Spectral properties of Eu(III) compound with antibacterial agent ciprofloxacin (cfqH).: Crystal structure of [Eu(cfqH)(cfq)(H2O)4]Cl2•4.55H2O

A novel europium complex of fluoroquinolone ciprofloxacin (cfqH) with formula [Eu(cfqH)(cfq)(H2O)(4)]Cl-2 center dot 4.55H(2)O (1) was synthesized and its crystal structure determined by X-ray crystallography. The coordination number of europium is eight and in this structure two bidentate, O,O-bonded quinolone molecules and four aqua ligands are coordinated to the metal. One molecule of quinolone is anionic whereas the other is zwitterionic. Additionally, two chloride ions are also present in the structure to compensate the charge of the europium(III) whilst disordered solvent water molecules too are present. The spectral properties (IR, Raman, luminescence) of compound 1 were studied. Analysis of the Stark structure of the luminescence spectra was carried out and the scheme of the electronically excited states and photophysical processes of compound I was arranged. The spectral properties show that europium-ciprofloxacin complexes could be suitable for various applications based on their solution-state stability as measured by H-1 and F-19 NMR. (C) 2008 Elsevier Ltd. All rights reserved.