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Copper type ii EPR

Dmitri V Konarev, Sergey I Troyanov, Alexey V Kuzmin, Yoshiaki Nakano, Manabu Ishikawa, Maxim A Faraonov, Salavat S Khasanov, Alexey L Litvinov, Akihiro Otsuka, Hideki Yamochi, Gunzi Saito, Rimma N Lyubovskaya
Crystalline anionic salts with copper octafluoro- and hexadecafluorophthalocyanines, (Bu4N(+))2[Cu(II)(F8Pc)(4-)](2-)·2C6H4Cl2 (1) and (PPN(+))3[CuF16Pc]3(3-)·2C6H5CN (2), where PPN(+) is bis(triphenylphosphoranylidene)ammonium and Pc is phthalocyanine, have been obtained. The absence of noticeable absorption in the NIR range and DFT calculations for 1 indicate that both negative charges are mainly localized on the Pc ligand, and that the [Cu(II)(F8Pc)(4-)](2-) dianions are formed without reduction of Cu(II)...
February 20, 2017: Inorganic Chemistry
Kathleen E Prosser, Stephanie W Chang, Felix Saraci, Phuc H Le, Charles J Walsby
The Cu(II) complex CuCl2(pbzH), pbzH=2-(2-pyridyl)benzimidazole, and derivatives modified at the non-coordinated nitrogen of the benzimidazole fragment, have been studied as anticancer agents. These compounds show promising cytotoxicity against A549 adenocarcinomic alveolar basal epithelial cells with IC50 values in the range of 5-10μM. Importantly, this activity is higher than either CuCl2·2H2O or the individual ligands, demonstrating that ligand coordination to the Cu(II) centres of the complexes is required for full activity...
February 2017: Journal of Inorganic Biochemistry
Dwaipayan Dutta Gupta, Dandamudi Usharani, Shyamalava Mazumdar
Three stable copper complexes of peptides derived from the copper ion binding loop of the subunit II of cytochrome c oxidase have been prepared and characterized by various spectroscopic techniques. These stable copper complexes of peptides were found to exhibit cysteine, histidine and/or methionine ligation, which has predominant σ-contribution in the Cys-Cu charge transfer. The copper(ii) peptide complexes showed type-2 EPR spectra, which is uncommon in copper-cysteinate complexes. UV-visible spectra, Raman and EPR results support a tetragonal structure of the coordination geometry around the copper ion...
October 17, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Nenad Joksimović, Dejan Baskić, Suzana Popović, Milan Zarić, Marijana Kosanić, Branislav Ranković, Tatjana Stanojković, Sladjana B Novaković, Goran Davidović, Zorica Bugarčić, Nenad Janković
A serie of novel square pyramidal copper(ii) complexes [Cu(L)2H2O] (3a-d) with O,O-bidentate ligands [L = ethyl-2-hydroxy-4-aryl-4-oxo-2-butenoate; aryl = 3-methoxyphenyl-2a, (E)-2-phenylvinyl-2b, (E)-2-(4'-hydroxy-3'-methoxyphenyl)vinyl-2c, 3-nitrophenyl-2d, 2-thienyl-2e] were synthesized and characterized by spectral (UV-Vis, IR, ESI-MS and EPR), elemental and X-ray analysis. The antimicrobial activity was estimated by the determination of the minimal inhibitory concentration (MIC) using the broth microdilution method...
September 27, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Carolina Sánchez-López, Rodrigo Cortés-Mejía, Marco C Miotto, Andres Binolfi, Claudio O Fernández, Jorge M Del Campo, Liliana Quintanar
Human islet amyloid polypeptide (hIAPP) is the major component of amyloid deposits found in pancreatic β-cells of patients with type 2 diabetes (T2D). Copper ions have an inhibitory effect on the amyloid aggregation of hIAPP, and they may play a role in the etiology of T2D. However, deeper knowledge of the structural details of the copper-hIAPP interaction is required to understand the molecular mechanisms involved. Here, we performed a spectroscopic study of Cu(II) binding to hIAPP and several variants, using electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), electronic absorption, and circular dichroism (CD) in the UV-vis region in combination with Born-Oppenheimer molecular dynamics (BOMD) and density functional theory geometry optimizations...
