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1.
Radosaw Kotuniak Marc J. F. Strampraad Karolina Bossak‐Ahmad Urszula E. Wawrzyniak Iwona Ufnalska Peter‐Leon Hagedoorn Wojciech Bal 《Angewandte Chemie (International ed. in English)》2020,59(28):11234-11239
The amino‐terminal copper and nickel/N‐terminal site (ATCUN/NTS) present in proteins and bioactive peptides exhibits high affinity towards CuII ions and have been implicated in human copper physiology. Little is known, however, about the rate and exact mechanism of formation of such complexes. We used the stopped‐flow and microsecond freeze‐hyperquenching (MHQ) techniques supported by steady‐state spectroscopic and electrochemical data to demonstrate the formation of partially coordinated intermediate CuII complexes formed by glycyl–glycyl–histidine (GGH) peptide, the simplest ATCUN/NTS model. One of these novel intermediates, characterized by two‐nitrogen coordination, t1/2≈100 ms at pH 6.0 and the ability to maintain the CuII/CuI redox pair is the best candidate for the long‐sought reactive species in extracellular copper transport. 相似文献
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Radosław Kotuniak Marc J. F. Strampraad Karolina Bossak-Ahmad Dr. Urszula E. Wawrzyniak Iwona Ufnalska Dr. Peter-Leon Hagedoorn Prof. Wojciech Bal 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(28):11330-11335
The amino-terminal copper and nickel/N-terminal site (ATCUN/NTS) present in proteins and bioactive peptides exhibits high affinity towards CuII ions and have been implicated in human copper physiology. Little is known, however, about the rate and exact mechanism of formation of such complexes. We used the stopped-flow and microsecond freeze-hyperquenching (MHQ) techniques supported by steady-state spectroscopic and electrochemical data to demonstrate the formation of partially coordinated intermediate CuII complexes formed by glycyl–glycyl–histidine (GGH) peptide, the simplest ATCUN/NTS model. One of these novel intermediates, characterized by two-nitrogen coordination, t1/2≈100 ms at pH 6.0 and the ability to maintain the CuII/CuI redox pair is the best candidate for the long-sought reactive species in extracellular copper transport. 相似文献
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Clifton L. Wagner Dr. Lizhi Tao Emily J. Thompson Dr. Troy A. Stich Dr. Jingdong Guo Dr. James C. Fettinger Prof. Louise A. Berben Prof. R. David Britt Prof. Shigeru Nagase Prof. Philip P. Power 《Angewandte Chemie (International ed. in English)》2016,55(35):10444-10447
The synthesis of the first linear coordinated CuII complex Cu{N(SiMe3)Dipp}2 ( 1 Dipp=C6H5‐2,6Pri2) and its CuI counterpart [Cu{N(SiMe3)Dipp}2]? ( 2 ) is described. The formation of 1 proceeds through a dispersion force‐driven disproportionation, and is the reaction product of a CuI halide and LiN(SiMe3)Dipp in a non‐donor solvent. The synthesis of 2 is accomplished by preventing the disproportionation into 1 by using the complexing agent 15‐crown‐5. EPR spectroscopy of 1 provides the first detailed study of a two‐coordinate transition‐metal complex indicating strong covalency in the Cu?N bonds. 相似文献
5.
Craig A. Bell Paul V. Bernhardt Prof. Lawrence R. Gahan Prof. Manuel Martínez Prof. Michael J. Monteiro Prof. Carlos Rodríguez Clint A. Sharrad Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(10):3166-3175
The potentially hexadentate mixed‐donor cage ligand 1‐methyl‐8‐amino‐3,13,16‐trithia‐6,10,19‐triazabicyclo[6.6.6]eicosane (AMME‐N3S3sar; sar=sarcophagine) displays variable coordination modes in a complex with copper(II). In the absence of coordinating anions, the ligand adopts a conventional hexadentate N3S3 binding mode in the complex [Cu(AMME‐N3S3sar)](ClO4)2 that is typical of cage ligands. This structure was determined by X‐ray crystallography and solution spectroscopy (EPR and NIR UV/Vis). However, in the presence of bromide ions in DMSO, clean conversion to a five‐coordinate bromido complex [Cu(AMME‐N3S3sar)Br]+ is observed that features a novel tetradentate (N2S2)‐coordinated form of the cage ligand. This copper(II) complex has also been characterized by X‐ray crystallography and solution spectroscopy. The mechanism of the reversible interconversion between the six‐ and five‐coordinated copper(II) complexes has been studied and the reaction has been resolved into two steps; the rate of the first is linearly dependent on bromide ion concentration and the second is bromide independent. Electrochemistry of both [Cu(AMME‐N3S3sar)]2+ and [Cu(AMME‐N3S3sar)Br]+ in DMSO shows that upon reduction to the monovalent state, they share a common five‐coordinated form in which the ligand is bound to copper in a tetradentate form exclusively, regardless of whether a six‐ or five‐coordinated copper(II) complex is the precursor. 相似文献
6.
