Abstract Oxygenation of copper(I) with tetradentate tripodal ligands (L) comprised a tris(aminoethyl)amine (tren) skeleton having sterically bulky substituent(s) on the terminal nitrogens has been investigated, where L = tris(N-benzylaminoethyl)amine (LH,Bn), tris(N-benzyl-N-methylaminoethyl)amine (LMe,Bn), or tris(N,N-dimethylaminoethyl)amine (LMe,Me). All complexes reacted dioxygen at low temperatures to produce superoxocopper(II) and/or trans-(μ-1,2-peroxo)-dicopper(II) depending steric...

Copper(I)-dioxygen reactivity has been examined using a series of 2-(2-pyridyl)ethylamine bidentate ligands (R1)Py1(R2,R3). The ligand with the methyl substituent on pyridine nucleus (Me)Py1(Et,Bz) (N-benzyl-N-ethyl-2-(6-methylpyridin-2-yl)ethylamine) predominantly provided (mu-eta(2):eta(2)-peroxo)dicopper(II) complex, while without 6-methyl group (H)Py1(Et,Bz) (N-benzyl-N-ethyl-2-(2-pyridyl)ethylamine) afforded bis(mu-oxo)dicopper(III) complex under same experimental conditions. Both...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTA Bis(μ-oxo)dicopper(III) Complex with Aromatic Nitrogen Donors: Structural Characterization and Reversible Conversion between Copper(I) SpeciesHideki Hayashi, Shuhei Fujinami, Shigenori Nagatomo, Seiji Ogo, Masatatsu Suzuki, Akira Uehara, Yoshihito Watanabe, Teizo KitagawaView Author Information Department of Chemistry, Faculty Science Kanazawa University, Kakuma-machi Kanazawa, Ishikawa 920-1192, Japan Institute for Molecular Myodaiji,...

Bis(μ-oxo)dinickel(III) complexes supported by a series of bis[2-(2-pyridyl)ethyl]amine ligands have been successfully generated treating the corresponding bis(μ-hydroxo)dinickel(II) or bis(μ-methoxo)dinickel(II) complex with an equimolar amount H2O2 in acetone at low temperature. The bis(μ-oxo)dinickel(III) exhibit characteristic UV−vis absorption band ∼410 nm and resonance Raman 600−610 cm-1 that shifted to 570−580 upon 18O-substitution. Kinetic studies isotope labeling experiments using...

Profound insights into the catalytic mechanism of galactose oxidase (GO) are offered by new models active form metalloenzyme. The important role Cu(II) center in oxidation benzyl alcohol to benzaldehyde Cu(II)-phenoxyl radical complex ligand 1 has been revealed comparison with reactivity corresponding Zn(II)-phenoxyl complex; py=2-pyridyl.

The first isolation and spectroscopic characterization of the mononuclear hydroperoxo−iron(III) complex [Fe(H2bppa)(OOH)]2+ (2) stoichiometric oxidation substrates by iron−oxo intermediate generated its decomposition have been described. purple species 2 obtained from reaction [Fe(H2bppa)(HCOO)](ClO4)2 with H2O2 in acetone at −50 °C gave characteristic UV−vis (λmax = 568 nm, ε 1200 M-1 cm-1), ESR (g 7.54, 5.78, 4.25, S 5/2), ESI mass spectra (m/z 288.5 corresponding to ion,...

(μ-Hydroxo or oxo)(μ-1,2-peroxo)diiron(III) complexes having a tetradentate tripodal ligand (L) containing carboxylate sidearm [Fe2(μ-OH μ-O)(μ-O2)(L)2]n+ were synthesized as models for peroxo-intermediates of non-heme diiron proteins and characterized by various physicochemical measurements including X-ray analysis, which provide fundamental structural spectroscopic insights into the peroxodiiron(III) complexes.

Spectroscopic properties, amino acid sequence, electron transfer kinetics, and crystal structures of the oxidized (at 1.7 Å resolution) reduced form 1.8 a novel plastocyanin from fern <i>Dryopteris crassirhizoma</i> are presented. Kinetic studies show that of<i>Dryopteris</i> remains redox-active at low pH, under conditions where oxidation other plastocyanins is inhibited by protonation solvent-exposed active site residue, His⁸⁷ (equivalent to His⁹⁰in <i>Dryopteris</i>...

A mononuclear (η2-peroxo)copper(II) complex is observed in the reaction of H2O2 and a copper(II) supported by tridentate pyridylethylamine ligand (see scheme). The formation this unprecedented intermediate species can be followed at −90 °C EPR UV/Vis absorption spectroscopy. Supporting information for article available on WWW under http://www.wiley-vch.de/contents/jc_2002/2002/z19616_s.pdf or from author. Please note: publisher not responsible content functionality any supporting supplied...

A series of the copper(II) complexes with tripodal tetradentate tris(pyridyl 2-methyl)amine-based ligands possessing hydrogen-bonding 6-aminopyridine units (tapa, three amino groups; bapa, two mapa, one group) have been synthesized, and their a small molecule such as dioxygen azide studied spectroscopically structurally. The reaction Cu(II) NaN3 given mononuclear copper in an end-on mode, [Cu(tapa)(N3)]ClO4 (1a), [Cu(bapa)(N3)]ClO4 (2a), [Cu(mapa)(N3)]ClO4 (3a), [Cu(tpa)(N3)]ClO4 (4a) (tpa,...

A novel copper(II)−OOH complex with functional ligand that can form a hydrogen bond the distal oxygen of hydroperoxide has been designed and prepared as structural/functional model dopamine β-hydroxylases, whose spectroscopic characterization decomposition rates have indicated is activated through hydrogen-bonding interaction oxygen.

