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Noll N, Würthner F. Bioinspired Water Preorganization in Confined Space for Efficient Water Oxidation Catalysis in Metallosupramolecular Ruthenium Architectures. Acc Chem Res 2024; 57:1538-1549. [PMID: 38710509 PMCID: PMC11112732 DOI: 10.1021/acs.accounts.4c00148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 04/13/2024] [Accepted: 04/16/2024] [Indexed: 05/08/2024]
Abstract
ConspectusNature has established a sustainable way to maintain aerobic life on earth by inventing one of the most sophisticated biological processes, namely, natural photosynthesis, which delivers us with organic matter and molecular oxygen derived from the two abundant resources sunlight and water. The thermodynamically demanding photosynthetic water splitting is catalyzed by the oxygen-evolving complex in photosystem II (OEC-PSII), which comprises a distorted tetramanganese-calcium cluster (CaMn4O5) as catalytic core. As an ubiquitous concept for fine-tuning and regulating the reactivity of the active site of metalloenzymes, the surrounding protein domain creates a sophisticated environment that promotes substrate preorganization through secondary, noncovalent interactions such as hydrogen bonding or electrostatic interactions. Based on the high-resolution X-ray structure of PSII, several water channels were identified near the active site, which are filled with extensive hydrogen-bonding networks of preorganized water molecules, connecting the OEC with the protein surface. As an integral part of the outer coordination sphere of natural metalloenzymes, these channels control the substrate and product delivery, carefully regulate the proton flow by promoting pivotal proton-coupled electron transfer processes, and simultaneously stabilize short-lived oxidized intermediates, thus highlighting the importance of an ordered water network for the remarkable efficiency of the natural OEC.Transferring this concept from nature to the engineering of artificial metal catalysts for fuel production has fostered the fascinating field of metallosupramolecular chemistry by generating defined cavities that conceptually mimic enzymatic pockets. However, the application of supramolecular approaches to generate artificial water oxidation catalysts remained scarce prior to our initial reports, since such molecular design strategies for efficient activation of substrate water molecules in confined nanoenvironments were lacking. In this Account, we describe our research efforts on combining the state-of-the art Ru(bda) catalytic framework with structurally programmed ditopic ligands to guide the water oxidation process in defined metallosupramolecular assemblies in spatial proximity. We will elucidate the governing factors that control the quality of hydrogen-bonding water networks in multinuclear cavities of varying sizes and geometries to obtain high-performance, state-of-the-art water oxidation catalysts. Pushing the boundaries of artificial catalyst design, embedding a single catalytic Ru center into a well-defined molecular pocket enabled sophisticated water preorganization in front of the active site through an encoded basic recognition site, resulting in high catalytic rates comparable to those of the natural counterpart OEC-PSII.To fully explore their potential for solar fuel devices, the suitability of our metallosupramolecular assemblies was demonstrated under (electro)chemical and photocatalytic water oxidation conditions. In addition, testing the limits of structural diversity allowed the fabrication of self-assembled linear coordination oligomers as novel photocatalytic materials and long-range ordered covalent organic framework (COF) materials as recyclable and long-term stable solid-state materials for future applications.
