A Supramolecularly Activated Radical Cation for Accelerated Catalytic Oxidation

Abstract

Tuning the activity of radicals is crucial for radical reactions and radical-based materials. Herein, we report a supramolecular strategy to accelerate the Fenton reaction through the construction of supramolecularly activated radical cations. As a proof of the concept, cucurbit[7]uril (CB[7]) was introduced, through host-guest interactions, onto each side of a derivative of 1,4-diketopyrrolo[3,4-c]pyrrole (DPP), a model dye for Fenton oxidation. The DPP radical cation, the key intermediate in the oxidation process, was activated by the electrostatically negative carbonyl groups of CB[7]. The activation induced a drastic decrease in the apparent activation energy and greatly increased the reaction rate. This facile supramolecular strategy is a promising method for promoting radical reactions. It may also open up a new route for the catalytic oxidation of organic pollutants for water purification and widen the realm of supramolecular catalysis.

Tuning the stability of organic radicals: from covalent approaches to non-covalent approaches

“…67,68 In contrast, for radical cations, the effect of the electrostatic interaction of cucurbituril on the stability of radicals can be reversed. We reported that the radical cation of a derivative of 1,4-diketopyrrolo-[3,4-c]-pyrroles (DPPc + ) could be activated by cucurbiturils 69,70 (Fig. 14).…”

A supramolecular radical cation: folding-enhanced electrostatic effect for promoting radical-mediated oxidation

“…Recently, we demonstrated that the electrostatic effect of cucurbit[7]uril (CB[7]) can be used for activating radical cations. 2 One might wonder if a highly activated supramolecular radical cation could be constructed by amplifying the electrostatic effect of cucurbituril. However, in the case of CB[7], this electrostatic effect is hard to further improve due to the binding mode between CB[7] and guests.…”

A Stable Room‐Temperature Luminescent Biphenylmethyl Radical

“…Because of the open-shell electronic structures,o rganic radicals have many special properties and can be applied to various fields,s uch as spintronics, [1] molecular magnets, [2] electron paramagnetic resonance (EPR) imaging, [3] organic field-effect transistors (OFETs), [4] organic rechargeable batteries, [5] and accelerating chemical reactions. [6] Recently,t he applications of organic radicals in organic light-emitting diodes (OLEDs) have attracted much attention. Duan et al employed an organic radical of o-MeO-DMBI as ad opant into Bphen or directly as an electron injection layer (EIL) to improve the electron injection and conductivity,thus obtained highly efficient and stable OLEDs.…”