Self-assembly of a giant molybdenum titanium-oxo cluster [Mo42Ti12(O2)24] for bifunctional oxidation catalysis

Abstract

The exploration of high-nuclearity molecular molybdenum titanium-oxo clusters (MoTOCs) and their reactivity is a great challenge for polyoxometalate chemistry and materials science. Herein, we report a giant MoTOC [K₈(H₂O)₈][Ti₁₂(O₂)₆(OH)₁₂Mo₄₂O₁₂₄(O₂)₁₈(H₂O)₁₇]·31H₂O (1) by self-assembly of degraded lacunary isopolymolybdate fragments and peroxide-stabilized titanium ions in aqueous solution. Compound 1 features 54 metal centers and a rare pure inorganic triangular prism structure with a size of 1.8 × 1.8 × 1.5 nm³, which is the first and largest water-soluble MoTOC found to date. More importantly, it contains multiple peroxo groups on the surface, which makes it exhibit superior benzyl alcohol/benzaldehyde (photo)catalytic oxidation performance. This work opens an unusual avenue for the synthesis of giant MoTOCs.