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Affiliation(s)
- Niklas Noll
- Institut für Organische Chemie
& Center for Nanosystems Chemistry, Universität Würzburg, Am Hubland, 97074 Würzburg Germany
| | - Frank Würthner
- Institut für Organische Chemie
& Center for Nanosystems Chemistry, Universität Würzburg, Am Hubland, 97074 Würzburg Germany
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Singh A, Singh B, Dey S, Indra A, Lahiri GK. Ruthenium Azobis(benzothiazole): Electronic Structure and Impact of Substituents on the Electrocatalytic Single-Site Water Oxidation Process. Inorg Chem 2023; 62:2769-2783. [PMID: 36719385 DOI: 10.1021/acs.inorgchem.2c03906] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The present article deals with the structurally and spectroelectrochemically characterized newer class of ruthenium-azoheteroarenes [RuII(Ph-trpy)(Cl)(L)]ClO4, [1]ClO4-[3]ClO4 (Ph-trpy: 4'-phenyl-2,2':6',2″-terpyridine; L1: 2,2'-azobis(benzothiazole) ([1]ClO4); L2: 2,2'-azobis(6-methylbenzothiazole) ([2]ClO4); L3: 2,2'-azobis(6-chlorobenzothiazole) ([3]ClO4)). A collective consideration of experimental (i.e., structural and spectroelectrochemical) and theoretical (DFT calculations) results of [1]ClO4-[3]ClO4 established selective stabilization of (i) the unperturbed azo (N═N)0 function of L, (ii) the exclusive presence of the isomeric form involving the N(azo) donor of L trans to Cl, and (iii) the presence of extended, hydrogen-bonded trimeric units in the asymmetric unit of [2]ClO4 (CH---O) via the involvement of ClO4- anions. The detailed electrochemical studies revealed metal-based oxidation of [RuII(Ph-trpy)(Cl)(L)]+ (1+-3+) to [RuIII(Ph-trpy)(Cl)(L)]2+ (12+-32+); however, the electronic form of the first reduced state (1-3) could be better represented by its mixed RuII(Ph-trpy)(Cl)(L•-)/RuIII(Ph-trpy)(Cl)(L2-) state. Both native (1+-3+) and reduced (1-3) states exhibited weak lower energy transitions within the range of 1000-1200 nm. Further, [1]ClO4-[3]ClO4 delivered an electrochemical OER (oxygen evolution reaction) process in alkaline medium on immobilizing them to a carbon cloth support, which divulged an amplified water oxidation feature for [2]ClO4 due to the presence of electron-donating methyl groups in the L2 backbone. The faster OER kinetics and high catalytic stability of [2]ClO4 could also be rationalized by its lowest Tafel slope (85 mV dec-1) and choronoamperometric experiment (stable up to 12 h), respectively, along with high Faradic efficiency (∼97%). A comparison of [2]ClO4 with the reported analogous ruthenium complexes furnished its excellent intrinsic water oxidation activity.
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Affiliation(s)
- Aditi Singh
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Baghendra Singh
- Department of Chemistry, Indian Institute of Technology (BHU), Varanasi, Uttar Pradesh 221005, India
| | - Sanchaita Dey
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Arindam Indra
- Department of Chemistry, Indian Institute of Technology (BHU), Varanasi, Uttar Pradesh 221005, India
| | - Goutam Kumar Lahiri
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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Noll N, Groß T, Shoyama K, Beuerle F, Würthner F. Folding-Induced Promotion of Proton-Coupled Electron Transfers via Proximal Base for Light-Driven Water Oxidation. Angew Chem Int Ed Engl 2023; 62:e202217745. [PMID: 36511298 PMCID: PMC10107485 DOI: 10.1002/anie.202217745] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 12/14/2022]
Abstract
Proton-coupled electron-transfer (PCET) processes play a key role in biocatalytic energy conversion and storage, for example, photosynthesis or nitrogen fixation. Here, we report a series of bipyridine-containing di- to tetranuclear Ru(bda) macrocycles 2 C-4 C (bda: 2,2'-bipyridine-6,6'-dicarboxylate) to promote O-O bond formation. In photocatalytic water oxidation under neutral conditions, all complexes 2 C-4 C prevail in a folded conformation that support the water nucleophilic attack (WNA) pathway with remarkable turnover frequencies of up to 15.5 s-1 per Ru unit respectively. Single-crystal X-ray analysis revealed an increased tendency for intramolecular π-π stacking and preorganization of the proximal bases close to the active centers for the larger macrocycles. H/D kinetic isotope effect studies and electrochemical data demonstrate the key role of the proximal bipyridines as proton acceptors in lowering the activation barrier for the crucial nucleophilic attack of H2 O in the WNA mechanism.
