Synthesis, Characterization, and Oxygenation Studies of Carboxylate‐Bridged Diiron(II) Complexes with Aromatic Substrates Tethered to Pyridine Ligands and the Formation of a Unique Trinuclear Complex

Friedle, Simone; Lippard, Stephen J.

doi:10.1002/ejic.200900821

Cited by 7 publications

(4 citation statements)

References 51 publications

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“…This conclusion was supported by EPR analysis of the oxygenated complexes, which showed the signal for a mononuclear Cu(II) center and the remaining two Cu(II) centers linked by hydroxo groups. − Magnetic studies revealed a ferromagnetically coupled Cu(II)Cu(II) center along with an isolated Cu(II) in these complexes . Although these tricopper complexes do not typically support hydrocarbon oxidation, they represent a popular approach to the problem, and ligand-assisted formation of trinuclear complexes has been reported for other metal ions such as manganese, iron, cobalt, and zinc, as well. − …”

Section: Toward the Development Of A Biomimetic Catalystmentioning

confidence: 86%

Alkane Oxidation: Methane Monooxygenases, Related Enzymes, and Their Biomimetics

et al. 2017

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Methane monooxygenases (MMOs) mediate the facile conversion of methane into methanol in methanotrophic bacteria with high efficiency under ambient conditions. Because the selective oxidation of methane is extremely challenging, there is considerable interest in understanding how these enzymes carry out this difficult chemistry. The impetus of these efforts is to learn from the microbes to develop a biomimetic catalyst to accomplish the same chemical transformation. Here, we review the progress made over the past two to three decades toward delineating the structures and functions of the catalytic sites in two MMOs: soluble methane monooxygenase (sMMO) and particulate methane monooxygenase (pMMO). sMMO is a water-soluble three-component protein complex consisting of a hydroxylase with a nonheme diiron catalytic site; pMMO is a membrane-bound metalloenzyme with a unique tricopper cluster as the site of hydroxylation. The metal cluster in each of these MMOs harnesses O to functionalize the C-H bond using different chemistry. We highlight some of the common basic principles that they share. Finally, the development of functional models of the catalytic sites of MMOs is described. These efforts have culminated in the first successful biomimetic catalyst capable of efficient methane oxidation without overoxidation at room temperature.

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Section: Toward the Development Of A Biomimetic Catalystmentioning

confidence: 86%

Alkane Oxidation: Methane Monooxygenases, Related Enzymes, and Their Biomimetics

et al. 2017

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“…Each of the three compounds shares some structural features, particularly the Ph–O–(Zn 2 )–OOC–Ph SBU from Scheme . While this SBU is commonly seen in dimeric − and polynuclear species, − very few MOFs were found in the CSD (version 5.35, Nov. 2013 and updates) with this motif. {[Zn 2 (H 2 dht)(dht) 0.5 (azpy) 0.5 (H 2 O)]·4 H 2 O} (H 2 dht = dihydroxyterphthalate, azpy = 4,4′-azobipyridine) is a particular example of a fluorescent MOF with this SBU .…”

Section: Resultsmentioning

confidence: 99%

Additive Effects in the Formation of Fluorescent Zinc Metal–Organic Frameworks with 5-Hydroxyisophthalate

Hill

El-Hankari

Chiacchia

et al. 2015

Crystal Growth & Design

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Three new metal-organic frameworks (MOFs) are formed from the reaction of zinc with 5-hydroxyisophthalic acid (H 3 -5-hip) with a range of additives in dimethylformamide (DMF). The additives include water, pyridine, and [Me n NH 4−n ]Cl (n = 0−4) and, through hydrogen bonding, have a marked effect on the formation and phase of any resultant MOF, often in a narrow range of sub-stoichiometric concentrations. The three MOFs, [Me 2 NH 2 ][Zn 2 (5-hip)(H-5-hip)(H 2 O)].3.25DMF (1), α-[Me 2 NH 2 ] 2 [Zn 2 (5-hip) 2 ]·2DMF (2) and [Me 2 NH 2 ][Me 4 N] 2 [Zn 4 (5-hip) 2 (H-5-hip 2.5 )]·3DMF (3) have solvent-accessible pores and the flexibility of the MOFs allows relaxation from a porous state to minimise the void space on desolvation. Topological analysis of the frameworks reveals two previously unrecorded MOF topologies. Compounds 2 and 3 are fluorescent while this property is absent in compound 1. We also present a revised structure for the closely-related β-[Me 2 NH 2 ] 2 [Zn 2 (5-hip) 2 ]·2DMF (4).

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“…This fortuitous discovery that high-valent diiron terphenylcarboxylate complexes could be intercepted by tethered substrates inspired subsequent studies of the reactivity of oxygenated intermediates toward organic moieties held in close proximity to the diiron center. Attachment of benzyl [84, 85], ethyl [85], ethynyl [86], phenoxyl [87], phosphido [84, 88], or sulfido [88, 89] units to an amine or pyridine ligand afforded a series of tethered substrates that could be easily incorporated into 13 , affording the corresponding diiron(II) compounds. After exposing the substrate/diiron(II) complex to O 2 , the reaction products were analyzed by gas chromatography-mass spectrometry (GC-MS).…”

Section: Ligand Platformsmentioning

confidence: 99%

Evolution of strategies to prepare synthetic mimics of carboxylate-bridged diiron protein active sites

Lippard

2011

Journal of Inorganic Biochemistry

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We present a comprehensive review of research conducted in our laboratory in pursuit of the long-term goal of reproducing the structures and reactivity of carboxylate-bridged diiron centers used in biology to activate dioxygen for the conversion of hydrocarbons to alcohols and related products. This article describes the evolution of strategies devised to achieve these goals and illustrates the challenges in getting there. Particular emphasis is placed on controlling the geometry and coordination environment of the diiron core, preventing formation of polynuclear iron clusters, maintaining the structural integrity of model complexes during reactions with dioxygen, and tuning the ligand framework to stabilize desired oxygenated diiron species. Studies of the various model systems have improved our understanding of the electronic and physical characteristics of carboxylate-bridged diiron units and their reactivity toward molecular oxygen and organic moieties. The principles and lessons that have emerged from these investigations will guide future efforts to develop more sophisticated diiron protein model complexes.

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Synthesis, Characterization, and Oxygenation Studies of Carboxylate‐Bridged Diiron(II) Complexes with Aromatic Substrates Tethered to Pyridine Ligands and the Formation of a Unique Trinuclear Complex

Cited by 7 publications

References 51 publications

Alkane Oxidation: Methane Monooxygenases, Related Enzymes, and Their Biomimetics

Alkane Oxidation: Methane Monooxygenases, Related Enzymes, and Their Biomimetics

Additive Effects in the Formation of Fluorescent Zinc Metal–Organic Frameworks with 5-Hydroxyisophthalate

Evolution of strategies to prepare synthetic mimics of carboxylate-bridged diiron protein active sites

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