Biomimetic functional models of the mononuclear copper enzyme galactose oxidase are presented that catalytically oxidize benzylic and allylic alcohols to aldehydes with O 2 under mild conditions. The mechanistic fidelity between natural system is pronounced. Modest structural mimicry proves sufficient transfer an unusual ligand-based radical mechanism, previously unprecedented outside protein matrix, a simple chemical system.

The binuclear copper enzyme tyrosinase activates O2 to form a mu-eta2:eta2-peroxodicopper(II) complex, which oxidizes phenols catechols. Here, synthetic with an absorption spectrum similar that of the enzymatic active oxidant, is reported rapidly hydroxylate phenolates at -80 degrees C. Upon phenolate addition extreme temperature in solution (-120 C), reactive intermediate consistent bis-mu-oxodicopper(III)-phenolate O-O bond fully cleaved, observed experimentally. subsequent hydroxylation...

The reaction of metal complexes with dioxygen (O 2 ) generally proceeds in 1:1, 2:1, or 4:1 (metal:O stoichiometry. A discrete, structurally characterized 3:1 product is presented. This mixed-valence trinuclear copper cluster, which contains the highly oxidized trivalent oxidation state, exhibits O bond scission and intriguing structural, spectroscopic, redox properties. relevance this synthetic complex to reduction at active sites multicopper oxidases discussed.

The complex [MnII(R,R-mcp)(CF3SO3)2] is an efficient and practical catalyst for the epoxidation of electron-deficient olefins. This capable epoxidizing olefins with as little 0.1 mol % in under 5 min using 1.2 equiv peracetic acid terminal oxidant. A wide scope substrates are epoxidized including terminal, tertiary, cis trans internal, enones, methacrylates >85% isolated yields.

Lipoxygenases are mononuclear non-heme iron enzymes that regio- and stereospecifcally convert 1,4-pentadiene subunit-containing fatty acids into alkyl peroxides. The rate-determining step is generally accepted to be hydrogen atom abstraction from the pentadiene subunit of substrate by an active ferric hydroxide species give a ferrous water organic radical. Reported here synthesis characterization model complex, [FeIII(PY5)(OMe)](OTf)2, reacts with substrates in manner similar proposed...

Highly oxidized metals are constituents of oxidants, reactive intermediates, and materials with interesting conductive magnetic properties. High-energy spectroscopies have played an important role in identifying describing the bonding character highly these materials. A systematic study Cu(III) K-edge X-ray absorption spectra was carried out to identify analytically useful signatures K-edge, elucidate descriptions for Cu(III)-containing complexes. K-edges six complexes their same-ligand...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTIrreversible Reduction of Dioxygen by Simple Peralkylated Diamine−Copper(I) Complexes: Characterization and Thermal Stability a [Cu2(μ-O)2]2+ CoreViswanath Mahadevan, Zhiguo Hou, Adam P. Cole, David E. Root, Tapan K. Lal, Edward I. Solomon, T. D. StackView Author Information Department Chemistry, Stanford University Stanford, California 94305 Cite this: J. Am. Chem. Soc. 1997, 119, 49, 11996–11997Publication Date (Web):December 10,...

Class III delocalization? The isolation and analysis of the ligand-radical title complex has allowed description changes in bonding from reduced form as well extent delocalization. intense low-energy absorption oxidized can be described a transition highly delocalized class mixed-valence compound. Supporting information for this article is available on WWW under http://www.wiley-vch.de/contents/jc_2002/2007/z701194_s.pdf or author. Please note: publisher not responsible content functionality...

Lipoxygenases are mononuclear non-heme metalloenzymes that regio- and stereospecifically convert 1,4-pentadiene subunit-containing fatty acids into alkyl peroxides. The rate-determining step is generally accepted to be hydrogen atom abstraction from the pentadiene subunit of substrate by an active metal(III)-hydroxide species give a metal(II)-water organic radical. All known plant animal lipoxygenases contain iron as metal; recently, however, manganese was found metal in fungal lipoxygenase....

The geometric and electronic structure of an oxidized Cu complex ([CuSal]+; Sal = N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexane-(1R,2R)-diamine) with a non-innocent salen ligand has been investigated both in the solid state solution. Integration information from UV−vis−NIR spectroscopy, magnetic susceptibility, electrochemistry, resonance Raman X-ray crystallography, absorption density functional theory calculations provides critical insights into nature localization/delocalization...

