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

Abstract

A new complex of Co(III) using an oxidative stable hydrazone ligand, CoL, was synthesized and characterized by elemental analysis, spectroscopic methods and single crystal X-ray analysis where HL is bis-[(E)-N'-(phenyl(pyridin-2-yl)methylene)]carbohydrazide. X-ray analysis revealed that the complex is mononuclear and the coordination environment around the Co(III) core is trans-[CoN4Cl2]. The catalytic activity of the complex in the oxygen reduction reaction was investigated. The complex is a highly oxidative resistant cobalt-hydrazone which can efficiently catalyze the reduction of oxygen (O2) by a weak electron donor ferrocene, (Fc), at the polarized water/1,2-dichloroethane (DCE) interface. Oxygen reduction is coupled with proton transfer from water to the organic phase to form hydrogen peroxide, which is extracted into the aqueous phase.

H2O2 Generation at a Carbon‐Paste Electrode with Decamethylferrocene in 2‐Nitrophenyloctyl Ether as a Binder: Catalytic Effect of MoS2 Particles

“…For aC PE prepared by using DMFc in NPOE, with no potentiala ppliedt oi t, the flux of H 2 O 2 generated at the CPE surface was approximately 0.46 pmol cm À2 s À1 .T his flux is almost seven times smaller than that seen at the 1,2-dichloroethane/ water interface, [12] not restricted by carbon particles. No H 2 O 2 was detected when the electron donor (DMFc) was absent from the carbon paste (violet curve in Figure S4), which confirms its role in the two-phase Reaction (2). However,w hen the CPE potential was low enough to regenerate the electron donor from DMFc + formed in Reaction (2), the flux of H 2 O 2 Figure 6.…”

“…Regarding the two-phase reaction, the most important conclusion herei st hat the anion-insertion mechanism [Eq. (4)] dominates in the presence of perchlorate and the oxidized form of the electron donor does not transfer to the aqueous phase [Reaction (2)]. T he presence of MoS 2 clearly does not affect this mechanism.…”

“…Formation of simple chemicals, like hydrogen peroxide, at soft interfaces between two immiscible electrolyte solutions (ITIES) has gained an increasing attention over the last several years . This is because these reactions can be driven by polarization of the liquid–liquid interface.…”

“…Formation of simple chemicals, like hydrogen peroxide,a ts oft interfaces between two immiscible electrolyte solutions( ITIES) has gained an increasing attentiono ver the last several years. [1][2][3] This is because these reactions can be driven by polarization of the liquid-liquid interface. In practice, this can be done by applyinge xternal voltage or by appropriate selection of electrolytes with ac ommon ion in both liquid phases.…”

“…The anodic peak connected with oxidation of DMFc [Reaction (5)] is less developed in the presence of O 2 in aqueous electrolyte. Al arger cathodic current compared with the anodic one indicates consumption of the electron donori nc atalytic Reaction (2). [41] The cathodic peak current is clearly higher than the anodic one.…”