No abstract

A La(III) complex, [La III Cl 2 (NOR) 2 ]Cl (2), containing norfloxacin (NOR) (1), a synthetic fluoroquinolone antibacterial agent, has been synthesized and characterized by elemental analysis, IR, UV-vis spectra and 1 H NMR spectroscopy, and molar conductance measurements. The interaction between 2 and CT-DNA was investigated by steady-state absorption and fluorescence techniques in different pH media, and showed that 2 could bind to CT-DNA presumably via non-intercalative mode and the La(III) complex showed moderate ability to bind CT-DNA compared to other La(III) complexes. The binding site number n, and apparent binding constant K A , corresponding thermodynamic parameters ΔG # , ΔH # , ΔS # at different temperatures were calculated. The binding constant (K A ) values are 0.23 ± 0.05, 0.56 ± 0.05, and 0.18 ± 0.08 × 10 5 L mol −1 for pH 4, 7, and 11, respectively. It was also found that the fluorescence quenching mechanism of CT-DNA by La(III) complex was a static quenching process.