A Calix[4]arene‐Based Cyclic Dinuclear Ruthenium Complex for Light‐Driven Catalytic Water Oxidation. Issue 1 (26th November 2020)

• Record Type: Journal Article
• Authors: Noll, Niklas; Würthner, Frank
• Is Part Of: Chemistry. Volume 27:Issue 1(2021)
• Page Start: 444
• Page End: 450
• Publication Date: 2020-11-26
• Subjects: artificial photosynthesis -- homogenous catalysis -- photocatalysis -- ruthenium complexes -- water oxidation; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202004486
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: A cyclic dinuclear ruthenium(bda) (bda: 2, 2'‐bipyridine‐6, 6'‐dicarboxylate) complex equipped with oligo(ethylene glycol)‐functionalized axial calix[4]arene ligands has been synthesized for homogenous catalytic water oxidation. This novel Ru(bda) macrocycle showed significantly increased catalytic activity in chemical and photocatalytic water oxidation compared to the archetype mononuclear reference [Ru(bda)(pic)2 ]. Kinetic investigations, including kinetic isotope effect studies, disclosed a unimolecular water nucleophilic attack mechanism of this novel dinuclear water oxidation catalyst (WOC) under the involvement of the second coordination sphere. Photocatalytic water oxidation with this cyclic dinuclear Ru complex using [Ru(bpy)3 ]Cl2 as a standard photosensitizer revealed a turnover frequency of 15.5 s −1 and a turnover number of 460. This so far highest photocatalytic performance reported for a Ru(bda) complex underlines the potential of this water‐soluble WOC for artificial photosynthesis. Abstract : Making water run up a thermodynamic hill : The thermodynamically demanding oxidation of water to molecular oxygen is a critical bottleneck for the generation of carbon‐neutral fuels. Homogenous light‐driven water oxidation by a newly designed cyclic dinuclear Ru(bda) catalyst equipped with axial calix[4]arene ligands revealed an outstanding catalytic activity and is thus of potential interest for artificial photosynthesis.