catena-Poly[[[diaqua-bis(8-hydroxy-quinoline N-oxide-κO)cobalt(II)]-µ-2,5-dimethyl-pyrazine 1,4-dioxide-κO:O] bis-(perchlorate)].

In the title complex, {[Co(C(6)H(8)N(2)O(2))(C(9)H(7)NO(2))(H(2)O)(2)](ClO(4))(2)}(n), the Co(II) ion lies on an inversion centre and is coordinated in a slightly distorted octa-hedral environment. The 2,5-dimethyl-pyrazine 1,4-dioxide ligand, which also lies on an inversion center, acts as a bridging ligand, linking symmetry-related Co(II) ions [Co⋯Co = 8.669 (3) Å] and forming one-dimensional chains along the b axis. In the crystal structure, these chains are linked by inter-molecular aqua-perchlorate O-H⋯O hydrogen bonds, forming two-dimensional layers which are in turn connected into a three-dimensional network via π-π stacking inter-actions between quinoline rings, with a centroid-centroid distance of 3.580 (3) Å. An intermolecular O-H⋯Cl inter-action is also present.

[Comparative study on trace elements in natural colored cotton and white cotton].

A method was studied for simultaneous determination of multi-elements in natural colored cotton by microwave digestion and ICP-AES. The contents of Ca, Mg, Fe, Cu, Ba, Zn, Al, Sr, Mn and Si in colored and white cotton were determined by this method. The recovery ratio obtained by standard addition method ranged between 93% and 111%, and the relative standard deviation was below 4% (n = 5). The results showed that the contents of Ca, Cu, Zn, Al, Fe, Sr and Si in green and brown cotton are higher than those in white cotton. The data from the study gives some references for further researches on the colored cotton.