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

Abstract

An inorganic hexalanthanide-oxo-cluster-encapsulated antimotungstate, K₂Na₃H₄₃[Nd₆(OH)₆(H₂O)₆(B-α-SbW₉O₃₃)₄]₂·67H₂O (1), has been successfully synthesized by a facile one-step hydrothermal reaction method. The tetrahedron-shaped two-shell {Nd₆(OH)₆(H₂O)₆(B-α-SbW₉O₃₃)₄}(1a) polyanion is composed of a novel pure lanthanide-oxo {Nd₆(μ₃-OH)₆(H₂O)₆} octahedron and {(B-α-SbW₉O₃₃)₄} 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⁻¹ 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.