Hydrothermal syntheses and structure characteristics of two new supramolecular compounds assembled from octamolybdates and bpy units (bpy = 4,4′-bipyridine)

Two new compounds, (Hbpy)3(bpy)2[K(Mo8O26)]·2H2O (1) and H3(bpy)5[K(Mo8O26)]·H2O(2) (bpy = 4,4′-bipyridine) have been synthesized under hydrothermal condition by using nearly the same starting materials, and characterized by elemental analyses, IR, TGA, XPS and single crystal X-ray diffractions. The crystal structure analyses reveal that the two compounds possess unusual networks constructed from octamolybdates, potassium ions and organic groups. Both 1 and 2 consist of an identical inorganic chain [K(Mo8O26)]n3n-, and they have analogous structures to each other with slightly different packing modes of the organic groups and water molecules and exhibit unusual three-dimensional (3D) supramolecular networks through extensive multi-point C–H⋯O and N–H⋯O hydrogen-bonding interactions.