October 5, 2016: Inorganic Chemistry
A Haleel, D Mahendiran, V Veena, N Sakthivel, A Kalilur Rahiman
A series of heteroleptic mononuclear copper(II) complexes of the type [Cu(L(1-3))(diimine)]ClO4 (1-6) containing three tetrazolo[1,5-a]pyrimidine core ligands, ethyl 5-methyl-7-(2-hydroxyphenyl)-4,7-dihydrotetrazolo[1,5-a]pyrimidine-6-carboxylate (HL(1)), ethyl 5-methyl-7-(4-diethylamino-2-hydroxyphenyl)-4,7-dihydrotetrazolo[1,5-a]pyrimidine-6-carboxylate (HL(2)) or ethyl 5-methyl-7-(2-hydroxy-4-nitrophenyl)-4,7-dihydrotetrazolo[1,5-a]pyrimidine-6-carboxylate (HL(3)), and two diimine coligands, 2,2'-bipyridyl (bpy) or 1,10-phenanthroline (phen) have been synthesized and characterized by spectral methods...
November 1, 2016: Materials Science & Engineering. C, Materials for Biological Applications
María S Islas, Alicia Luengo, Carlos A Franca, Mercedes Griera Merino, Laura Calleros, Manuel Rodriguez-Puyol, Luis Lezama, Evelina G Ferrer, Patricia A M Williams
The coordination compound of the antihypertensive ligand irbesartan (irb) with copper(II) (CuIrb) was synthesized and characterized by FTIR, FT-Raman, UV-visible, reflectance and EPR spectroscopies. Experimental evidence allowed the implementation of structural and vibrational studies by theoretical calculations made in the light of the density functional theory (DFT). This compound was designed to induce structural modifications on the ligand. No antioxidant effects were displayed by both compounds, though CuIrb behaved as a weak 1,1-diphenyl-2-picrylhydrazyl radical (DPPH(·)) scavenger (IC50 = 425 μM)...
October 2016: Journal of Biological Inorganic Chemistry: JBIC
Antonio Magrì, Diego La Mendola, Vincenzo Giuseppe Nicoletti, Giuseppe Pappalardo, Enrico Rizzarelli
Type-2 diabetes (T2D) is considered to be a potential threat on a global level. Recently, T2D has been listed as a misfolding disease, such as Alzheimer's and Parkinson's diseases. Human islet amyloid polypeptide (hIAPP) is a molecule cosecreted in pancreatic β cells and represents the main constituent of an aggregated amyloid found in individuals affected by T2D. The trace-element serum level is significantly influenced during the development of diabetes. In particular, the dys-homeostasis of Cu(2+) ions may adversely affect the course of the disease...
September 5, 2016: Chemistry: a European Journal
Ying Lian Qin, Bin Wu Yang, Gao Feng Wang, Hong Sun
Square-planar complexes are commonly formed by transition metal ions having a d(8) electron configuration. Planar cyanometallate anions have been used extensively as design elements in supramolecular coordination systems. In particular, square-planar tetracyanometallate(II) ions, i.e. [M(CN)4](2-) (M(II) = Ni, Pd or Pt), are used as good building blocks for bimetallic Hofmann-type assemblies and their analogues. Square-planar tetracyanonickellate(II) complexes have been extensively developed with N-donor groups as additional co-ligands, but studies of these systems using O-donor ligands are scarce...
July 1, 2016: Acta Crystallographica. Section C, Structural Chemistry
Parisa Hosseinzadeh, Shiliang Tian, Nicholas M Marshall, James Hemp, Timothy Mullen, Mark J Nilges, Yi-Gui Gao, Howard Robinson, David A Stahl, Robert B Gennis, Yi Lu
Mononuclear cupredoxin proteins usually contain a coordinately saturated type 1 copper (T1Cu) center and function exclusively as electron carriers. Here we report a cupredoxin isolated from the nitrifying archaeon Nitrosopumilus maritimus SCM1, called Nmar1307, that contains a T1Cu center with an open binding site containing water. It displays a deep purple color due to strong absorptions around 413 nm (1880 M(-1) cm(-1)) and 558 nm (2290 M(-1) cm(-1)) in the UV-vis electronic spectrum. EPR studies suggest the protein contains two Cu(II) species of nearly equal population, one nearly axial, with hyperfine constant A∥ = 98 × 10(-4) cm(-1), and another more rhombic, with a smaller A∥ value of 69 × 10(-4) cm(-1)...
