A new polyoxometalate-based silver-organic framework as environmental-friendly catalyst for solvent-free cyanosilylation of aldehydes

A new polyoxometalate-based silver-organic framework Ag4(imbta)4(PWVWVI11O40) (1) (imbta=1-imidazol-1-ylmethyl-1H-benzotriazole) was synthesized as heterogeneous catalysts for cyanosilylation, and characterized by infrared spectroscopy, elemental analysis, single-crystal X-ray diffraction and X-ray photoemission spectra. The results of single crystal X-ray indicate that in compound 1, Ag ions, imbta ligands and PW12O403- construct a 2D layers by covalent bonds. The adjacent 2D layers are further connected together through numerous π‧‧‧π interactions and C–H‧‧‧O hydrogen bonding interactions to achieve a 3D supramolecular architecture. More importantly, compound 1 is able to act as a highly efficient heterogeneous Lewis acid-base catalyst for cyanosilylation of various aldehydes at room temperature under solvent-free condition. The conversion of anisaldehyde to the product of cyanohydrin trimethylsilyl ether reaches up to 99.9% within 4 h by catalyzing of compound 1. Also, it is observed that there is no obvious decrease of catalytic activity after three cycles. Therefore, the compound 1 has significant potential as environmental-friendly catalyst for widely practical application in cyanosilylation reactions.