Recent advances on high-nuclear polyoxometalate clusters

The design and construction of high-nuclear polyoxometalate (POM) clusters remain a severe challenge, but attract significant interest on account of their impressive structural versatility and outstanding properties in nanosized dimensions. With continuous exploration, diverse synthetic strategies have been developed that open multiple windows for constructing and engineering abundant high-nuclear POM species with function-oriented applications. Remarkably, the unique behaviors of Mo, W, V, Nb and Ta have demonstrated the promise of POMs in fabricating distinct architectures (from giant molecular metal oxides to metal–organic polyhedra) and applications (from catalysis, electrode materials, proton conductivity, magnetism, luminescence to molecular recognition and gas separation, etc.). This review summarizes recent advances on high-nuclear POM clusters, highlighting synthetic strategies, structural classifications and relevant applications in different areas. Furthermore, challenges and prospects of high-nuclear POM clusters are presented.