Syntheses, crystal structures and electrochemical properties of two new supramolecular compounds based on hexamolybdates and crown ethers

Two new supramolecular compounds based on hexamolybdates and crown ethers, [Na(Benzo-15-crown-5)(H2O)(CH3CN)]2Mo6O191 and [Na(Dicyclohexyl-18-crown-6)]2Mo6O192 have been synthesized and characterized by elemental analysis, IR, TG, single crystal X-ray diffraction and electrochemical analysis. There are dominantly the electrostatic interactions between the crown ether–Na+ complex cations and the Mo6O192− polyanions in the compounds. In 2, the Mo6O192− anions are packed in the AB…AB layers along the c axis and the nearest Ot…Ot distances of neighboring Mo6O192− anions in the A layers are shorter than those in the B layers. The POM–crown ether supramolecular compounds have been used as the bulk-modifier to fabricate the chemically modified carbon paste electrodes (MCPE) successfully. They display well-defined cyclic voltammograms with three two-electron reversible redox couples in acidic aqueous solution, electrocatalytic activities toward the reduction of hydrogen peroxide and good stability due to their insolubility.