Structural Evolution of Giant Polyoxometalate: From "Keplerate" to "Lantern" Type Mo132 for Improved Oxidation Catalysis

Abstract

Structural variants of high-nuclearity clusters are extremely important for their modular assembly study and functional expansion, yet the synthesis of such giant structural variants remains a great challenge. Herein, we prepared a lantern-type giant polymolybdate cluster (L-Mo₁₃₂ ) containing equal metal nuclearity with the famous Keplerate type Mo₁₃₂ (K-Mo₁₃₂ ). The skeleton of L-Mo₁₃₂ features a rare truncated rhombic triacontrahedron, which is totally different with the truncated icosahedral K-Mo₁₃₂ . To the best of our knowledge, this is the first time to observe such structural variants in high-nuclearity cluster built up of more than 100 metal atoms. Scanning transmission electron microscopy reveals that L-Mo₁₃₂ has good stability. More importantly, because the pentagonal [Mo₆ O₂₇ ]^n- building blocks in L-Mo₁₃₂ are concave instead of convex in the outer face, it contains multiple terminal coordinated water molecules on its outer surface, which make it expose more active metal sites to display superior phenol oxidation performance, which is more higher than that of K-Mo₁₃₂ coordinated in M=O bonds on the outer surface.

Keywords: Phenol Oxidation; Polyoxometalate; Structural Variants.