May 25, 2016: Journal of the American Chemical Society
Tiago A Fernandes, Carla I M Santos, Vânia André, Julia Kłak, Marina V Kirillova, Alexander M Kirillov
Three novel water-soluble 2D copper(II) coordination polymers-[{Cu2(μ2-dmea)2(H2O)}2(μ4-pma)]n·4nH2O (1), [{Cu2(μ2-Hedea)2}2(μ4-pma)]n·4nH2O (2), and [{Cu(bea)(Hbea)}4(μ4-pma)]n·2nH2O (3)-were generated by an aqueous medium self-assembly method from copper(II) nitrate, pyromellitic acid (H4pma), and different aminoalcohols [N,N-dimethylethanolamine (Hdmea), N-ethyldiethanolamine (H2edea), and N-benzylethanolamine (Hbea)]. Compounds 2 and 3 represent the first coordination polymers derived from H2edea and Hbea...
January 4, 2016: Inorganic Chemistry
Redouane Beniazza, Natalia Bayo, Florian Molton, Carole Duboc, Stéphane Massip, Nathan McClenaghan, Dominique Lastécouères, Jean-Marc Vincent
The search for copper catalysts able to perform effectively click reactions in water in the absence of sodium ascorbate is an active area of current research with strong potential for applications in bioconjugation. The water-soluble and photoreducible copper(II)-EDA (EDA = ethylenediamine) complex 1, which has two 4-benzoylbenzoates acting as both counterion and photosensitizer, has been synthesized and characterized by different techniques including single crystal X-ray diffraction. Highly efficient photoreduction was demonstrated when solutions of 1 in hydrogen atom donating solvents, such as THF or MeOH, were exposed to UVA radiation (350-400 nm) provided by a low pressure mercury lamp (type TLC = thin-layer chromatography, 365 nm), or by a 23 W fluorescent bulb, or by ambient/sunlight...
2015: Beilstein Journal of Organic Chemistry
Tia L Walker, Sam Mula, Wilhelm Malasi, James T Engle, Christopher J Ziegler, Art van der Est, Jody Modarelli, Michael J Taschner
To improve understanding of copper at the active site of Type 1 copper proteins, Cu(I) and Cu(II) complexes of 1,8-dithia-4,11-diazacyclotetradecane, shown in , have been successfully isolated and structurally characterized by X-ray crystallography. In these compounds, both Cu(I) and Cu(II) are centered in the plane of the macrocycle containing two sulphur and two nitrogen heteroatoms comprising the distorted tetrahedral/square planar coordination geometry. The UV/VIS spectra, electrochemistry and EPR properties have been obtained for the Cu(II) complex 2...
December 14, 2015: Dalton Transactions: An International Journal of Inorganic Chemistry
Jefferson S Plegaria, Matteo Duca, Cédric Tard, Thomas J Friedlander, Aniruddha Deb, James E Penner-Hahn, Vincent L Pecoraro
Using de novo protein design, we incorporated a copper metal binding site within the three-helix bundle α3D (Walsh et al. Proc. Natl. Acad. Sci. U.S.A. 1999, 96, 5486-5491) to assess whether a cupredoxin center within an α-helical domain could mimic the spectroscopic, structural, and redox features of native type-1 copper (CuT1) proteins. We aimed to determine whether a CuT1 center could be realized in a markedly different scaffold rather than the native β-barrel fold and whether the characteristic short Cu-S bond (2...
October 5, 2015: Inorganic Chemistry
Cristina N Butterfield, Lizhi Tao, Kelly N Chacón, Thomas G Spiro, Ninian J Blackburn, William H Casey, R David Britt, Bradley M Tebo
Multicopper oxidases (MCOs) catalyze the oxidation of a diverse group of metal ions and organic substrates by successive single-electron transfers to O2 via four bound Cu ions. MnxG, which catalyzes MnO2 mineralization by oxidizing both Mn(II) and Mn(III), is unique among multicopper oxidases in that it carries out two energetically distinct electron transfers and is tightly bound to accessory proteins. There are two of these, MnxE and MnxF, both approximately 12kDa. Although their sequences are similar to those found in the genomes of several Mn-oxidizing Bacillus species, they are dissimilar to those of proteins with known function...
