Synthesis,Structure, and Magnetic Properties of a New Selenite Compound CdNi(SeO_3)_2(H_2O)_2

A new selenite compound CdNi(SeO_3)_2(H_2O)_2 has been obtained by a conventional hydrothermal method. This compound crystallizes in monoclinic system of space group C2/c, which exhibits a layer structure built by NiO_6 octahedra and SeO_3 trigonal pyramids running along the a-axis. The layers show a unique eight-rings hole network. The compound is stable at room temperature while the loss of H_2O molecules happens with heating above 523 K. Magnetic measurements indicate that CdNi(SeO_3)_2(H_2O)_2 is an antiferromagnet and possesses an antiferromagnetic ordering at T_N = 15 K.     

Structure and Electrical Properties of Potassium-Doped Siloxane-Poly(oxypropylene) Ormolytes

The structure and the ionic conduction properties of siloxane-poly(oxypropylene) (PPO) hybrids doped with different potassium salts (KCF₃SO₃, KI, KClO₄ and KNO₂) are reported for two polymer molecular weights (300 and 4000 g/mol), labelled PPO₃₀₀ and PPO₄₀₀₀, respectively. The doping concentration, related to the concentration of the ether type oxygen of the PPO chain, is the same whatever the salt and verifies [O]/[K] = 20. Ionic room temperature conductivity shows the highest value for the KCF₃SO₃ doped PPO₄₀₀₀ hybrid (4 × 10^{–7 –1} cm^–1). The structure of these hybrids was investigated by X-ray powder diffraction (XRPD) and X-ray absorption spectroscopy (EXAFS and XANES) at the potassium K-edge (3607 eV). XRPD results show that the hybrid matrix is always amorphous and the formation of secondary potassium phases is observed for all the samples, except for the KCF₃SO₃ doped PPO₄₀₀₀ hybrid. EXAFS results evidence a good correlation between the ionic conductivity and the presence of oxygen atoms as first neighbours around potassium.     

Structure,cyclic voltammetry and DNA-binding properties of the bis(pyridine)bis(sparfloxacinato)nickel(II) complex

The neutral mononuclear nickel(II) complex with the quinolone third-generation antibacterial drug sparfloxacin in the presence of the nitrogen-donor heterocyclic ligand pyridine has been synthesized and characterized. Sparfloxacin is deprotonated acting as a bidentate ligand coordinated to the Ni(II) ion through the ketone oxygen and a carboxylato oxygen. The crystal structure of bis(sparfloxacinato)bis(pyridine)nickel(II), 1, has been determined with X-ray crystallography. The cyclic voltammograms of the complex have been recorded in dmso solution and in 1/2 dmso/buffer (containing 150 mM NaCl and 15 mM trisodium citrate at pH 7.0) solution and the corresponding redox potentials have been estimated. The biological activity of the complex has been evaluated by examining its ability to bind to calf-thymus DNA (CT DNA) with UV and fluorescence spectroscopies and cyclic voltammetry. UV study of the DNA-interaction of the complex has shown that it can bind to CT DNA and the DNA-binding constant has also been calculated. The cyclic voltammograms of the complex in the presence of CT DNA have shown that the complex can bind to CT DNA by the intercalative mode. Competitive study with ethidium bromide (EB) has shown that the complex can displace the DNA-bound EB indicating that the complex binds to DNA in strong competition with EB for the intercalative binding site.