Modification of chitin with high adsorption capacity for methylene blue removal.

Porous chitin sorbents (PChs) with different content of chitin, ranging from 0.9% to 3.5%, were prepared by gel method with CaBr2·xH2O/CH3OH solution and characterized by FT-IR, XRD and SEM. The adsorption isotherms and kinetic analysis of methylene blue (MB) onto PChs were studied. Experimental results illustrated lower crystallinity and more pores of PChs containing 3.5% chitin displayed higher adsorption capacity, the removal of MB was 79.8%. The adsorption equilibrium isotherm curve of MB onto PChs adsorbents conformed to the Freundlich equation. The PFO, PSO and Weber-Morris models were applied to fit with the adsorption kinetics. The results demonstrated the adsorption of MB might be the mass transfer of heterogeneous system and involve multiple diffusion steps. The adsorption capacity of PChs with 3.5% chitin can maintain 65% removal ratio of MB after being used six adsorption-desorption cycles. It was supposed that PChs may be a promising, cheap, environmentally friendly and efficient adsorbent for some dye wastewater treatment in the near future.

(2-Acetyl-phenolato)(2,2'-bipyridine)nitratocopper(II).

In the title compound, [Cu(C(8)H(7)O(2))(NO(3))(C(10)H(8)N(2))], the Cu(II) ion is five-coordinate in a distorted square-pyramidal geometry. The basal positions are occupied by two N atoms from a 2,2'-bipyridine ligand and two O atoms from the 2-acetyl-phenolate anion. The axial position is occupied by one O atom of a nitrate anion. In the bipyridine ligand, the two pyridine rings are slightly twisted by an angle of 3.5 (1)°. The crystal structure is stabilized by C-H⋯O hydrogen bonds.

catena-Poly[[disilver(I)(Ag-Ag)-bis[mu-1,1'-(butane-1,4-diyl)diimidazole-kappa2N(3):N3']] bis(perchlorate)]: a double helix stabilized by ligand-unsupported argentophilic interactions.

The title compound, {[Ag(2)(C(10)H(14)N(4))(2)](ClO(4))(2)}(n), is a one-dimensional coordination polymer formed by Ag(I) atoms linearly bridged by 1,1'-(butane-1,4-diyl)diimidazole molecules. The chains have a helical arrangement and pairs of chains are held together by the rarely reported ligand-unsupported Ag-Ag interaction [2.966 (1) A], which results in a double-helix structure. The double helix contains twisted 24-membered metallomacrocycles, which are composed of four Ag atoms and two ligands. The Ag atoms lie on twofold axes.

[Studies on the interaction between thionine and deoxyribo-nucleic acid by ethidium bromide probe].

The interaction between thionine and deoxyribonucleic acid was studied with ethidium bromide probe in Tris-HCl buffer solution at pH 7.4 by fluorescence spectra, electronic absorption spectra, and resonance light scattering spectra. From the obtained results, it was found obviously that the planar structure of thionine can be intercalated into the stacked base pairs of DNA, which is the major controlling factor. The binding constant was found to be 1.0 x 10(5) L x mol(-1).