December 2015: Biochimica et Biophysica Acta
Han-Woo Kim, So-Yeong Lee, Hyun Park, Sung-Jong Jeon
An open reading frame of the Thermus thermophilus HJ6 hypothetical laccase, which composed of 729 bases, was cloned and expressed as a fusion protein with six histidine residues in Escherichia coli SoluBL21™ cells. The resulting insoluble bodies were separated from cellular debris by centrifugation and solubilized with 6M guanidine HCl. The solubilized protein was refolded by a simple on-column refolding procedure using Ni-chelation affinity chromatography and then the refolded protein was purified by gel filtration chromatography...
October 2015: Protein Expression and Purification
Elena Pahonțu, Diana-Carolina Ilieș, Sergiu Shova, Codruța Paraschivescu, Mihaela Badea, Aurelian Gulea, Tudor Roșu
A novel Schiff base, ethyl 4-[(E)-(2-hydroxy-4-methoxyphenyl)methylene-amino]benzoate (HL), was prepared and structurally characterized on the basis of elemental analyses, (1)H NMR, (13)C NMR, UV-Vis and IR spectral data. Six new copper(II) complexes, [Cu(L)(NO3)(H2O)2] (1), [Cu(L)2] (2), [Cu(L)(OAc)] (3), [Cu2 (L)2Cl2(H2O)4] (4), [Cu(L)(ClO4)(H2O)] (5) and [Cu2(L2S)(ClO4)(H2O)]ClO4·H2O (6) have been synthesized. The characterization of the newly formed compounds was done by IR, UV-Vis, EPR, FAB mass spectroscopy, elemental and thermal analysis, magnetic susceptibility measurements and molar electric conductivity...
2015: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Rosana P Sartoris, Otaciro R Nascimento, Ricardo C Santana, Mireille Perec, Ricardo F Baggio, Rafael Calvo
A binuclear Cu(II) compound [Cu2(bpa)2(P2O7)(H2O)2]·2.5H2O, 1, (bpa = 2,2'-bipyridylamine), with pairs of Cu(II) ions bridged by one pyrophosphate tetra-anion, was synthesized and crystallized. Its triclinic structure was determined by single-crystal X-ray diffraction. Electron paramagnetic resonance (EPR) spectra of single crystal samples of 1 were recorded for a fixed orientation of the magnetic field (B0) as a function of temperature (T) between 4.7 and 293 K, and at T = 4.7, 50 and 293 K, as a function of the orientation of B0...
March 14, 2015: Dalton Transactions: An International Journal of Inorganic Chemistry
Nicole Kindermann, Eckhard Bill, Sebastian Dechert, Serhiy Demeshko, Edward J Reijerse, Franc Meyer
Copper enzymes play important roles in the binding and activation of dioxygen in biological systems. Key copper/dioxygen intermediates have been identified and studied in synthetic analogues of the metalloprotein active sites, including the μ-η(2):η(2)-peroxodicopper(II) motif relevant to type III dicopper proteins. Herein, we report the synthesis and characterization of a bioinspired dicopper system that forms a stable μ-η(1):η(1)-peroxo complex whose Cu-O-O-Cu torsion is constrained to around 90° by ligand design...
February 2, 2015: Angewandte Chemie
Hina Zafar, Abdul Kareem, Asif Sherwani, Owais Mohammad, Mohammad Azam Ansari, Haris M Khan, Tahir Ali Khan
A condensation reaction between 1,2-diphenylethane-1,2-dione dihydrazone (DPEDDH) and dimethyl or diethyloxalate in methanol resulted in a novel Schiff base octaazamacrocyclic ligand, (L): (6,7,14,15-tetraoxa-2,3,10,11-tetraphenyl-1,4,5,8,9,12,13,16-octaazacyclohexadecane-1,3,9,11-tetraene). Subsequently metal complexes of the type [MLX2] and [CuL]X2; (M=Mn(II), Co(II), Ni(II) and Zn(II); X=Cl or NO3) were synthesized by the reaction of the free macrocyclic ligand (L) with the corresponding metal salts in 1:1 molar ratio...
January 2015: Journal of Photochemistry and Photobiology. B, Biology
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