TY  - JOUR
A1  - Schindler, Dorothee
A1  - Meza-Chincha, Anna-Lucia
A1  - Roth, Maximilian
A1  - Würthner, Frank
T1  - Structure-Activity Relationship for Di- up to Tetranuclear Macrocyclic Ruthenium Catalysts in Homogeneous Water Oxidation
JF  - Chemistry—A European Journal
N2  - Two di- and tetranuclear Ru(bda) (bda: 2,2′-bipyridine-6,6′-dicarboxylate) macrocyclic complexes were synthesized and their catalytic activities in chemical and photochemical water oxidation investigated in a comparative manner to our previously reported trinuclear congener. Our studies have shown that the catalytic activities of this homologous series of multinuclear Ru(bda) macrocycles in homogeneous water oxidation are dependent on their size, exhibiting highest efficiencies for the largest tetranuclear catalyst. The turnover frequencies (TOFs) have increased from di- to tetranuclear macrocycles not only per catalyst molecule but more importantly also per Ru unit with TOF of 6 \(^{-1}\) to 8.7 \(^{-1}\) and 10.5 s\(^{-1}\) in chemical and 0.6 s\(^{-1}\) to 3.3 \(^{-1}\) and 5.8 \(^{-1}\) in photochemical water oxidation per Ru unit, respectively. Thus, for the first time, a clear structure–activity relationship could be established for this novel class of macrocyclic water oxidation catalysts.
KW  - homogeneous catalysis
KW  - water oxidation
KW  - ruthenium catalysts
KW  - renewable fuels
KW  - metallomacrocycles
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256792
VL  - 27
IS  - 68
ER  - 
TY  - JOUR
A1  - Würthner, Frank
A1  - Meza-Chincha, Ana-Lucia
A1  - Schindler, Dorothee
A1  - Natali, Mirco
T1  - Effects of Photosensitizers and Reaction Media on Light‐Driven Water Oxidation with Trinuclear Ruthenium Macrocycles
JF  - ChemPhotoChem
N2  - Photocatalytic water oxidation is a promising process for the production of solar fuels and the elucidation of factors that influence this process is of high significance. Thus, we have studied in detail light‐driven water oxidation with a trinuclear Ru(bda) (bda: 2,2’‐bipyridine‐6,6’‐dicarboxylate) macrocycle MC3 and its highly water soluble derivative m‐CH\(_2\)NMe\(_2\)‐MC3 using a series of ruthenium tris(bipyridine) complexes as photosensitizers under varied reaction conditions. Our investigations showed that the catalytic activities of these Ru macrocycles are significantly affected by the choice of photosensitizer (PS) and reaction media, in addition to buffer concentration, light intensity and concentration of the sensitizer. Our steady‐state and transient spectroscopic studies revealed that the photocatalytic performance of trinuclear Ru(bda) macrocycles is not limited by their intrinsic catalytic activities but rather by the efficiency of photogeneration of oxidant PS\(^+\) and its ability to act as an oxidizing agent to the catalysts as both are strongly dependent on the choice of photosensitizer and the amount of employed organic co‐solvent.
KW  - photosenitizers
KW  - water oxidation
KW  - ruthenium complexes
KW  - macrocycles
KW  - trinuclear
KW  - homogenous catalysis
KW  - photocatalysis
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-230116
VL  - 5
IS  - 2
ER  - 
TY  - JOUR
A1  - Würthner, Frank
A1  - Noll, Niklas
T1  - A Calix[4]arene‐Based Cyclic Dinuclear Ruthenium Complex for Light‐Driven Catalytic Water Oxidation
JF  - Chemistry - A European Journal
N2  - 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)\(_3\)]Cl\(_2\) 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.
KW  - water
KW  - oxidation
KW  - ruthenium
KW  - dinuclear
KW  - catalytic
KW  - artificial photosynthesis
KW  - homogenous catalysis
KW  - photocatalysis
KW  - ruthenium complexes
KW  - water oxidation
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-230030
UR  - https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202004486
VL  - 27
IS  - 1
ER  -