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Copper type ii EPR

H M Zhang, W B Xiao, Xiong Wan
Based on the studies of the electron paramagnetic resonance parameters for two types of the Cu2+ centers in Cd(HCOO)2 ·2H2 O by using the high-order perturbation formulas for a 3d9 ion in a rhombically elongated octahedron, local structure of the doped copper ion is determined. Research suggests that the impurity Cu2+ replaces the host Cd2+ and undergoes the local rhombic elongation distortion, characterized by the axial elongation ratios of 4.1%, and 3.8% along the z-axis and the planar bond length variation ratios of 3...
May 2018: Magnetic Resonance in Chemistry: MRC
Xuan Zhang, Nicolaas A Vermeulen, Zhiyuan Huang, Yuexing Cui, Jian Liu, Matthew D Krzyaniak, Zhanyong Li, Hyunho Noh, Michael R Wasielewski, Massimiliano Delferro, Omar K Farha
Two new UiO-68 type of Zr-MOFs featuring redox non-innocent catechol-based linkers of different redox activities have been synthesized through a de novo mixed-linker strategy. Metalation of the MOFs with Cu(II) precursors triggers the reduction of Cu(II) by the phenyl-catechol groups to Cu(I) with the concomitant formation of semiquinone radicals as evidenced by EPR and XPS characterization. The MOF-supported catalysts are selective toward the allylic oxidation of cyclohexene and it is found that the presence of in situ-generated Cu(I) species exhibits enhanced catalytic activity as compared to a similar MOF with Cu(II) metalated naphthalenyl-dihydroxy groups...
January 10, 2018: ACS Applied Materials & Interfaces
Selvaraj Vimalraj, Subramaniyam Rajalakshmi, Desingh Raj Preeth, Sivasubramanian Vinoth Kumar, Thirumalai Deepak, Venkatraman Gopinath, Kadarkarai Murugan, Suvro Chatterjee
Copper(II) complex of quercetin Cu+Q, mixed ligand complexes, quercetin-Cu(II)-phenanthroline [Cu+Q(PHt)] and quercetin-Cu(II)-neocuproine [Cu+Q(Neo)] have been synthesized and characterized. From the FT-IR spectroscopic studies, it was evident that C-ring of quercetin is involved in the metal chelation in all the three copper complexes. C-ring chelation was further proven by UV-Visible spectra and the presence of Cu(II) from EPR spectroscopic investigations. These complexes were found to have osteogenic and angiogenic properties, observed through in vitro osteoblast differentiation and chick embryo angiogenesis assay...
February 1, 2018: Materials Science & Engineering. C, Materials for Biological Applications
Sethuraman Muthuramalingam, Themmila Khamrang, Marappan Velusamy, Ramasamy Mayilmurugan
New copper(ii) complexes, [Cu(L1)2 (H2 O)](ClO4 )2 , 1 [L1 = 2-pyridin-2-yl-quinoline], [Cu(L2)2 (H2 O)](ClO4 )2 , 2 [L2 = 2-pyridin-2-yl-quinoxaline], [Cu(L3)2 (H2 O)](ClO4 )2 , 3 [L3 = 6,7-dimethyl-2-pyridin-2-yl-quinoxaline], [Cu(L4)2 (H2 O)](ClO4 )2 , 4 [L4 = 4-phenyl-2-pyridin-2-yl-quinoline] and [Cu(L5)2 (H2 O)](ClO4 )2 , 5 [L5 = 4-phenyl-2-pyridin-2-yl-quinazoline], were synthesized and characterized as catalysts for selective fixation of atmospheric CO2 . The molecular structure of 2 was determined by single-crystal X-ray studies and shown to have an unusual trigonal bipyramid geometry (τ, 0...
November 28, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
S K Hoffmann, J Goslar, R Bregier-Jarzebowska, A Gasowska, A Zalewska, L Lomozik
The mode of interaction and thermodynamic stability of complexes formed in binary and ternary Cu(II)/ATP/triamines systems were studied using potentiometric and spectroscopic (NMR, EPR, UV-Vis) methods. It was found that in binary metal-free systems ATP/Hx PA species are formed (PA: Spd=spermidine or 3,3-tri=1,7-diamino-4-azaheptane) where the phosphate groups from nucleotides are preferred negative centers and protonated amine groups of amines are positive centers of reaction. In the ternary systems Cu/ATP/Hx (PA) as well as Cu/(ATP)(PA) species are formed...
