Redox reactions between molecular oxygen and tetrachlorohydroquinone at the water∣1,2-dichloroethane interface

Potential-Modulated Ion Distributions in the Back-to-Back Electrical Double Layers at a Polarised Liquid|Liquid Interface Regulate the Kinetics of Interfacial Electron Transfer

Biphasic interfacial electron transfer (IET) reactions at polarisable liquid|liquid (L|L) interfaces underpin new approaches to electrosynthesis, redox electrocatalysis, bioelectrochemistry and artificial photosynthesis. Herein, using cyclic and alternating current voltammetry, we demonstrate that under certain experimental conditions, the biphasic 2-electron O2 reduction reaction can proceed by single-step IET between a reductant in the organic phase, decamethylferrocene, and interfacial protons in the presence of O2. Using this biphasic system, we demonstrate that the applied interfacial Galvani potential differenceΔ o w φ provides no direct driving force to realise a thermodynamically uphill biphasic IET reaction in the mixed solvent region. We show that the onset potential for a biphasic single-step IET reaction does not correlate with the thermodynamically predicted standard Galvani IET potential and is instead closely correlated with the potential of zero charge at a polarised L|L interface. We outline that the appliedΔ o w φ required to modulate the interfacial ion distributions, and thus kinetics of IET, must be optimised to ensure that the aqueous and organic redox species are present in substantial concentrations at the L|L interface simultaneously in order to react.

Molecular oxygen reduction catalyzed by a highly oxidative resistant complex of cobalt–hydrazone at the liquid/liquid interface

Syntheses, structure and spectroscopic studies of a new cobalt complex with a hydrazine ligand. The first report on a highly oxidative resistant complex in the ORR electrocatalysis at the liquid–liquid interface.

Surprising acidity of hydrated lithium cations in organic solvents

The surprising acidity of hydrated lithium cations was found to have a significant role in catalyzing many chemical reactions.

Electrochemical investigation of dopamine at the water/1,2-dichloroethane interface

Dopamine is an important neurotransmitter in mammalian central and peripheral nervous systems and is also a medicament to cure some neuropsychosis. In this work, ion transfer (IT), facilitated ion transfer (FIT) of protonated dopamine, and electron transfer (ET) between dopamine and ferrocene are investigated at the water/1,2-dichloroethane (W/DCE) interface. The IT and FIT reactions of protonated dopamine can be observed simultaneously within the same potential window. The experimental results demonstrate that dibenzo-18-crown-6, dibenzo-24-crown-8, and benzo-15-crown-5 work well with the protonated dopamine. The amperometric detection of dopamine based on either the IT or the FIT of protonated dopamine can get rid of the interference of ascorbic acid, and the lowest concentration that can be determined is approximately 0.05 microM by differential pulse voltammetry. For the ET reaction, its kinetics can be evaluated by scanning electrochemical microscopy, and the results show that the relationship between rate constants and driving force at the unmodified W/DCE interface obeys the Butler-Volmer equation in a rather wide potential region. When the W/DCE interface is modified by egg lecithin, the ET rate constants decrease with increasing concentration of egg lecithin, which indicates that egg lecithin hinders the ET reaction. When the driving force is increased to a certain degree, the linear relationship between ET rate constants and the driving force is distorted. These results will be helpful to understand both the pharmacodynamics and the neural signal transmission mechanism of dopamine at biological membranes and also provide a novel way to detect dopamine.

Square-Wave Voltammetry of Decamethylferrocene at the Three-Phase Junction Organic Liquid/Aqueous Solution/Graphite

Drops of nitrobenzene and 1,2-dichloroethane with 0.1 M decamethylferrocene (dmfc) are attached to the surface of a paraffin-impregnated graphite electrode and immersed into various aqueous electrolytes. The oxidation of dmfc and the reduction of dmfc+ cation are enabled by simultaneous transfers of anions between the aqueous electrolyte and the organic solvents. Square-wave voltammetry of this reaction is reported. A linear relationship was observed between the peak potentials of dmfc and the standard Galvani potential differences of the anions. The influence of the anion concentration on this relation is explained.