Bis(8-hy-droxy-2-methyl-quinolinium) bis-(pyridine-2,6-dicarboxyl-ato)-nickelate(II) methanol monosolvate monohydrate.

In the title compound, (C(10)H(10)NO)(2)[Ni(C(7)H(3)NO(4))(2)]·CH(3)OH·H(2)O, the coordination geometry of the Ni(II) atom can be described as distorted octa-hedral. In the crystal, noncovalent inter-actions play an important role in the stabilization of the structure, involving O-H⋯O, N-H⋯O and weak C-H⋯O hydrogen bonds and π-π stacking inter-actions between the pyridine rings of the pyridine-2,6-dicarboxyl-ate ligands [centroid-centroid distance = 3.7138 (15) Å] and between the 8-hy-droxy-2-methyl-quinolinium cations [centroid-centroid distances = 3.

Tetra-kis{4-[(2H-tetra-zol-5-yl)meth-yl]morpholin-4-ium} dodeca-tungstosilicate hexa-hydrate.

The crystal structure of the title compound, (C(6)H(12)N(5)O)(4)[W(12)(SiO(4))O(36)]·6H(2)O, consists of an α-Keggin-type [W(12)(SiO(4))O(36)](4-) polyoxidoanion, four [(2H-tetra-zol-5-yl)meth-yl]morpholinium cations and six uncoordinated water mol-ecules. In the cations, the morpholine rings display chair conformations. Extensive N-H⋯O, N-H⋯N, O-H⋯O and O-H⋯N hydrogen bonds are present in the crystal structure.

Bis(8-hy-droxy-2-methyl-quinolinium) bis-(pyridine-2,6-dicarboxyl-ato)cuprate(II) methanol monosolvate monohydrate.

The title compound, (C(10)H(10)NO)(2)[Cu(C(7)H(3)NO(4))(2)]·CH(3)OH·H(2)O was prepared by the reaction of copper(II) nitrate hexa-hydrate, 8-hy-droxy-2-methyl-quinoline, and pyridine-2,6-dicarb-oxy-lic acid in a 1:2:2 molar ratio in an aqueous solution. The geometry of the resulting CuN(2)O(4) coordination can be described as distorted octa-hedral. In the crystal, there are several inter-molecular O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds.

Tris{4-[(2H-tetra-zol-5-yl)meth-yl]morpholinium} dodeca-tungstophosphate hexa-hydrate.

The title heteropolyoxidotungstate-based inorganic-organic hybrid material, (C(6)H(12)N(5)O)(3)[W(12)(PO(4))O(36)]·6H(2)O, consists of one α-Keggin-type [W(12)(PO(4))O(36)](3-) polyoxidometalate anion (POM), three crystallographically independent 4-[(2H-tetra-zol-5-yl)meth-yl]morpholinium cations and six water mol-ecules of crystallization. The morpholine ring of the cation adopts a chair conformation. The anion shows characteristic features with respect to bond lengths and angles.