Synthesis, Crystal Structure and Electrochemical Properties of a New Adduct of Benzo-15-crown-5 and H 3 PMo 12 O 40

A new crown ether-POM (POM = polyoxometalate) adduct with the molecular formula [(C 14 - H 20 O 5 ) 4 (H 3 O) 3 ]PMo 12 O 40 ・ 0.5CH 3 CN (1) was isolated from the mixed solvent of acetonitrile and methanol. The adduct is constructed from Keggin [PMo 12 O 40 ] 3− anions and [(C 14 H 20 O 5 ) - (H 3 O + )] and [(C 14 H 20 O 5 ) 2 (H 3 O + )] cations via electrostatic and hydrogen bonding interactions. The supramolecular interactions combine the crown ether with oxonium ions. In the [(C 14 H 20 O 5 ) - (H 3 O + )] moieties, the oxonium ions reside out of the planes defined by the oxygen atoms of the crown ether. The [(C 14 H 20 O 5 ) 2 (H 3 O + )] moieties exhibit a sandwich structure. There exist hydrogen bonds between the oxonium ions of the [(C 14 H 20 O 5 )(H 3 O)] + cations and the acetonitrile molecules and the terminal and bridging oxygen atoms of the [PMo 12 O 40 ] 3− anions. The adduct has been used as a bulk-modifier to fabricate a chemically modified carbon paste electrode (MCPE), which displays well-defined cyclic voltammograms with three reversible two-electron redox couples in acidic aqueous solution, and electrocatalytic activities towards the reduction of H 2 O 2 and NO 2− .