A uranium-bridged dimeric Keggin-type polyoxometalate and its proton conductive properties

A novel dimeric structure based on trilacunary Keggin-type [SbW9O33]9- was synthesized and comprehensively characterized. Different from the conventional dimeric structures, the compound (NH4)10[(SbW9O33)2(UO2)2(H2O)2(SbOH)2]<middle dot>7H2O ({U2Sb4}) features two additional Sb3+ cations. The successful synthesis of {U2Sb4} reveals the significant role of heteroatoms in structural modulation. The dimer forms a hydrogen-bonded network with water molecules and NH4+ and is therefore expected to exhibit remarkable proton conductivity. Proton conduction studies revealed that {U2Sb4} was a temperature and humidity-dependent proton conductor with conductivity reaching up to 2.50 x 10-2 S cm-1 at 85 degrees C and 85% RH. A novel dimeric structure based on trilacunary Keggin-type [SbW9O33]9- was synthesized, featuring two additional Sb3+ cations. This compound exhibits significant proton conductivity, reaching up to 2.50 x 10-2 S cm-1 at 85 degrees C and 85% RH.