Tailoring dicobalt Pacman complexes of Schiff-base calixpyrroles towards dioxygenreduction catalysis

Askarizadeh, Elham; Yaghoob, Sahar Bani; Boghaei, Davar M.; Slawin, Alexandra M. Z.; Love, Jason B.

doi:10.1039/b923189g

Cited by 62 publications

(55 citation statements)

References 34 publications

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“…Catalytic O 2 reduction has been promoted by bimetallic platforms afforded by either cofacial Schiff-base calixpyrrole [14][15][16][17] or porphyrin Pacman systems. [18][19][20][21][22][23] Initially, the 4209 lated and characterized during the two-step synthesis procedure, including a hydroxylated version of the boronic acid substituted precursor molecule derived by a base-assisted rearrangement.…”

Section: Introductionmentioning

confidence: 99%

High‐Yielding Synthesis of a Hetero‐Pacman Compound and the Characterization of Intermediates and Side‐Products

et al. 2014

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Through an optimized synthetic procedure, metalloligand 5, which features a hetero-Pacman scaffold comprising a porphyrin and a terpyridine moiety, has been assembled by a double Suzuki reaction. In a subsequent step, a rutheniumbipyridine fragment was introduced at the terpyridine coordination site of metalloligand 5 to form complex 6, which was fully characterized and its potential application in water oxidation catalysis tested. A number of side-products were iso-[a] Institute Scheme 1. Synthesis of compound 6 (mes = mesityl). Reagents and conditions: a) i. BuLi, B(OMe) 3 ; ii. H + /H 2 O; b) 2, [Pd(dppf)Cl 2 ], Rb 2 CO 3 , thf; c) CHCl 3 /MeOH; d) 4, [Pd(dppf)Cl 2 ], Rb 2 CO 3 , dioxane/water; e) i. [Ru(CH 3 CN) 2 (bpy)Cl 2 ], acetone; ii. NH 4 PF 6 /H 2 O.

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Section: Introductionmentioning

confidence: 99%

High‐Yielding Synthesis of a Hetero‐Pacman Compound and the Characterization of Intermediates and Side‐Products

et al. 2014

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“…Solution variable temperature kinetic studies and detection of reactive metal–O 2 intermediates reveal the controlling factors in the two- vs four-electron reduction of O 2 with metal complexes. 29-35 The key feature is the modification of supporting ligand environments which can allow for differing copper-dioxygen intermediates.…”

Section: Introductionmentioning

confidence: 99%

Acid-Induced Mechanism Change and Overpotential Decrease in Dioxygen Reduction Catalysis with a Dinuclear Copper Complex

et al. 2013

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Catalytic four-electron reduction of O2 by ferrocene (Fc) and 1,1′-dimethylferrocene (Me2Fc) occurs efficiently with a dinuclear copper(II) complex [CuII2(XYLO)(OH)]2+ (1), where XYLO is a m-xylene-linked bis[(2-(2-pyridyl)ethyl)amine dinucleating ligand with copper-bridging phenolate moiety], in the presence of perchloric acid (HClO4) in acetone at 298 K. The hydroxide and phenoxo group in [CuII2(XYLO)(OH)]2+ (1) undergo protonation with HClO4 to produce [CuII2(XYLOH)]4+ (2) where the two copper centers become independent and the reduction potential shifts from −0.68 V vs SCE in the absence of HClO4 to 0.47 Vj this makes possible the use of relatively weak one-electron reductants such as Fc and Me2Fc, significantly reducing the effective overpotential in the catalytic O2-reduction reaction. The mechanism of the reaction has been clarified based on kinetic studies on the overall catalytic reaction as well as each step in the catalytic cycle and also by low-temperature detection of intermediates. The O2-binding to the fully reduced complex [CuI2(XYLOH)]2+ (3) results in the reversible formation of the hydroperoxo complex ([CuII2(XYLO)(OOH)]2+) (4), followed by proton-coupled electron-transfer (PCET) reduction to complete the overall O2-to-2H2O catalytic conversion.

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“…These bimetallic scaffolds are also competent in the activation and reduction of dioxygen. [50][51][52][53][54][55] To this end, metal-polypyridine complexes exhibit rich photo-and electrochemistry with regard to the activation of reactants, especially oxygen-based small molecules. Bis(terpyridine) Pacman compounds of diruthenium [56][57][58] and Pt À Ru [59] complexes have been prepared, but the preparation of a Pacman system that combines the attractive properties of a porphyrin active site and metal polypyridine in a single Pacman architecture has yet to be achieved.…”

Section: Introductionmentioning

confidence: 99%

Terpyridine–Porphyrin Hetero‐Pacman Compounds

Schwalbe

Metzinger

Teets

et al. 2012

Chemistry A European J

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The two different coordination spheres afforded by Pacman architectures offer cooperativity derived from two different metal centers. A modular strategy is developed to produce a hetero-Pacman scaffold featuring a porphyrin and terpyridine for metal-ion binding. A double Suzuki reaction was employed to first attach a terpyridine moiety to a xanthene backbone and then attach a porphyrin. The new hetero-Pacman scaffold has been characterized and all building blocks have been isolated and structurally characterized. The principle objective to incorporate different metal centers was confirmed by isolating a trinuclear complex comprising two porphyrinic units and a bis(terpyridine)-iron unit. The compounds described herein expand the Pacman scaffold concept by allowing for the incorporation of a terpyridine-metal complex proximate to a porphyrin-cofactor active site for small-molecule activation.

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Tailoring dicobalt Pacman complexes of Schiff-base calixpyrroles towards dioxygenreduction catalysis

Abstract: By modifying the mouth of a macrocyclic dicobalt Pacman complex, it is possible to both isolate new bridging-superoxo and hydroxyl complexes and to tune the reactivity of this system towards catalytic fourelectron reduction of dioxygen to water.

Cited by 62 publications

References 34 publications

High‐Yielding Synthesis of a Hetero‐Pacman Compound and the Characterization of Intermediates and Side‐Products

High‐Yielding Synthesis of a Hetero‐Pacman Compound and the Characterization of Intermediates and Side‐Products

Acid-Induced Mechanism Change and Overpotential Decrease in Dioxygen Reduction Catalysis with a Dinuclear Copper Complex

Terpyridine–Porphyrin Hetero‐Pacman Compounds

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