catena-Poly[[[tetra-aqua-zinc(II)]-µ-4,4'-bipyridine-κN:N'] benzene-1,4-di-carboxyl-ate].

In the title compound, {[Zn(C(10)H(8)N(2))(H(2)O)(4)](C(8)H(4)O(4))}(n), the Zn(II) atoms, lying on a twofold rotation axis, are bridged by 4,4'-bipyridine ligands, resulting in a linear chain along the b axis. In the chain, the Zn(II) atom adopts a slightly distorted octa-hedral coordination geometry involving four water mol-ecules at the equatorial positions. The noncoordinated benzene-1,4-dicarboxyl-ate anion, which is also located on a twofold rotation axis, bridges adjacent chains through O-H⋯O hydrogen bonds, forming a three-dimensional supra-molecular network.

1,1'-Dimethyl-4,4'-(propane-1,3-di-yl)dipyridinium tetra-bromidocadmate(II).

In the cation of the title compound, (C(15)H(20)N(2))[CdBr(4)], the dihedral angle between the two pyridine rings is 70.85 (5)°. An inter-molecular π-π inter-action between the pyridine rings [centroid-centroid distance = 3.900 (4) Å] is observed. The Cd(II) atom has a distorted tetra-hedral coordination.

5-Amino-3-(4-pyrid-yl)isoxazole.

In the title compound, C(8)H(7)N(3)O, there are two independent mol-ecules in the asymmetric unit, in which the angles between the pyridine ring and the isoxazole ring are 35.8 (6) and 10.6 (2)°. The crystal packing is stabilized by N-H⋯N hydrogen bonds, which result in the mol-ecules forming a two-dimensional supra-molecular layer.

1,1'-Dimethyl-4,4'-bipyridinium bis-(tetra-fluorido-borate).

In the title compound, C(12)H(14)N(2) (2+)·2BF(4) (-), the cation has a centre of symmetry at the mid-point of the central C-C bond. π-π inter-actions, with a shortest atom-to-atom distance of 3.757 (4) Å, extend the crystal structure into a one-dimensional supra-molecular chain.

Synthesis and characterization of chitosan/ZnO nanoparticle composite membranes.

Novel chitosan/ZnO nanoparticle (CS/nano-ZnO) composite membranes were prepared via the method of sol-cast transformation and studied by UV-vis absorption spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray fluorescence spectrometry (EDX). The characterization revealed that ZnO nanoparticles dispersed homogeneously within the chitosan matrix. The mechanical and antibacterial properties of the product were investigated. The results showed that the ZnO content had an effect on the mechanical properties of CS/nano-ZnO composite membranes, and that the antibacterial activities of CS membranes for Bacillus subtilis, Escherichia coli, and Staphylococcus aureus were enhanced by the incorporation of ZnO. Further, CS/nano-ZnO composite membranes with 6-10 wt% ZnO exhibited high antibacterial activities.