Two new organic-inorganic supramolecular hybrids templated by the Wells-Dawson polyoxometalates

Two new supramolecular compounds based on the Wells-Dawson polyoxometalate, [Cu(Hpbi)2]4[P2W18O62]2 (1) and (H2bbi)4[Cu2(bbi)(Hbbi)2][P2W18O62]2 (2) (pbi = 1,1′-(1,3-propanediyl)bis(imidazole), bbi = 1,1′-(1,4-butanediyl)bis(imidazole)), were hydrothermally synthesized and characterized by elemental analyses, IR spectroscopy, thermogravimetric analyses, and single X-ray diffraction. The [P2W18O62]6− polyanions in both compounds play the template role inducing the metal-organic coordination polymers to array around them. The polymers form 3D supramolecular frameworks with different voids in which the polyanions reside. The difference should be attributed to the different lengths of the two organic ligands. In addition, the electrochemistry properties of the two compounds were studied, which indicates that the supramolecular compounds keep the redox properties of their parent polyanions and exhibit the electrocatalytic activities toward the reduction of bromate and nitrite.