Two new extended frameworks constructed from the sandwiching polytungstoarsenate clusters

Two new extended frameworks based on two different sandwich-type polytungstoarsenates have been synthesized under routine conditions. The reaction of Na₉As^IIIW₉O₃₃]·19.5H₂O, MnSO₄·H₂O and citric acid in a weak acidic aqueous solution at pH = 4.23 led to the isolation of a new extended sandwich-type compound {K₃Na₈{Mn^II(H₂O)}_2.5{(WO)(H₂O)}_0.5(AsW₉O₃₃)₂]·12.5H₂O}_n (1). In compound 1, each sandwiching polyoxoanion {Mn^II(H₂O)}_2.5{(WO)(H₂O)}_0.5(AsW₉O₃₃)₂]¹¹⁻ acts as a quadridentate ligand to connect with four neighbors via the mode of {W-O-Mn}, finally leading to an interesting 2D network. The reaction of Na₈HAsW₉O₃₄]·11H₂O, CeCl₃·7H₂O and hexamethylenetetramine in an aqueous solution with pH = 5.07 resulted in the obtainment of a polytungstoarsenate-based extended compound HMTA-CH₃]₂HMTA]K₂Na₇Ce(AsW₁₁O₃₉)₂]·19H₂O(2) (HMTA-CH₃ = methyl-hexamethylenetetraamine; HMTA = hexamethylenetetraamine). In 2, the polyoxoanions Ce(AsW₁₁O₃₉)₂]¹¹⁻ construct a new extended structure through coordinating to the {KO₅(H₂O)HMTA-CH₃]} and {KO₄(H₂O)₂HMTA]} units. The two compounds are characterized by elemental analyses, IR, the diffuse reflectance UV-Vis spectra, PXRD and TG analyses. The electrochemical and electrocatalytical properties of 1 and 2, as well as the fluorescent property of 2 were also investigated.