Voltammetric characterisation of diferrocenylborinic acid in organic solution and in aqueous media when immobilised into a titanate nanosheet film

Diferrocenylborinic acid (Fc2BOH, 1) has been synthesized in good yield via an improved synthetic path. Characterisation by nuclear magnetic resonance (NMR), mass spectrometry (HRMS), infrared spectroscopy (FTIR), X-ray crystallography, and by electrochemical methods reveal two one-electron oxidation processes for the two electronically coupled ferrocenyl moieties. The oxidation of 1 dissolved in organic media is contrasted to the oxidation of 1 in aqueous environments (by incorporation of 1 into a lamellar film of 2D titanate nanosheets on a glassy carbon electrode). Data from cyclic voltammetry and from square wave voltammetry suggest that the bridging boron can bind to nucleophiles (hydroxide, fluoride) upon oxidation of the ferrocenyl groups. A multi-pathway ECE reaction scheme is proposed. Potential applications in sensing are discussed.