Anion transfer for highly hydrophilic phosphate and hydroxide anions into a water-immiscible organic phase, 3-(4-phenylpropyl)-pyridine (or PPP), is driven with the tetraphenylporphyrinato manganese(II/III) (or TPPMn) redox system and facilitated with a hydrophobic oil-based boronic acid ((3-(1,3-dioxo-6-propylamino-1H-benzo[de]isoquinolin-2(3 H)-yl)phenyl)boronic acid). Both 1) experiments with random arrays of microdroplets (transient) and 2) experiments in a gold–gold dual-plate oil-filled microtrench generator-collector configuration (approaching steady state), show that phosphate transfer is facilitated by boronic acid. At pH 7.5 a switch in mechanism occurs from phosphate transfer to hydroxide transfer. Accelerated charge transport is observed lateral to the oil|water interface. Improved boronic acid facilitators and nanotrench electrodes are discussed in terms of future feasibility for phosphate sensing applications.
Li, M., Lewis, G. E. M., James, T. D., Long, Y., Kasprzyk-hordern, B., Mitchels, J. M., & Marken, F. (2014). Oil|Water Interfacial Phosphate Transfer Facilitated by Boronic Acid: Observation of Unusually Fast Oil|Water Lateral Charge Transport. ChemElectroChem, 1(10), 1604-1646. https://doi.org/10.1002/celc.201402181