December 2017: Journal of Inorganic Biochemistry
Eszter N Tóth, Nóra V May, Antal Rockenbauer, Gábor Peintler, Béla Gyurcsik
The investigation of the linkage isomers of biologically essential and kinetically labile metal complexes in aqueous solutions poses a challenge, as these microspecies cannot be separately studied. Therefore, derivatives are commonly used to initially determine the stability or spectral characteristics of at least one of the isomers. Here we directly detect the isomers, describe the metal ion coordination sphere, speciation and thermodynamic parameters by a synergistic application of temperature dependent EPR and CD spectroscopic measurements in copper(ii)-dipeptide systems including His-Gly and His-Ala ligands...
June 27, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Lizhi Tao, Troy A Stich, Shu-Hao Liou, Alexandra V Soldatova, David A Delgadillo, Christine A Romano, Thomas G Spiro, David B Goodin, Bradley M Tebo, William H Casey, R David Britt
Manganese-oxide minerals (MnOx) are widely distributed over the Earth's surface, and their geochemical cycling is globally important. A multicopper oxidase (MCO) MnxG protein from marine Bacillus bacteria plays an essential role in producing MnOx minerals by oxidizing Mn(2+)(aq) at rates that are 3 to 5 orders of magnitude faster than abiotic rates. The MnxG protein is isolated as part of a multiprotein complex denoted as "Mnx" that includes accessory protein subunits MnxE and MnxF, with an estimated stoichiometry of MnxE3F3G and corresponding molecular weight of ≈211 kDa...
June 22, 2017: Journal of the American Chemical Society
Marie Ramirez Cohen, Netanel Mendelman, Marina Radoul, Tiffany D Wilson, Masha G Savelieff, Herbert Zimmermann, Ilia Kaminker, Akiva Feintuch, Yi Lu, Daniella Goldfarb
The electron transfer mediating properties of type I copper proteins stem from the intricate ligand coordination sphere of the Cu ion in their active site. These redox properties are in part due to unusual cysteine thiol coordination, which forms a highly covalent copper-sulfur (Cu-S) bond. The structure and electronic properties of type I copper have been the subject of many experimental and theoretical studies. The measurement of spin delocalization of the Cu(II) unpaired electron to neighboring ligands provides an elegant experimental way to probe the fine details of the electronic structure of type I copper...
June 5, 2017: Inorganic Chemistry
Prithwish Mahapatra, Soumavo Ghosh, Sanjib Giri, Vinayak Rane, Ramakant Kadam, Michael G B Drew, Ashutosh Ghosh
A new Cu(II) complex of an asymmetrically dicondensed Schiff base (H2 L = N-(2-hydroxyacetophenylidene)-N'-salicylidene-1,3-propanediamine) derived from 1,3-propanediamine, salicylaldehyde, and o-hydroxyacetophenone has been synthesized. Using this complex, [CuL] (1), as a metalloligand, two new trinuclear Cu-Mn complexes, [(CuL)2 Mn(N3 )(H2 O)](ClO4 )·H2 O (2) and [(CuL)2 Mn(NCS)2 ] (3), have been prepared. Single-crystal structural analyses reveal that complexes 2 and 3 both have the same bent trinuclear {(CuL)2 Mn}2+ structural unit in which two terminal bidentate square-planar (CuL) units are chelated to the central octahedral Mn(II) ion...
May 1, 2017: Inorganic Chemistry
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, (Bu4 N+ )2 [CuII (F8 Pc)4- ]2- ·2C6 H4 Cl2 (1) and (PPN+ )3 [CuF16 Pc]3 3- ·2C6 H5 CN (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 [CuII (F8 Pc)4- ]2- dianions are formed without reduction of CuII ...
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 ·2H2 O 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...
November 28, 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)2 H2 O] (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
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