Lanthanide derivatives of Ta/W mixed-addendum POMs as proton-conducting materialsElectronic supplementary information (ESI) available: Experimental procedures, crystallographic structures, FTIR spectroscopy, thermal analyses, PXRD patterns, and proton conductivity measurement for the title compounds. CCDC 1507115-1507117 and 1507119. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7dt00091j

Four lanthanide derivatives of Ta-containing POMs [Ln 3 (H 2 O) 22 ][P 2 W 15 Ta 3 O 62 ]· n H 2 O (Ln = La, 1 ; Ce, 2 ; Pr, 3 ; and Nd, 4 ) were isolated by the self-assembly of Wells-Dawson type Ta/W mixed-addendum POM and lanthanide ions. Compound 1 showed excellent proton conduction performance at high relative humidities (RHs), with conductivity reaching 1.26 × 10 −2 S cm −1 at 95 °C under 98% RH. Four lanthanide derivatives were isolated by the self-assembly of {P 2 W 15 Ta 3 O 62 } and lanthanide ions, which showed good proton conduction performance.