The understanding of O-O bond formation is of great importance for revealing the mechanism of water oxidation in photosynthesis and for developing efficient catalysts for water oxidation in artificial photosynthesis. The chemical oxidation of the Ru(OH)(OH) core with the vicinal OH and OH ligands was spectroscopically and theoretically investigated to provide a mechanistic insight into the O-O bond formation in the core. We demonstrate O-O bond formation at the low-valent Ru(OH) core with the vicinal OH ligands to form the Ru(μ-OOH) core with a μ-OOH bridge. The O-O bond formation is induced by deprotonation of one of the OH ligands of Ru(OH) via intramolecular coupling of the OH and deprotonated O ligands, conjugated with two-electron transfer from two Ru centers to their ligands. The intersystem crossing between singlet and triple states of Ru(μ-OOH) is easily switched by exchange of H between the μ-OOH bridge and the auxiliary backbone ligand.
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http://dx.doi.org/10.1073/pnas.2113910118 | DOI Listing |
In biological systems, heme-copper oxidase (HCO) enzymes play a crucial role in the oxygen reduction reaction (ORR), where the pivotal O-O bond cleavage of the (heme)Fe-peroxo-Cu intermediate is facilitated by active-site (peroxo core) hydrogen bonding followed by proton-coupled electron transfer (PCET) from a nearby (phenolic) tyrosine residue. A useful approach to comprehend the fundamental relationships among H-bonding/proton/H-atom donors and their abilities to induce O-O bond homolysis involves the investigation of synthetic, bioinspired model systems where the exogenous substrate properties (such as p and bond dissociation energy (BDE)) can be systematically altered. This report details the reactivity of a heme-peroxo-copper HCO model complex (LS-4DCHIm) toward a series of substituted catechol substrates that span a range of p and O-H bond BDE values, exhibiting different reaction mechanisms.
View Article and Find Full Text PDFActa Crystallogr E Crystallogr Commun
January 2025
Département de Chimie Faculté des Sciences et Techniques Université Cheik Anta Diop Dakar Senegal.
In the binuclear title complex, [La(CHO)(CHN)(HO)](NO)·0.5HO, the two lanthanum ions are nine coordinate in a distorted trigonal-prismatic geometry. Each La ion is bonded to three N atoms of the Schiff base, 1-(pyridin-2-yl)-2-(pyridin-2-yl-methyl-ene)hydrazine and is coordinated by one acetate group, which acts in -bidentate mode and two acetate groups that act in -mode between the two La ions.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
China University of Petroleum East China, State Key Laboratory of Heavy Oil Processing, 66 The Yangtze River West Road, 266580, Qingdao, CHINA.
The production of hydrogen peroxide (H2O2) through two-electron oxygen reduction reaction (2e- ORR) has emerged as a more environmentally friendly alternative to the traditional anthraquinone method. Although oxidized carbon catalysts have intensive developed due to their high selectivity and activity, the yield and conversion rate of H2O2 under high overpotential still limited. The produced H2O2 was rapidly consumed by the increased intensity of H2O2 reduction, which could ascribe to decomposition of peroxide radicals under high voltage in the carbon catalyst.
View Article and Find Full Text PDFNat Commun
January 2025
State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials Oriented Chemical Engineering, School of Chemical Engineering, Dalian University of Technology, Dalian, China.
Regulating the spintronic structure of electrocatalysts can improve the oxygen evolution reaction performance efficiently. Nonetheless, the effects of tuning the spintronic structure for the oxygen evolution reaction mechanisms have rarely been discussed. Here, we show a ruthenium-cobalt-tin oxide with optimized spintronic structure due to the quantum spin interaction of Ru and Co.
View Article and Find Full Text PDFEnviron Technol
December 2024
School of Environmental Science and Engineering, Southwest Jiaotong University, Chengdu, People's Republic of China.
Ascorbic acid (AA) was used as a reducing agent to improve the Fe(III)-activated peracetic acid (PAA) system for the removal of sulfamethoxazole (SMX) in this work. The efficiency, influencing factors and mechanism of SMX elimination in the AA/Fe(III)/PAA process were studied. The results exhibited that AA facilitated the reduction of Fe(III) to Fe(II) and subsequently improved the activation of PAA and HO.
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