on LVX adsorption. The maximum adsorption was found to occur around pH 7. The addition of NaCl had a minor effect on LVX adsorption, whereas the presence of NaH2PO4depressed LVX adsorption due to its stronger affinity to Fe species. The thermodynamic parameters indicated that the adsorption process was endothermic and spontaneous. The mean free energies of adsorption calculated from a D–R model, on the other hand, suggested a chemisorption process. FT-IR spectroscopic analysis further revealed that LVX was adsorbed onto Fe-P-Mt via the coordination of ketone and carboxylate functional groups with an Fe atom to form a mononuclear bidentate complex. This study indicates that pillaring montmorillonite with iron species could significantly influence its adsorption behavior and mechanism towardfluoroquinolone antimicrobial agents.
    Full-text · Article · Oct 2015 · Applied Clay Science
  • Source
    • "Me(CIP ± ) 2+ , Me(CIP ± ) 2 2+ , and Me(CIP − ·CIP ± ) + (Turel and Bukovec 1996; Wallis et al. 1996 "
    [Show abstract] [Hide abstract]
    ABSTRACT: Ciprofloxacin (CIP) can be strongly adsorbed by ferric oxides, but some influencing factors, such as multivalent cations and soil organic matter, have not been evaluated extensively. In this study, the interaction between CIP and four divalent metals (Ca, Cd, Cu, and Pb) was investigated using potentiometric titration and the results indicated that CIP can bind to the divalent metals in the following affinity order: Cu(II) > Pb(II) > Cd(II) > Ca(II). The effects of metals and fulvic acid (FA) on the adsorption behavior of CIP onto goethite surfaces were also examined using batch experiments. It was found that metal cations enhanced the CIP retention on goethite surfaces in the same order as the affinity order with CIP, indicating that metals likely increased CIP retention through cation bridging. FA was found to promote CIP sorption rather than compete with it, and the coexistence of FA and Cu(II) in the system exhibited an addictive effect with CIP sorption, indicating that they might influence the sorption separately under the studied loading condition. Taken together, our results suggested that the coexistence of divalent cations or soil organic matter will enhance CIP sorption on goethite surfaces, hence reducing its mobility and bioavailability in the environment.
    Full-text · Article · Aug 2014 · Environmental Science and Pollution Research
  • Source
    • "The solid formed was filtrated, washed with pre-cooling deionized water, and finally lyophilized. CIP(Cu)$ÂH 2 O and (CIP) 2 Cd$ÂH 2 O were prepared according to the procedures reported by Wallis et al. (1996) and López-Gresa et al. (2002), respectively. In brief, CIP was dissolved in deionized water and metallic chloride was added. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Co-contamination of ligand-like antibiotics (e.g., tetracyclines and quinolones) and heavy metals prevails in the environment, and thus the complexation between them is involved in environmental risks of antibiotics. To understand toxicological significance of the complex, effects of metal coordination on antibiotics' toxicity were investigated. The complexation of two antibiotics, oxytetracycline and ciprofloxacin, with three heavy metals, copper, zinc, and cadmium, was verified by spectroscopic techniques. The antibiotics bound metals via multiple coordination sites and rendered a mixture of various complexation speciations. Toxicity analysis indicated that metal coordination did modify the toxicity of the antibiotics and that antibiotic, metal, and their complex acted primarily as concentration addition. Comparison of EC(50) values revealed that the complex commonly was highest toxic and predominately correlated in toxicity to the mixture. Finally, environmental scenario analysis demonstrated that ignoring complexation would improperly classify environmental risks of the antibiotics.
    Full-text · Article · Apr 2012 · Environmental Pollution
Show more