Electron-Donating para-Substituent (X) Enhances the Water Oxidation Activity of the Catalyst Ru(4′-X-terpyridine)(phenanthroline-SO3)+
Year: 2025
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Recently, our group has developed a Ru-based water oxidation catalyst (WOC) with pendant sulfonate ( 1, Ru(4′-X-terpyridine)(phenanthroline-SO 3 )OTf (X = H, 1a ) that shows high activity under both sacrificial oxidant (CAN, Ce(NH 4 ) 2 (NO 3 ) 6, Ce IV ) and electrocatalytic conditions, in both acidic and neutral media. Here, we demonstrate that the functionalization of the 4′-X-terpyridine ligand with an electron-donating substituent X = OEt (1b) makes potentials of Ru II /Ru III redox catalysis more negative, whereas when X = NO 2 (1c) and CF 3 (1d), potentials are more positive. For 1b, full conversion of the sacrificial oxidant Ce IV occurred in 0.4 h (7 h for 1a ), with an initial rate of 2.07 μmol O 2 s –1 and a turnover frequency of 7.6 s –1, which is 30-fold faster than that for 1a at [cat] 0 = 20 μM. Under electrocatalytic conditions, water oxidation by 1b is three times faster than that by the parent catalyst 1a at close to the same potential. Extensive computations have identified differences in the initial PCET steps of the water oxidation by catalysts 1a, 1b, and 1d, and demonstrated the increased probability of the O 2 formation via the oxide relay pathway in the order 1b < 1a < 1d .
Source: Inorganic Chemistry
Authors: Miguel A. Ibañez, Colton J. Breyer, Milan Gembicky, Zinnun F. Malikov, Djamaladdin G. Musaev, Douglas B. Grotjahn
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
OpenAlex ID: W4407240803