A new hybrid permethylated-amine-guanidine ligand based on a 1,3-propanediamine backbone (2L) and its Cu−O2 chemistry is reported. [(2L)CuI(MeCN)]1+ complex readily oxygenates at low temperatures in polar aprotic solvents to form bis(μ-oxo)dicopper(III) (O) species (2b), similar the parent bis-guanidine (1b) permethylated-diamine (3b). UV−vis X-ray absorption spectroscopy experiments confirm this assignment of 2b as an O species, full formation 2:1 demonstrated by optical titration with...

A CuI complex of 3-ethynyl-phenanthroline covalently immobilized onto an azide-modified glassy carbon surface is active electrocatalyst for the four-electron (4-e) reduction O2 to H2O. The rate second-order in Cu coverage at moderate overpotential, suggesting that two species are necessary efficient 4-e O2. Mechanisms proposed consistent with observations this system and previously reported results a similar physisorbed system.

The present study provides mechanistic details of a mild aromatic C−H activation effected by copper(II) center ligated in triazamacrocylic ligand, affording equimolar amounts CuIII-aryl species and CuI as reaction products. At low temperatures the CuII complex 1 forms three-center, three-electron C−H···CuII interaction, identified pulse electron paramagnetic resonance spectroscopy supported density functional theory calculations. bond cleavage is coupled with copper oxidation, product 2...

Ultrafast two-dimensional infrared (2D IR) vibrational echo spectroscopy has proven broadly useful for studying molecular dynamics in solutions. Here, we extend the technique to probing interfacial and structure of a silica surface-tethered transition metal carbonyl complex--tricarbonyl (1,10-phenanthroline)rhenium chloride--of interest as photoreduction catalyst. We interpret data using theoretical framework devised separate roles structural evolution excitation transfer inducing spectral...

A new catalyst (see structure) hydroxylates phenols with O2 via a stable side-on peroxide complex, which is similar to the active site of tyrosinase in terms ligand environment and its spectroscopic properties. The catalytic oxidation quinones proceeds at room temperature presence NEt3 even non-native substrates can be oxidized catalytically. reaction mechanism analogous that enzyme-catalyzed reaction.

Azidopropyl functionalized mesoporous silica SBA-15 were prepared with variable azide loadings of 0.03-0.7 mmol g(-1) (~2-50% maximal surface coverage) through a direct synthesis, co-condensation approach. These materials are selectively ethynylated organic moieties copper-catalyzed alkyne cycloaddition (CuAAC) or "click" reaction. Specific loading within material can be regulated by either the limiting reagent relative to loading. The immobilization ferrocene, pyrene,...

Nature's facility with dioxygen outmatches modern chemistry in the oxidation and oxygenation of materials substrates for biosynthesis cellular metabolism. The Earth's most abundant naturally occurring oxidant is-frankly-poorly understood controlled, thus underused. Copper-based enzyme metallocofactors are ubiquitous to efficient consumption by all domains life. Over last several decades, we have joined many research groups study copper- dioxygen-dependent enzymes through close investigation...

Recently a Cu(III)2 bis-μ-oxo dimer ligated by peralkylated amines has been found to interconvert with the side-on peroxo-bridged, μ-η2:η2 isomer. The Cu(III)2(μ-O)2 exhibits two intense charge transfer (CT) features in near-UV region of electronic absorption spectrum. Laser excitation into lower-energy CT band at 25 000 cm-1 results resonance enhancement Raman peaks 609 and 118 which profile this give overtone combination progressions. combined application normal coordinate analysis...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTGalactose Oxidase Model Complexes: Catalytic ReactivitiesYadong Wang and T. D. P. StackView Author Information Department of Chemistry, Stanford University Stanford, California 94305 Cite this: J. Am. Chem. Soc. 1996, 118, 51, 13097–13098Publication Date (Web):December 25, 1996Publication History Received24 June 1996Published online25 December inissue 1 January...

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ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTDifferential Reactivity between Interconvertible Side-On Peroxo and Bis-μ-oxodicopper Isomers Using Peralkylated Diamine LigandsViswanath Mahadevan, Mark J. Henson, Edward I. Solomon, T. D. P. StackView Author Information Department of Chemistry, Stanford University Stanford, California 94305 Cite this: Am. Chem. Soc. 2000, 122, 41, 10249–10250Publication Date (Web):September 30, 2000Publication History Received12 July 2000Published online30...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTC−H Bond Activation by a Ferric Methoxide Complex: A Model for the Rate-Determining Step in Mechanism of LipoxygenaseRobert T. Jonas and D. P. StackView Author Information Department Chemistry, Stanford University Stanford, California 94305-5080 Cite this: J. Am. Chem. Soc. 1997, 119, 36, 8566–8567Publication Date (Web):September 10, 1997Publication History Received9 May 1997Published online10 September inissue 1...