The Ru−Hbpp Water Oxidation Catalyst

Bozoglián, Fernando; Romain, Sophie; Ertem, Mehmed Z.; Todorova, Tanya K.; Sens, Christina; Mola, Joaquim; Rodrı́guez, Montserrat; Romero, Isabel; Benet‐Buchholz, Jordi; Fontrodona, Xavier; Cramer, Christopher J.; Gagliardi, Laura; Llobet, Antoni

doi:10.1021/ja9036127

Cited by 255 publications

(220 citation statements)

References 61 publications

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“…[150] However,B ozoglian et al found that the barrier for water insertionf rom the peroxide intermediate was associatedw ith ab arriero f 27.1 kcal mol À1 , [73] which was much lower than that found by Yang andB aik. [150] The differencew as suggestedt oc ome from the different density functional used, B3LYP versus M06L.…”

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confidence: 88%

Quantum Chemical Modeling of Homogeneous Water Oxidation Catalysis

Liao

Siegbahn

2017

ChemSusChem

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The design of efficient and robust water oxidation catalysts has proven challenging in the development of artificial photosynthetic systems for solar energy harnessing and storage. Tremendous progress has been made in the development of homogeneous transition‐metal complexes capable of mediating water oxidation. To improve the efficiency of the catalyst and to design new catalysts, a detailed mechanistic understanding is necessary. Quantum chemical modeling calculations have been successfully used to complement the experimental techniques to suggest a catalytic mechanism and identify all stationary points, including transition states for both O−O bond formation and O2 release. In this review, recent progress in the applications of quantum chemical methods for the modeling of homogeneous water oxidation catalysis, covering various transition metals, including manganese, iron, cobalt, nickel, copper, ruthenium, and iridium, is discussed.

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confidence: 88%

Quantum Chemical Modeling of Homogeneous Water Oxidation Catalysis

Liao

Siegbahn

2017

ChemSusChem

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“…Formation. Accumulated experimental and theoretical studies (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29) on artificial photosynthesis systems have elucidated dual possible mechanisms of the water splitting reaction: (i) the radical coupling (RC) mechanism and (ii) the acid-base mechanism. Tanaka and coworkers have proposed the former mechanism for the water splitting reaction by their Ru-quinone complexes as illustrated in Fig.…”

Section: Possible Electronic and Spin States Of Mononuclear And Binucmentioning

confidence: 99%

“…In the past decades, a number of experimental and theoretical studies (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29) have been performed to design artificial photosynthetic systems that mimic native PSII systems. Many binuclear transition-metal catalysts such as LðH 2 OÞM-O-MðOH 2 ÞL or LðH 2 OÞM-BL-MðOH 2 Þ (where L and BL are nonbridging and bridging organic ligands, respectively) were prepared and characterized for their catalytic properties toward water oxidation (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21).…”

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confidence: 99%

Similarities of artificial photosystems by ruthenium oxo complexes and native water splitting systems

Tanaka

Isobe

Yamanaka

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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The nature of chemical bonds of ruthenium(Ru)-quinine(Q) complexes, mononuclear ½RuðtrpyÞð3,5-t-Bu 2 QÞðOH 2 Þ ðClO 4 Þ 2 (trpy ¼ 2,2 0 : 6 0 ,2 0 0 -terpyridine, 3,5-di-tert-butyl-1,2-benzoquinone) (1), and binuclear ½Ru 2 ðbtpyanÞð3,6-di-Bu 2 QÞ 2 ðOH 2 Þ 2þ ðbtpyan ¼ 1,8-bisð2,2 0 : 6 0 ,2 0 0 -terpyrid-4 0 -ylÞanthracene, 3,6-t-Bu 2 Q ¼ 3,6-di-tertbutyl-1,2-benzoquinone) (2), has been investigated by broken-symmetry (BS) hybrid density functional (DFT) methods. BS DFT computations for the Ru complexes have elucidated that the closed-shell structure (2b) Ru(II)-Q complex is less stable than the open-shell structure (2bb) consisting of Ru(III) and semiquinone (SQ) radical fragments. These computations have also elucidated eight different electronic and spin structures of tetraradical intermediates that may be generated in the course of water splitting reaction. The Heisenberg spin Hamiltonian model for these species has been derived to elucidate six different effective exchange interactions (J) for four spin systems. Six J values have been determined using total energies of the eight (or seven) BS solutions for different spin configurations. The natural orbital analyses of these BS DFTsolutions have also been performed in order to obtain natural orbitals and their occupation numbers, which are useful for the lucid understanding of the nature of chemical bonds of the Ru complexes. Implications of the computational results are discussed in relation to the proposed reaction mechanisms of water splitting reaction in artificial photosynthesis systems and the similarity between artificial and native water splitting systems.four redox center | manganese clusters | water oxidation | oxyl radical | O-O bond formation P hotosynthesis is one of the most important chemical processes on our planet. Extensive experimental studies (1-6) on the process have revealed that oxygenic photosynthesis involves several protein-cofactor complexes embedded in the photosynthetic thylakoid membranes of plants, green algae, and cyanobacteria. Among these complexes, photosystem II (PSII) has a prominent role because it catalyzes the oxidation of water (, which is the prerequisite for all aerobic life. The main cyclic process to catalyze the water-oxidation consists of successive four steps, which is referred to as the Kok cycle (6). During this process, the oxygen-evolving complex (OEC), the catalyst of the water oxidation reaction, takes five oxidation states (S 0 -S 4 ). The OEC in PSII contains an inorganic cluster consisting of four manganese ions and one calcium ion that are bridged by at least five oxygens; the active site is therefore expressed with the CaMn 4 O 5 cluster (3) (5). Very recently, the electronic structure and reactivity of 3 (7-10) have been elucidated based on the new high-resolution X-ray structure (5).In the past decades, a number of experimental and theoretical studies (11-29) have been performed to design artificial photosynthetic systems that mimic native PSII systems. Many binuclear transition-metal catalysts s...

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“…18,19,20,21,22 When combined with the theoretical analysis, via density functional theory (DFT) calculations, spectroscopic and electrochemical measurements provide detailed information on the nature of reaction intermediates and activation free energies along the catalytic cycle of water oxidation. 23,24,25,26,27,28,29,30 Strong sigma donation groups like carboxylate ligands in 2,2'-bipyridine-6,6'-dicarboxylic acid (H 2 bda; see Chart 1 for a drawing), together with seven coordination have allowed easy access to reactive species in high oxidation states such as [Ru V (O)(bda)(pic) 2 ] + (pic is 4-picoline) where the metal center is at formal oxidation state of V. 31 Additional tuning of the activation energy barriers can result from supramolecular interactions, based on π-π stacking of ligands with π -extended conjugation such as isoquinoline and its derivatives favoring formation of dinuclear peroxo intermediates. 32,33 Furthermore, hydrogen bonding interactions can play a significant role in the kinetics as demonstrated with strategically substituted fluro-2,2'-bpy ligands.…”

Section: Introductionmentioning

confidence: 99%