Vera V. Khrizanforova Robert R. Fayzullin Vladimir I. Morozov Ildar F. Gilmutdinov Anton N. Lukoyanov Olga N. Kataeva Tatiana P. Gerasimova Sergey A. Katsyuba Igor L. Fedushkin Konstantin A. Lyssenko Yulia H. Budnikova 《化学:亚洲杂志》2019,14(17):2979-2987
New nickel‐based complexes of 1,2‐bis[(2,6‐diisopropylphenyl)imino]acenaphthene (dpp‐bian) with BF4? counterion or halide co‐ligands were synthesized in THF and MeCN. The nickel(I) complexes were obtained by using two approaches: 1) electrochemical reduction of the corresponding nickel(II) precursors; and 2) a chemical comproportionation reaction. The structural features and redox properties of these complexes were investigated by using single‐crystal X‐ray diffraction (XRD), cyclic voltammetry (CV), and electron paramagnetic resonance (EPR) and UV/Vis spectroscopy. The influence of temperature and solvent on the structure of the nickel(I) complexes was studied in detail, and an uncommon reversible solvent‐induced monomer/dimer transformation was observed. In the case of the fluoride complex, the unpaired electron was found to be localized on the dpp‐bian ligand, whereas all of the other nickel complexes contained neutral dpp‐bian moieties. 相似文献
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Structural Interactions of Planar and Non‐planar Bis(1,2‐dithiosquarato)metalate Host Lattices with CuII Complexes – Structure and EPR Investigations 1,2‐Dithiosquaratometalates (M = Cu, Ni, Zn) are available by direct synthesis from metal salts with dipotassium‐1,2‐dithiosquarate. The structural influence of the planar and nonplanar host lattice systems (BzlEt3N)2[Cu/Ni(dtsq)2] and (BzlEt3N)2[Cu/Zn(dtsq)2] on the geometrical and electronic structure of the CuII guest complex [Cu(dtsq)2]2– is studied by EPR spectroscopy. The used host lattices (BzlEt3N)2[Ni(dtsq)2] (planar) and (BzlEt3N)2[Zn(dtsq)2] (tetrahedral) are characterized by X‐ray structure analysis. (BzlEt3N)2[Ni(dtsq)2] crystallizes in the triclinic unit cell P1 with a = 9.1021(8) Å, b = 9.4190(8) Å, c = 11.0119(10) Å, α = 92.8560(10)°, β = 95.375(2)°, γ = 104.5180(10)° and Z = 1. (BzlEt3N)2[Zn(dtsq)2] crystallizes in the monoclinic unit cell C2/c with a = 21.1299(14) Å, b = 16.6641(11) Å, c = 13.8324(9) Å, β = 123.9100(10)° and Z = 4. The g and A Cu tensors in the Cu/Ni system are nearly axial symmetric (g|| = 2.122, g⊥ = 2.028; A = –159.5 · 10–4 cm–1, A = –36.9 · 10–4 cm–1). The coordination geometry of the CuII guest complex in the tetrahedral Cu/Zn system is rather distorted, which is shown by the changed g and A Cu tensor parameters (g|| = 2.143, g⊥ = 2.042; A = –103.0 · 10–4 cm–1, A ≈ –5.0 · 10–4 cm–1). The spin density distribution is discussed using EHT molecular orbital calculations. 相似文献
9.
