Polyoxometalate aerogels formed by organofunctionalized Anderson polyoxometalates as low molecular weight gelators

Abstract

Polyoxometalate-based aerogels, built through supramolecular interactions and metal coordination, have the potential to expand the field of smart materials. Here, the first example of the conversion of an Anderson-polyoxometalate-based organogel into a catalytically active aerogel is reported. The polyoxometalate organogel is formed by the reaction of ZnCl2 with the TRIS-functionalized Anderson polyoxometalate (nBu4N)3[MnMo6O18{(OCH2)3CNH2}2]. Conversion of the organogel into the aerogel is achieved by a scalable freeze-drying procedure. A range of experimental methods are employed to follow the conversion of the POM into the organogel and aerogel, and insights into the role of the polyoxometalate, the metal salt, and the solvent are reported. The catalytic activity of the aerogel for selective alcohol oxidations (model compounds: benzyl alcohol, furfuryl alcohol, octanol) is reported together with initial recyclability studies. A conversion yield of 30% for benzaldehyde is achieved using aerogel as a catalyst. The study opens the door to (multi-)functional polyoxometalate-based aerogels for sorption, separation, catalysis, and energy technologies.