Metal−dioxygen adducts are key intermediates detected in the catalytic cycles of dioxygen activation by metalloenzymes and biomimetic compounds. In this study, mononuclear cobalt(III)−peroxo complexes bearing tetraazamacrocyclic ligands, [Co(12-TMC)(O2)]+ [Co(13-TMC)(O2)]+, were synthesized reacting [Co(12-TMC)(CH3CN)]2+ [Co(13-TMC)(CH3CN)]2+, respectively, with H2O2 presence triethylamine. The isolated characterized various spectroscopic techniques X-ray crystallography, structural...

A new fluorescent zinc sensor (HNBO–DPA) consisting of 2-(2′-hydroxy-3′-naphthyl)benzoxazole (HNBO) chromophore and a di(2-picolyl)amine (DPA) metal chelator has been prepared examined for bioimaging. The probe exhibits zinc-induced fluorescence turn-on without any spectral shifts. Its crystal structure reveals that HNBO–DPA binds ion in pentacoordinative fashion through the DPA HNBO moieties. Steady-state photophysical studies establish deprotonation group. Nanosecond femtosecond laser...

The geometric and electronic structures reactivity of an S = 5/2 (HS) mononuclear nonheme (TMC)Fe(III)-OOH complex are studied by spectroscopies, calculations, kinetics compared with the results previous studies 1/2 (LS) Fe(III)-OOH complexes to understand parallels differences in mechanisms O-O bond homolysis electrophilic H-atom abstraction reactions. reaction HS [(TMC)Fe(III)-OOH](2+) is found involve axial ligand coordination a crossing LS surface for homolysis. Both perform direct...

Lytic polysaccharide monooxygenases have received significant attention as catalytic convertors of biomass to biofuel. Recent studies suggest that its peroxygenase activity (i.e., using H

Metal-superoxo intermediates have been invoked as reactive species in C-H bond cleavage of substrates by oxygenase enzymes. In this work, we shown the first structurally characterized end-on chromium(III)-superoxo complex, [Cr(III)(14-TMC)(O(2))(Cl)](+), which was synthesized reacting [Cr(II)(14-TMC)(Cl)](+) with O(2). The Cr(III)-superoxo intermediate has reactivities alkylaromatics via a H-atom abstraction mechanism.

The dark side of the Mn: A manganese(III) complex bearing a 13-membered macrocyclic ligand (1, see picture) binds peroxo in side-on eta(2) fashion. reactivity 1 is influenced by introduction anionic ligands trans to group. Electronic and structural changes upon trans-ligand binding explain increased nucleophilicity resulting complexes 1-X.

Mononuclear nonheme iron(IV)-oxo complexes with two different topologies, cis-α-[Fe(IV)(O)(BQCN)](2+) and cis-β-[Fe(IV)(O)(BQCN)](2+), were synthesized characterized various spectroscopic methods. The effect of ligand topology on the reactivities was investigated in C-H bond activation oxygen atom-transfer reactions; more reactive than cis-β-[Fe(IV)(O)(BQCN)](2+) oxidation reactions. reactivity difference between cis-α cis-β isomers [Fe(IV)(O)(BQCN)](2+) rationalized Fe(IV/III) redox...

Give me an "O"! Mononuclear nonheme iron(IV) oxo complexes have been generated using water as oxygen source and cerium(IV) oxidant. The high-yield oxygenation of organic substrates in this system (see picture, Fe green, O red, N blue, C gray) is catalyzed by iron(II) complexes. the oxygenated products has assigned unambiguously isotopic labeling experiments.

Mononuclear metal-dioxygen adducts, such as metal-superoxo and -peroxo species, are generated key intermediates in the catalytic cycles of dioxygen activation by heme non-heme metalloenzymes. We have shown recently that geometric electronic structure Ni–O2 core [Ni(n-TMC)(O2)]+ (n = 12 14) varies depending on ring size supporting TMC ligand. In this study, mononuclear Ni(II)-superoxo Ni(III)-peroxo complexes bearing a common macrocylic 13-TMC ligand, [NiII(13-TMC)(O2)]+ [NiIII(13-TMC)(O2)]+,...

The source of the problem: Experiments with isotopically labeled water can be used to unambiguously assign oxygen in a nonheme manganese(IV) oxo complex. complex, which was generated using as an and cerium(IV) oxidant (see picture), shows reactivities activation CH bonds alkyl-functionalized aromatic molecules oxidation substrates (sub) benzyl alcohol. Detailed facts importance specialist readers are published "Supporting Information". Such documents peer-reviewed, but not copy-edited or...