Introduction of a Fluorescent Probe to Amyloid‐β to Reveal Kinetic Insights into Its Interactions with Copper(II) 下载免费PDF全文
Thomas Branch Paul Girvan Prof. Mauricio Barahona Dr. Liming Ying 《Angewandte Chemie (International ed. in English)》2015,54(4):1227-1230
The kinetics of the interactions between amyloid‐β (Aβ) and metal ions are crucial to understanding the physiological and pathological roles of Aβ in the normal brain and in Alzheimer’s disease. Using the quenching of a fluorescent probe by Cu2+, the mechanism of Aβ/Cu2+ interactions in physiologically relevant conditions has been elucidated. Cu2+ binds to Aβ at a near diffusion‐limited rate, initially forming component I. The switching between component I and II occurs on the second timescale, with a significant energy barrier. Component I is much more reactive towards Cu2+ ligands and likely responsible for initial Aβ dimer formation. Clioquinol (CQ) is shown to sequester Cu2+ more effectively than other tested ligands. These findings have implications for the potential roles of Aβ in regulating neurotransmission, and for the screening of small molecules targeting Aβ–metal interactions. 相似文献
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Two new complexes: [Cu(TBZ)(bipy)Cl]Cl·H2O ( 1 ) and [Cu(TBZ)(phen)Cl]Cl·H2O ( 2 ) [TBZ=2‐(4′‐thiazolyl)‐ benzimidazole, phen=1,10‐phenanthroline and bipy=2,2′‐bipyridine] have been synthesized and characterized by elemental analysis, molar conductivity, IR, and UV‐vis methods. Complex 2 , structurally characterized by single‐crystal X‐ray crystallography, crystallizes in the monoclinic space group P21/c in a unit cell of a=0.85257(12) nm, b=2.5358(4) nm, c=1.15151(13) nm, β=118.721(8)°, V=2.183.2(5) nm3, Z=4, Dc=1.624 g·cm−3, µ=1.367 mm−1. The complexes, free ligands and chloride copper(II) salt were each tested for their ability to inhibit the growth of two gram‐positive (B. subtilis and S. aureus) and two gram‐negative (Salmonella and E. coli) bacteria. The complexes showed good antibacterial activities against the microorganisms. The interaction between the complexes and calf thymus DNA in aqueous solution was investigated adopting electronic absorption spectroscopy, fluorescence spectroscopy, viscosity measurements and cyclic voltammetry. Results suggest that the two complexes can bind to DNA by intercalative mode. In addition, the result of agarose gel electrophoresis suggested that the complexes can cleave the plasmid DNA at physiological pH and room temperature. Mechanistic studies with different inhibiting reagents reveal that hydroxyl radicals, and a singlet oxygen‐like copper‐oxo species are all involved in the DNA scission process mediated by the complexes. 相似文献
11.
Wilfredo Hernndez Evgenia Spodine Andres Vega Rainer Richter Jan Griebel Reinhard Kirmse Uwe Schrder Lothar Beyer 《无机化学与普通化学杂志》2004,630(10):1381-1386
The N‐acyl thiourea complexes bis[N,N‐diethyl‐N′‐(p‐nitrobenzoyl)‐thioureato]copper(II) ( 1a,1b ) and bis(N,N‐diphenyl‐N′‐benzoylthioureato)copper(II) ( 2a,2b ) crystallize in each case in two modifications. X‐ray structural analysis shows that 1a and 1b are cis‐trans isomers. This is very unusual for N‐acyl thioureato complexes because with exception of one platinum(II) complex up to now only cis complexes have been found. In contrast X‐ray structural analysis of both forms 2a and 2b of the other complex shows no cis‐trans pair. Both modifications are cis complexes. In solution both isomers of the copper(II) complexes are observable by EPR spectroscopy. 相似文献
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Six new macrocyclic complexes were synthesized by a template reaction of 1,4-bis(2-formylphenoxy)butane with diamines and Cu(NO3)2·3H2O and their structures were proposed on the basis of elemental analysis, FT-IR, UV-Vis, magnetic susceptibility measurements, molar conductivity measurements and mass spectra. The metal to ligand molar ratios of the Cu(Ⅱ) complexes were found to be 1 : 1. The Cu(Ⅱ) complexes are 1 : 2 electrolytes as shown by their molar conductivities (∧m) in DMF at 10^-3 mol·L^-1. Due to the existence of free ions the Cu(Ⅱ) complexes are electrically conductive. Their configurations were proposed to be probably distorted octahedral. 相似文献
13.
