Electrochemistry of ferrocene in acetonitrile

Blatter-type radicals as polarizing agents for electrochemical overhauser dynamic nuclear polarization

Overhauser dynamic nuclear polarization (O-DNP) refers to a microwave-assisted process where an unpaired electron's (e.g. a radical) spin polarization is transferred to surrounding nuclei in solution, thus increasing the nuclear magnetic resonance (NMR) signal intensity of a given substance by several orders of magnitude. The presence of the unpaired electrons, which induces relaxation of the resulting hyperpolarized state when the radiation is halted, can be avoided by electrochemically removing the radicals on demand. We report the use of Blatter-type (benzo[e][1,2,4]triazinyl) radicals as polarizing agents, potentially opening the way to highly tunable radicals for electrochemical DNP.

Use of the ferrocene oxidation process to provide both reference electrode potential calibration and a simple measurement (via semiintegration) of the uncompensated resistance in cyclic voltammetric studies in high-resistance organic solvents

Because of its presumed ideal reversible behavior, the oxidation of ferrocene is widely used in cyclic voltammetric studies in highly resistive organic solvents as a means of reference electrode potential calibration. In this study, it is shown that a good estimate of the uncompensated resistance value, needed for reference potential correction and also frequently an input parameter in simulation of the theory, can be obtained simultaneously with the ferrocene reference potential measurement using a simple analysis based on the semiintegral. Application to cyclic voltammetric oxidation of ferrocene in dichloromethane (0.1 M NBu4PF6), under conditions where uncompensated resistances of approximately 2.5 komega are encountered, is used to illustrate the fidelity of the semiintegral method of analysis. Inclusion of this estimated resistance value as the input parameter in a commercially available digital simulation package confirms that the oxidation of ferrocene in dichloromethane represents a close-to-ideal diffusion-controlled reversible process. However, use of the semiintegral method of data analysis also enables detection of subtle forms of nonideality encountered with the ferrocene oxidation process in other media where kinetically controlled adsorption of the ferricenium cation may occur.