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 Na9[AsIIIW9O33]·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[{MnII(H2O)}2.5{(WO)(H2O)}0.5(AsW9O33)2]·12.5H2O}n (1). In compound 1, each sandwiching polyoxoanion [{MnII(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 Na8[HAsW9O34]·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]2[HMTA]K2Na7[Ce(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)2[HMTA]} 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.