A tetrahedron-shaped polyoxoantimotungstate encapsulating a hexanuclear octahedral lanthanide-oxo cluster for an amperometric bromate sensor.

An inorganic hexalanthanide-oxo-cluster-encapsulated antimotungstate, KNaH[Nd(OH)(HO)(B-α-SbWO)]·67HO (1), has been successfully synthesized by a facile one-step hydrothermal reaction method. The tetrahedron-shaped two-shell {Nd(OH)(HO)(B-α-SbWO)}(1a) polyanion is composed of a novel pure lanthanide-oxo {Nd(μ-OH)(HO)} octahedron and {(B-α-SbWO)} tetrahedron. After being effectively loaded onto a glassy carbon electrode (GCE) by electrostatic adsorption using polydiallyldimethyl ammonium chloride (PDDA)-functionalized multi-walled carbon nanotubes (MWCNTs), compound 1 exhibits electrochemical activity for the reduction of bromate ions with good selectivity, a high sensitivity of 186 μA mM and a detection limit that has reached 1.9 μM. To the best of our knowledge, this is the first example of an amperometric bromate sensor based on Ln-containing antimotungstates, which will provide new materials for electrochemical sensors.