(758i) Redox-Active Organometallic Polymers for Small Molecule Separations
For the anode, investigations with poly(vinyl)ferrocene (PVF) have previously shown significant ion-selective binding properties of these redox-electrodes towards various organic functional groups, especially carboxylates. During oxidation, poly(vinyl)ferrocenium specifically binds to carboxylates with >300-fold separation factors and >250 mg/g adsorption capacities.2 We show that through organic modification of the ligand, these anion-metallocene interactions can be enhanced even further to achieve fine chemical separations between very similar, substituted benzoic acids, through modulation of the redox-properties. In parallel, at the cathode, cobalt-based polymers [based on Cobaltocenium (PMAECoCp2) and (Î·5-cyclopentadienyl)-cobalt(Î·4-tetraphenyl-cyclobutadiene) (PCpCoCb)Â complexes] are utilized to asymmetrically couple with the anode ferrocene to enhance electrochemical performance.3 In particular, during reduction PCoCpCb can become negatively charged and selectively remove a range of cations, including heavy metals and aromatic organics. Finally, we show recent work on how these tandem asymmetric systems can be used for efficient bulk deionization.
Thus, whether used individually or in tandem, properly designed redox-active polymers have shown to be efficient materials for achieving selective ion-binding in both aqueous and organic media, at moderate to low voltage windows - pointing to their unique capability as a bridge between energy and environmental applications.
(1) Su, X.; Hatton, T. A. Advances in Colloid and Interface Science 2016. 10.1016/j.cis.2016.09.001.
(2) Su, X.; Kulik, H. J.; Jamison, T. F.; Hatton, T. A. Advanced Functional Materials 2016, 26, 3394.
(3) Su, X.; Tan, K. J.; Elbert, J.; Ruttiger, C.; Gallei, M.; Jamison, T. F.; Hatton, T. A. Energy & Environmental Science 2017, ASAP article.