Imparting Water Solubility and Aqueous Electrochemical Activity to Ferrocene upon Confinement.

Electrocatalytic processes underpin technological advances in areas ranging from energy conversion and storage to electrosynthesis of fine and commodity chemicals. Catalyst confinement is an attractive avenue to gain control over activity and selectivity, as well as to tailor solubility or decrease deactivation. The use of supramolecular materials as hosts to confine and stabilize electroactive complexes would be an exciting prospect. Here we report the impact of confinement on the solubility and electrochemical properties of ubiquitous electrochemical probe ferrocene. The notorious water insolubility of ferrocene is overcome through confinement within a Ga4L6 supramolecular cage, and the new host-guest complex not only retains the electroactivity of the incorporated ferrocene molecule but also decreases the oxidation potential of ferrocene by 200 mV, rendering it easier to oxidize. In the context of an electrocatalytic oxidation, this would translate to unlocking activity in a green solvent while reducing the overpotential for catalysis. This work serves as a proof-of-concept demonstration of the potential of supramolecular coordination cages as confinement vessels for molecular electrocatalysts.