Two new extended frameworks constructed from the sandwiching polytungstoarsenate clusters

Abstract

Two new extended frameworks based on two different sandwich-type polytungstoarsenates have been synthesized under routine conditions. The reaction of Na 9[As IIIW 9O 33]·19.5H 2O, MnSO 4·H 2O and citric acid in a weak acidic aqueous solution at pH = 4.23 led to the isolation of a new extended sandwich-type compound {K 3Na 8[{Mn II(H 2O)} 2.5{(WO)(H 2O)} 0.5(AsW 9O 33) 2]·12.5H 2O} n ( 1). In compound 1, each sandwiching polyoxoanion [{Mn II(H 2O)} 2.5{(WO)(H 2O)} 0.5(AsW 9O 33) 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 Na 8[HAsW 9O 34]·11H 2O, CeCl 3·7H 2O and hexamethylenetetramine in an aqueous solution with pH = 5.07 resulted in the obtainment of a polytungstoarsenate-based extended compound [HMTA–CH 3] 2[HMTA]K 2Na 7[Ce(AsW 11O 39) 2]·19H 2O( 2) (HMTA–CH 3 = methyl-hexamethylenetetraamine; HMTA = hexamethylenetetraamine). In 2, the polyoxoanions [Ce(AsW 11O 39) 2] 11− construct a new extended structure through coordinating to the {KO 5(H 2O)[HMTA–CH 3]} and {KO 4(H 2O) 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.