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Affiliation(s)
- Niklas Noll
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Tobias Groß
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Kazutaka Shoyama
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.,Center for Nanosystems Chemistry (CNC), Universität Würzburg, Theodor-Boveri-Weg, 97074, Würzburg, Germany
| | - Florian Beuerle
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.,Center for Nanosystems Chemistry (CNC), Universität Würzburg, Theodor-Boveri-Weg, 97074, Würzburg, Germany.,Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, 72076, Tübingen, Germany
| | - Frank Würthner
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.,Center for Nanosystems Chemistry (CNC), Universität Würzburg, Theodor-Boveri-Weg, 97074, Würzburg, Germany
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Ham R, Nielsen CJ, Pullen S, Reek JNH. Supramolecular Coordination Cages for Artificial Photosynthesis and Synthetic Photocatalysis. Chem Rev 2023; 123:5225-5261. [PMID: 36662702 PMCID: PMC10176487 DOI: 10.1021/acs.chemrev.2c00759] [Citation(s) in RCA: 47] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Because sunlight is the most abundant energy source on earth, it has huge potential for practical applications ranging from sustainable energy supply to light driven chemistry. From a chemical perspective, excited states generated by light make thermodynamically uphill reactions possible, which forms the basis for energy storage into fuels. In addition, with light, open-shell species can be generated which open up new reaction pathways in organic synthesis. Crucial are photosensitizers, which absorb light and transfer energy to substrates by various mechanisms, processes that highly depend on the distance between the molecules involved. Supramolecular coordination cages are well studied and synthetically accessible reaction vessels with single cavities for guest binding, ensuring close proximity of different components. Due to high modularity of their size, shape, and the nature of metal centers and ligands, cages are ideal platforms to exploit preorganization in photocatalysis. Herein we focus on the application of supramolecular cages for photocatalysis in artificial photosynthesis and in organic photo(redox) catalysis. Finally, a brief overview of immobilization strategies for supramolecular cages provides tools for implementing cages into devices. This review provides inspiration for future design of photocatalytic supramolecular host-guest systems and their application in producing solar fuels and complex organic molecules.
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Affiliation(s)
- Rens Ham
- Homogeneous and Supramolecular Catalysis, Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, 1098 XHAmsterdam, The Netherlands
| | - C Jasslie Nielsen
- Homogeneous and Supramolecular Catalysis, Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, 1098 XHAmsterdam, The Netherlands
| | - Sonja Pullen
- Homogeneous and Supramolecular Catalysis, Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, 1098 XHAmsterdam, The Netherlands
| | - Joost N H Reek
- Homogeneous and Supramolecular Catalysis, Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, 1098 XHAmsterdam, The Netherlands
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Das R, Linseis M, Scheerer S, Zoller K, Senft L, Ivanović-Burmazović I, Winter RF. Reversible Multielectron Release from Redox-Active Three-Dimensional Molecular Barrels with Ruthenium-Alkenyl Moieties. Inorg Chem 2022; 61:12662-12677. [PMID: 35917328 DOI: 10.1021/acs.inorgchem.2c01608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Three-dimensional molecular barrels Ru6-4 and Ru6-5 were synthesized in high yields from dinuclear ruthenium-vinyl clamps and tritopic triphenylamine-derived carboxylate linkers and characterized by multinuclear NMR spectroscopy including 1H-1H COSY and 1H DOSY measurements, high-resolution electrospray ionization mass spectrometry, and X-ray crystallography. The metal frameworks of the cages adopt the shape of twisted trigonal prisms, and they crystallize as racemic mixtures of interdigitating Δ- and Λ-enantiomers with a tight columnar packing in Ru6-4. Electrochemical studies and redox titrations revealed that the cages are able to release up to 11 electrons on the voltammetric timescale and that their cage structures persist up to the hexacation level. IR and UV-vis-near-infrared spectroelectrochemical studies confirm substituent-dependent intramolecular electronic communication within the π-conjugated 1,3-divinylphenylene backbone in the tricationic states, where all three divinylphenylene-bridged diruthenium clamps are present in mixed-valent radical cation states. The formation of 1:3 charge-transfer salts with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane as the electron acceptor is also demonstrated.
