Reusable and Highly Active Copper-Based Lacunary-type Polyoxometalate (LPMo-Cu) as an Effective Catalyst for Nitroarene Reduction in Aqueous Solution

Lacunary polyoxometalates (LPOMs),a class of anionic metal oxideclusters, are promising materials as catalysts, photocatalysts, andelectrocatalysts. Designing and functionalizing this type of compoundare key factors for the discovery and development of novel materials.Herein, a new lacunary polyoxometalate-based compound was designedas a heterogeneous catalyst, prepared through functionalization ofa lacunary Keggin-type polyoxometalate, i.e., [PMo11O39](7-), with 3-aminopropyltrimethoxysilane(APTS) and 2-pyridine carboxaldehyde. Subsequent reactions of thiscompound with Cu2+ ions led to the desired catalyst, LPMo-Cu.The catalytic activity of the obtained LPMo-Cu was examined in nitroarenereduction using sodium borohydride as a reducing agent in aqueoussolution. It was specified that the synthesized LPMo-Cu exhibits highcatalytic efficiency in the reduction of a wide variety of nitroarenesin a short time (5 min). Furthermore, the stability and recoverabilityof the prepared material were proved as a result of four consecutivereduction cycles without a significant decrease in its efficiency.