A novel hydroperoxo-copper(II) complex with a square-planar geometry has been prepared, which exhibited higher selectivity and catalytic reactivity for dimethyl sulfide, in contrast to that trigonal-bipyramidal one.

Oxidizing intermediates are generated from nonheme iron(III) complexes to investigate the electronic structure and reactivity, in comparison with oxoiron(IV) porphyrin π-cation radical (compound I) as a heme enzyme model. Sterically hindered iron salen complexes, bearing fifth ligand Cl (1), OH2 (2), OEt (3), OH (4), oxidized both electrochemically chemically. Stepwise one-electron oxidation of 1 2 generates iron(III)−mono- diphenoxyl radicals, revealed by detailed spectroscopic...

Functional regulation of myoglobin (Mb) is thought to be achieved through the heme environment furnished by nearby amino acid residues, and subtle tuning intrinsic Fe reactivity. We have performed substitution strongly electron-withdrawing perfluoromethyl (CF(3)) group(s) as side chain(s) Mb obtain large alterations electronic structure in order elucidate relationship between O(2) affinity properties peripheral chains. utilized equilibrium constant (pK(a)) "acid-alkaline transition"...

Thermodynamic and diffraction analyses were performed to establish the phase diagram for a binary system between 4-n-nonyl-4′-isothiocyanatobiphenyl (9TCB) n-nonane. The swollen SmE structure is identified in system. Upon swelling, characteristic two-dimensional herringbone array maintained whereas layer spacing of increases with content Considering difficulties explaining experimental findings based on traditional model structure, new model, lamellar two types sublayers consisting aromatic...

This study investigated the pore size dependence of mass transfer zinc myoglobin (ZnMb) in a single mesoporous silica particle through confocal fluorescence microspectroscopy. The ZnMb's depth profile was analyzed by spherical diffusion model, and intraparticle coefficient obtained. with various sizes (10, 15, 30, 50 nm) furthermore based on surface model. Although mechanism all particles followed adsorption desorption ZnMb affected depending size. influence slow became pronounced for large...

Understanding the intraparticle diffusion mechanism within single particles is crucial for processes such as chromatographic separation, drug delivery, and solid extraction. However, when time required to reach distribution equilibrium extremely short (on order of several seconds), conventional kinetic detection methods pose significant challenges in observing behavior. In this study, we employed fluorescence correlation spectroscopy (FCS)─a technique capable detecting behavior at...

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTAliphatic Hydroxylation by a Bis(μ-oxo)dinickel(III) ComplexShinobu Itoh, Hideki Bandoh, Shigenori Nagatomo, Teizo Kitagawa, and Shunichi FukuzumiView Author Information Department of Material Life Science Graduate School Engineering, Osaka University 2-1 Yamada-oka, Suita, 565-0871, Japan Institute for Molecular Myodaiji, Okazaki 444-8585, Cite this: J. Am. Chem. Soc. 1999, 121, 38, 8945–8946Publication Date (Web):September 9,...

Stabilization of a peroxocarbonate ligand by formation five-membered chelate ring. The mononuclear complex 1 was prepared the reaction bis(μ-hydroxo)diiron(III) with H2O2 and CO2. Compound is first crystallographically characterized transition metal ligand. Formation moiety in proceeds nucleophilic addition peroxide anion to Hqn=quinaldic acid.

Phenolate and phenoxyl radical complexes of a series alkaline earth metal ions as well monovalent cations such Na+ K+ have been prepared by using 2,4-di-tert-butyl-6-(1,4,7,10-tetraoxa-13-aza-cyclopentadec-13-ylmethyl)phenol (L1H) 2,4-di-tert-butyl-6-(1,4,7,10,13-pentaoxa-16-aza-cyclooctadec-16-ylmethyl)phenol (L2H) to examine the effects on structure, physicochemical properties redox reactivity phenolate complexes. Crystal structures Mg2+- Ca2+-complexes L1- Ca2+- Sr2+-complexes L2- were...

The appearance of reentrant nematic phase was identified in nCB/8CB (n = 1–6) binary mixtures using differential scanning calorimetry, small-angle X-ray diffraction and polarising microscopy with photomonitor. Phase diagrams can roughly be unified if plotted against the average number alkyl chain length. Distinction recognised for boundaries between smectic A phases even odd n minor component nCB. character 8CB as 'SmA former' is briefly discussed.

The zeta potential (ζ) of a particle is surface charge density (σ)-dependent parameter. If change in σ can be induced by modification, the number molecules modified on detected as measurable ζ. In this study, we demonstrate protein detection at zmol or pM levels (bovine serum albumin (BSA), myoglobin (Mb), and lysozyme (Lyz)) carboxy-functionalized polystyrene (PS) microparticles using ζ change. Protein modification PS particles changes because negatively charged carboxy group used for...

Physicochemical properties of the Cu(II)− and Zn(II)−phenoxyl radical complexes ligand 1H its 2,4-di-tert-butyl derivative 2H have been examined as models for active form galactose oxidase to shed light on role thioether group in novel organic cofactor.

Abstract In order to clarify the effect of hydrogen bonding on stabilities (μ‐peroxo)dicopper complexes with a trans ‐μ‐1,2‐peroxo form, novel copper intramolecular interaction sites have been synthesized, and their spectroscopic properties thermal studied. The selected tripodal tetradentate ligands were tris(2‐pyridylmethyl)amine (TPA) derivatives bearing pivalamido amino groups at 6‐position pyridine ring in TPA, {[6‐(pivalamido)pyrid‐2‐yl]methyl}bis(pyrid‐2‐ylmethyl)amine (MPPA)...