Visible‐Light‐Driven Oxidation of Organic Substrates with Dioxygen Mediated by a [Ru(bpy)₃]²⁺/Laccase System

Abstract

Oxidation reactions are highly important chemical transformations that still require harsh reaction conditions and stoichiometric amounts of chemical oxidants that are often toxic. To circumvent these issues, olefins oxidation is achieved in mild conditions upon irradiation of an aqueous solution of the complex [Ru(bpy)3 ](2+) and the enzyme laccase. Epoxide formation is coupled to the light-driven reduction of O2 by [Ru(bpy)3 ](2+) /laccase system. The reactivity can be explained by dioxygen acting both as an oxidative agent and as renewable electron acceptor, avoiding the use of a sacrificial electron acceptor.

Efficiency of Site‐Specific Clicked Laccase–Carbon Nanotubes Biocathodes towards O2 Reduction

“…The original LAC3 sequence contains naturally only two lysine residues (K 40 and K 71 ) located at the surface of the amino‐terminus domain (GENEBANK AAR00925.1). These two residues bearing primary amine groups are easily functionalizable with chemical modules . We have recently described a general strategy for obtaining single surface located lysine variants of LAC3 (designed UNIK) .…”

“…Following our previous work on the orientation of pyrene‐laccase molecules at the MWCNT electrode surface, we initially compared in silico the pyrene‐UNIK 161 and (pyrene) 2 ‐LAC3 hybrid/MWCNT electrodes (Figure SI1, see Supporting Information for computational details). Modeling of the pyrene grafted K 40, K 71 and K 161 positions was performed as previously published . Distances from the anchor (pyrene) to the Cu II ions and electron conduction pathways in the protein matrix were evaluated for each hybrid model (see Table ).…”

“…A commercial 4‐ethynylbenzaldehyde was used for the “alkynylation” (i.e., functionalization with an alkyne group) of laccases in a reductive akylation reaction adapted from McFarland and Francis (see Supplementary Information). As previously evaluated, this functionalization strategy results in an approximately 1:1 ratio between the enzyme and the functional group . This unique anchor point in the UNIK‐alkyne variant is designed to allow for only one possible orientation of the laccase molecules after reaction (cycloaddition) at the azido‐modified surface of nanostructured electrodes.…”

Probing the Surface of a Laccase for Clues towards the Design of Chemo‐Enzymatic Catalysts

“…Expanding laccase reactivity through their combination with small and diffusible synthetic redox mediators is well documented . Recently, we have investigated bimolecular systems by associating the enzyme with palladium complexes (for alcohol oxidation) or ruthenium–polypyridyl photosensitisers (for epoxidation) taking advantage of the driving force of dioxygen reduction (1.23 V at pH 0) . However, bimolecular systems are intrinsically limited by diffusion.…”

Photobiokatalyse: Aktivierung von Redoxenzymen durch direkten oder indirekten Transfer photoinduzierter Elektronen

“…(1)]: [24,[110][111][112] In der Gegenwart von EDTAu nd [Ru(bpy) 3 ] 2+ war vollständig reduzierte Laccase in der Lage, O 2 mit einer TOFv on 18 h À1 zu reduzieren. [111] Mit p-Styrolsulfonat als Substrat wurde fürd ie Reduktion von O 2 eine TOFv on 30 h À1 erreicht. [24] Dass mit diesem ZnTMPyP 4+ /Laccase-System eine TOFv on 120 h À1 erreicht wurde,z eigt, dass die photoenzymatische Effizienz hauptsächlich durch die Art des verwendeten Photosensibilisators bestimmt wird.…”