Long Yang Ralf Steinbock Alexej Scheremetjew Rositha Kuniyil Lars H. Finger Antonis M. Messinis Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2020,59(27):11130-11135
A ruthenium‐catalyzed electrochemical dehydrogenative annulation reaction of imidazoles with alkynes has been established, enabling the preparation of various bridgehead N‐fused [5,6]‐bicyclic heteroarenes through regioselective electrochemical C?H/N?H annulation without chemical metal oxidants. Novel azaruthenabicyclo[3.2.0]heptadienes were fully characterized and identified as key intermediates. Mechanistic studies are suggestive of an oxidatively induced reductive elimination pathway within a ruthenium(II/III) regime. 相似文献
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Three new μ‐oxamido‐bridged heterodinuclear copper (II)‐chromium (III) complexes formulated [Cu(Me2oxpn)Cr‐(L)2](NO3)3, where Me2oxpn denotes N,N'‐bis(3‐amino‐2, 2‐dimethylpropyl)oxamido dianion and L represents 5‐methyl‐1,10‐phenanthroline (Mephen), 4,7‐diphenyl‐1,10‐phenanthroline (Ph2phen) or 2,2′‐bipyridine (bpy), have been synthesized and characterized by elemental analyses, IR and electronic spectral studies, magnetic moments of room‐temperature and molar conductivity measurements. It is proposed that these complexes have oxamido‐bridged structures consisting of planar copper (II) and octahedral chromium (III) ions. The variable temperature magnetic susceptibilities (4.2–300 K) of complexes [Cu(Me2oxpn)Cr(Ph2phen)2](NO3)3 (1) and [Cu(Me2oxpn)Cr(Mephen)2] (NO3)3 (2) were further measured and studied, demonstrating the ferromagnetic interaction between the adjacent chromium (III) and copper (II) ions through the oxamido‐bridge in both complexes 1 and 2. Based on the spin Hamiltonian, ? = ‐ 2J?1 · ?2, the exchange integrals J were evaluated as + 21.5 an?1 for 1 and + 22.8 cm?1 for 2. 相似文献
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Two novel supramolecular complexes [Cu(bpapa)(dhbd)]·CHaOH (1) and [Cu(bpapa)(ma)]·ma (2) (bpapa= bis[6-(2-pyridylamino)pyrid-2-yl]amine, dhbd=2,3-dihydroxybutanedioate dianion, ma=a-methacrylate) were rationally designed, synthesized and characterized by single crystal X-ray diffraction, IR, electronic spectroscopy and thermogravimetric analyses. Complex 1 was the first oligo-a-pyfidylamino complex based on hydroxypolycarboxylate and self-assembled into a 3D honeycomb configuration network with open channels and tubes containing 1D ladder-shaped double chains formed by hydrogen bonds and aromatic π-π stacking interactions. Complex 2 constructed a 2D supramolecular network extended by 1D chains from dimeric supramolecular synthon through noncovalent supramolecular interactions. In the two complexes, the chelating monohelical ligand adopted all-anti configuration. Density functional theory calculations were applied to 1 and 2. 相似文献
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EPR and spectrophotometric study on the products of ligand‐exchange taking place on mixing bis(diethyldiselenocarbamato)copper(II), [Cu(Et2dsc)2], and bis(diethyldithiocarbamato)copper(II), [Cu(Et2dtc)2], solutions is reported. EPR spectra monitored at room temperature for one month period reveal a stable equilibrium among the parents (chromophores CuS4 and CuSe4) and the obtained mixed‐chelate [Cu(Et2dtc)(Et2dsc)] complex (chromophore CuS2Se2) in heptane, hexane, benzene, toluene, acetone, DMFA, DMSO and dichloromethane. In CCl4 and CHCl3 two new additional EPR spectra appear attributed to the mixed‐chelate complexes with the chromophores CuSSe3 and CuS3Se which are not observed with electronic spectroscopy. The intensities of all five EPR spectra decrease with the time. It is assumed that the new mixed‐chelates observed in CCl4 and CHCl3 are obtained in a reaction of [Cu(Et2dtc)(Et2dsc)] or [Cu(Et2dtc)2] with the ester of diselenocarbamic acid which is formed in a parallel reaction of [Cu(dsc)2]with CCl4 or CHCl3. 相似文献
18.
