catena-Poly[[nickel(II)-μ-1,3-dimethyl-2,6-dioxo-7H-purinato-κ2 N 7:N 9] hydroxide]

The title complex, {[Ni(C7H7N4O2)]OH}n, has been prepared through hydro­thermal synthesis. The asymmetric unit contains one [Ni(TH)]+ cation (TH is the theophylline anion) and one hydroxide anion. The Ni2+ ion is coordinated by two N atoms from two neighboring theophylline anions. The alternating linkage of the Ni2+ cation and theophylline anion results in a one-dimensional chain along the [010] direction. Intermolec­ular O—H⋯O hydrogen bonds are present n the crystal structure

Controlling the Intrinsic Josephson Junction Number in a Bi2Sr2CaCu2O8+δ\mathbf{Bi_2Sr_2CaCu_2O_{8+\delta}} Mesa

In fabricating $\mathrm{Bi_2Sr_2CaCu_2O_{8+\delta}}$ intrinsic Josephson junctions in 4-terminal mesa structures, we modify the conventional fabrication process by markedly reducing the etching rates of argon ion milling. As a result, the junction number in a stack can be controlled quite satisfactorily as long as we carefully adjust those factors such as the etching time and the thickness of the evaporated layers. The error in the junction number is within $\pm 1$. By additional ion etching if necessary, we can controllably decrease the junction number to a rather small value, and even a single intrinsic Josephson junction can be produced.Comment: to bu published in Jpn. J. Appl. Phys., 43(7A) 200

Bis(4,4′-methyl­enedianilinium) naphthalene-1,5-disulfonate dihydrate

The asymmetric unit of the title salt, C13H16N2 2+·C10H6O6S2 2−·2H2O, consists of one dication located on a general position, half each of two centrosymmetric dianions, and two uncoordinated water mol­ecules in general positions. In the dication, the dihedral angle between the benzene rings is 74.67 (6)°. The cations and anions inter­act through N—H⋯O hydrogen bonds. The NH3 + functional groups are also involved in N—H⋯O hydrogen bonds with the water mol­ecules, forming an infinite three-dimensional framework in the crystal structure