A lanthanide–tellurium heterometal encapsulated sandwich-type heteropolyoxoniobate with a 3D pcu-type hydrogen-bonded network

A 3D Eu-incorporated niobictellurate supramolecular framework with pcu topology is constructed from a sandwich-type cluster [Ln(H 2 O) 3 Te 6 Nb 18 O 64 (OH) 4 ] 15− and copper–amine complexes with proton conduction and water vapor adsorption properties.