Rituparna Biswas Yumi Ida Dr. Michael L. Baker Saptarshi Biswas Paramita Kar Prof. Dr. Hiroyuki Nojiri Prof. Dr. Takayuki Ishida Prof. Dr. Ashutosh Ghosh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(12):3943-3953
Three new trinuclear nickel (II) complexes with the general composition [Ni3L3(OH)(X)](ClO4) have been prepared in which X=Cl? ( 1 ), OCN? ( 2 ), or N3? ( 3 ) and HL is the tridentate N,N,O donor Schiff base ligand 2‐[(3‐dimethylaminopropylimino)methyl]phenol. Single‐crystal structural analyses revealed that all three complexes have a similar Ni3 core motif with three different types of bridging, namely phenoxido (μ2 and μ3), hydroxido (μ3), and μ2‐Cl ( 1 ), μ1,1‐NCO ( 2 ), or μ1,1‐N3 ( 3 ). The nickel(II) ions adopt a compressed octahedron geometry. Single‐crystal magnetization measurements on complex 1 revealed that the pseudo‐three‐fold axis of Ni3 corresponds to a magnetic easy axis, being consistent with the magnetic anisotropy expected from the coordination structure of each nickel ion. Temperature‐dependent magnetic measurements indicated ferromagnetic coupling leading to an S=3 ground state with 2J/k=17, 17, and 28 K for 1 , 2 , and 3 , respectively, with the nickel atoms in an approximate equilateral triangle. The high‐frequency EPR spectra in combination with spin Hamiltonian simulations that include zero‐field splitting parameters DNi/k=?5, ?4, and ?4 K for 1 , 2 , and 3 , respectively, reproduced the EPR spectra well after a anisotropic exchange term was introduced. Anisotropic exchange was identified as Di,j/k=?0.9, ?0.8, and ?0.8 K for 1 , 2 , and 3 , respectively, whereas no evidence of single‐ion rhombic anisotropy was observed spectroscopically. Slow relaxation of the magnetization at low temperatures is evident from the frequency‐dependence of the out‐of‐phase ac susceptibilities. Pulsed‐field magnetization recorded at 0.5 K shows clear steps in the hysteresis loop at 0.5–1 T, which has been assigned to quantum tunneling, and is characteristic of single‐molecule magnets. 相似文献
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Tetrakis(1‐adamantylcarboxylato)dicopper(II) Cu2(1‐Ad)4 – Synthesis, Structure and X‐/Q‐band EPR Investigations The synthesis and the crystal structure of tetrakis(1‐adamantylcarboxylato)dicopper(II) are reported. [Cu2(1‐Ad)4·2DMF] ( 1 , 1‐Ad = adamantylcarboxylate) crystallizes in the space group (Z = 2) with two crystallographically distinguishable complexes in the unit cell. The averaged Cu‐Cu distance of 260.5 pm is smaller than that found for Cu2(ac)4·2H2O. The combination of temperature‐dependent X‐ and Q‐band powder EPR investigations in the temperature range 6 ≤ T ≤ 295 K show the presence of an antiferromagnetically coupled Cu‐Cu dimer and allow a precise determination of the spin‐Hamiltonian parameter. A comparison of those with that derived for Cu2(ac)4·2H2O indicate a higher symmetry within the Cu2O8 central unit of [Cu2(1‐Ad)4·2DMF]. 相似文献
20.
Maji T. K. Das D. Sain S. Ray Chaudhuri N. 《Journal of Thermal Analysis and Calorimetry》2002,68(1):319-328
CuL2C4O4 [L=ethane-1,2-diamine (en)], CuL2C4O4⋅2H2O [L=N-methylethane-1,2-diamine (meen), N-ethylethane-1,2-diamine (eten),N-propylethane-1,2-diamine (pren), N-methyl-N’-ethylethane-
1,2-diamine (meeten) andpropane-1,2-diamine (pn)], CuL2C4O4⋅0.5H2O [L=N,N’-dimethylethane- 1,2-diamine (dmeen)], CuL2C4O4⋅4H2O [L=propane-1,2-diamine (pn)]and CuL2C4O4⋅H2O[L=2-methylpropane-1,2-diamine (ibn)] have been synthesized by the addition of respective diamine to finely powdered CuC4O4⋅2H2O and their thermal studies have been carried out in the solid state. Cu(en)2C4O4 upon heating loses one molecule of diamine with shar pcolour change yielding Cu(en)C4O4 which upon further heating transforms to unidentified products. All aquated-bis-diamine species [CuL2C4O4⋅2H2O, CuL2C4O4⋅0.5H2O and CuL2C4O4⋅H2O] upon heating undergo deaquation–anation reaction in the solid state showing thermochromism and transform to CuL2C4O4, which revert on exposure to humid atmosphere (RH ∼90%). All the squarato bis-diamine species, CuL2C4O4, on further heating transform to unidentified products through the formation of CuLC4O4 as intermediates. The mono diamine species, have been isolated pyrolytically in the solid state and can be stored in a desiccator
as well as in open atmosphere. They are proposed to be polymeric.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献