Redox-inactive metal ions that function as Lewis acids play pivotal roles in modulating reactivities of oxygen-containing complexes a variety biological and biomimetic reactions, including dioxygen activation/formation functionalization organic substrates. Mononuclear nonheme iron(III)-peroxo species are invoked active oxygen intermediates the catalytic cycles activation by iron enzymes their compounds. Here, we report mononuclear binding redox-inactive ions, [(TMC)FeIII(O2)]+-M3+ (M3+ =...

The four-electron reduction of dioxygen by decamethylferrocene (Fc*) to water is efficiently catalyzed a binuclear copper(II) complex (1) and mononuclear (2) in the presence trifluoroacetic acid acetone at 298 K. Fast electron transfer from Fc* 1 2 affords corresponding Cu(I) complexes, which react low temperature (193 K) with afford η(2):η(2)-peroxo dicopper(II) (3) bis-μ-oxo dicopper(III) (4) intermediates, respectively. rate constants for octamethylferrocene (Me(8)Fc) as well Me(8)Fc 3...

We report the first direct experimental evidence showing that a high-spin iron(III)-hydroperoxo complex bearing an N-methylated cyclam ligand can oxidize thioanisoles. DFT calculations showed reaction pathway involves heterolytic O-O bond cleavage and choice of versus homolytic is dependent on spin state number electrons in d(xz) orbital Fe(III)-OOH species.

An amyloidogenic peptide, amyloid-β (Aβ), has been implicated as a contributor to the neurotoxicity of Alzheimer's disease (AD) that continues present major socioeconomic burden for our society. Recently, use metal complexes capable cleaving peptides arisen an efficient tactic amyloid management; unfortunately, little reported pursue this strategy. Herein, we report novel approach validate hydrolytic cleavage divalent toward two isoforms Aβ (Aβ40 and Aβ42) tune their proteolytic activity...

A new fluorescence turn-on probe that responds exclusively to H2O2 exhibits subcellular localized staining of lysosomes.

The O(2) and NO reactivity of a Cr(II) complex bearing 12-membered tetraazamacrocyclic N-tetramethylated cyclam (TMC) ligand, [Cr(II)(12-TMC)(Cl)](+) (1), the its peroxo derivative, [Cr(IV)(12-TMC)(O(2))(Cl)](+) (2), are described. By contrast to previously reported Cr(III)-superoxo complex, [Cr(III)(14-TMC)(O(2))(Cl)](+), Cr(IV)-peroxo 2 is formed in reaction 1 O(2). Full spectroscopic X-ray analysis revealed that possesses side-on η(2)-peroxo ligation. quantitative with affords reduction...

Metal–superoxo species are believed to play key roles in oxygenation reactions by metalloenzymes. One example is cysteine dioxygenase (CDO) that catalyzes the oxidation of with O2, and an iron(III)–superoxo proposed as intermediate effects sulfoxidation reaction. We now report first biomimetic showing a chromium(III)–superoxo complex bearing macrocyclic TMC ligand, [CrIII(O2)(TMC)(Cl)]+, active oxidant oxygen atom transfer (OAT) reactions, such phosphine sulfides. The electrophilic character...

A Cr(V)-oxo complex bearing a macrocyclic TMC ligand, [CrV(TMC)(O)(OCH3)]2+, was synthesized, isolated, and characterized by various physicochemical methods, including UV-vis, ESI-MS, resonance Raman, EPR X-ray analysis. The reactivity of the investigated in C–H O–H bond activation reactions. Cr(III)-superoxo complex, [CrIII(TMC)(O2)(Cl)]+, reactions as well. By comparing reactivities complexes under identical reaction conditions, we were able to demonstrate that is more reactive than bonds....

We report the first example of a mononuclear nonheme manganese(III)-hydroperoxo complex derived from protonation an isolated manganese(III)-peroxo bearing N-tetramethylated cyclam (TMC) ligand, [Mn(III)(TMC)(OOH)](2+). The Mn(III)-hydroperoxo intermediate is characterized with various spectroscopic methods as well density functional theory (DFT) calculations, showing binding hydroperoxide ligand in end-on fashion. species competent oxidant oxygen atom transfer (OAT) reactions, such oxidation...