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  - Meza-Chincha, Ana-Lucia
A1  - Lindner, Joachim O.
A1  - Schindler, Dorothee
A1  - Schmidt, David
A1  - Krause, Ana-Maria
A1  - Röhr, Merle I. S.
A1  - Mitrić, Roland
A1  - Würthner, Frank
T1  - Impact of substituents on molecular properties and catalytic activities of trinuclear Ru macrocycles in water oxidation
N2  - Herein we report a broad series of new trinuclear supramolecular Ru(bda) macrocycles bearing different substituents at the axial or equatorial ligands which enabled investigation of substituent effects on the catalytic activities in chemical and photocatalytic water oxidation. Our detailed investigations revealed that the activities of these functionalized macrocycles in water oxidation are significantly affected by the position at which the substituents were introduced. Interestingly, this effect could not be explained based on the redox properties of the catalysts since these are not markedly influenced by the functionalization of the ligands. Instead, detailed investigations by X-ray crystal structure analysis and theoretical simulations showed that conformational changes imparted by the substituents are responsible for the variation of catalytic activities of the Ru macrocycles. For the first time, macrocyclic structure of this class of water oxidation catalysts is unequivocally confirmed and experimental indication for a hydrogen-bonded water network present in the cavity of the macrocycles is provided by crystal structure analysis. We ascribe the high catalytic efficiency of our Ru(bda) macrocycles to cooperative proton abstractions facilitated by such a network of preorganized water molecules in their cavity, which is reminiscent of catalytic activities of enzymes at active sites.
KW  - water oxidation
KW  - self-assembly
KW  - solar fuels
KW  - supramolecular materials
KW  - catalysis
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-204653
UR  - https://doi.org/10.1039/D0SC01097A
SN  - 2041-6539
ER  -