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Affiliation(s)
- Rajorshi Das
- Fachbereich Chemie, Universität Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Michael Linseis
- Fachbereich Chemie, Universität Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Stefan Scheerer
- Fachbereich Chemie, Universität Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Katrin Zoller
- Fachbereich Chemie, Universität Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Laura Senft
- Department Chemie, Ludwig-Maximilians Universität München, Butenandtstraße 5-13, Haus D, 81377 München, Germany
| | - Ivana Ivanović-Burmazović
- Department Chemie, Ludwig-Maximilians Universität München, Butenandtstraße 5-13, Haus D, 81377 München, Germany
| | - Rainer F Winter
- Fachbereich Chemie, Universität Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
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Amthor S, Keil P, Nauroozi D, Perleth D, Rau S. A Phosphonate Substituent in a 1,10‐Phenanthroline Ligand Boosts Light‐Driven Catalytic Water Oxidation Performance Sensitized by Ruthenium Chromophores. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202100656] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Sebastian Amthor
- Institute of Inorganic Chemistry I Ulm University Albert-Einstein-Allee 11 89081 Ulm Germany
| | - Philip Keil
- Institute of Inorganic Chemistry I Ulm University Albert-Einstein-Allee 11 89081 Ulm Germany
| | - Djawed Nauroozi
- Institute of Inorganic Chemistry I Ulm University Albert-Einstein-Allee 11 89081 Ulm Germany
| | - Daniel Perleth
- Institute of Inorganic Chemistry I Ulm University Albert-Einstein-Allee 11 89081 Ulm Germany
| | - Sven Rau
- Institute of Inorganic Chemistry I Ulm University Albert-Einstein-Allee 11 89081 Ulm Germany
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Schindler D, Meza-Chincha AL, Roth M, Würthner F. Structure-Activity Relationship for Di- up to Tetranuclear Macrocyclic Ruthenium Catalysts in Homogeneous Water Oxidation. Chemistry 2021; 27:16938-16946. [PMID: 33909302 PMCID: PMC9290496 DOI: 10.1002/chem.202100549] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Indexed: 12/13/2022]
Abstract
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 s-1 to 8.7 s-1 and 10.5 s-1 in chemical and 0.6 s-1 to 3.3 s-1 and 5.8 s-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.
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Affiliation(s)
- Dorothee Schindler
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Ana-Lucia Meza-Chincha
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Maximilian Roth
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Frank Würthner
- Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.,Center for Nanosystems Chemistry (CNC), Universität Würzburg, Theodor-Boveri-Weg, 97074, Würzburg, Germany
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Lin HY, Zhou LY, Xu L. Photocatalysis in Supramolecular Fluorescent Metallacycles and Metallacages. Chem Asian J 2021; 16:3805-3816. [PMID: 34529337 DOI: 10.1002/asia.202100942] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/13/2021] [Indexed: 11/08/2022]
Abstract
The utilization of photocatalytic techniques for achieving light-to-fuel conversion is a promising way to ease the shortage of energy and degradation of the ecological environment. Fluorescent metallacycles and metallacages have drawn considerable attention and have been used in widespread fields due to easy preparation and their abundant functionality including photocatalysis. This review covers recent advances in photocatalysis in discrete supramolecular fluorescent metallacycles and metallacages. The developments in the utilization of the metallacycles skeletons and the effect of fluorescence-resonance energy transfer for photocatalysis are discussed. Furthermore, the use of the ligands decorated by organic chromophores or redox metal sites in metallacages as photocatalysts and their ability to encapsulate appropriate catalytic cofactors for photocatalysis are summarized. For the sake of brevity, macrocycles and cages with inorganic coordination complexes such as ruthenium complexes and iridium complexes are not included in this minireview.
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Affiliation(s)
- Hong-Yu Lin
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, 3663 N. Zhongshan Road, Shanghai, 200062, P. R. China
| | - Le-Yong Zhou
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, 3663 N. Zhongshan Road, Shanghai, 200062, P. R. China
| | - Lin Xu
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, 3663 N. Zhongshan Road, Shanghai, 200062, P. R. China
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