Structural Characterization Of Cu Research Articles

Novel azo- and bisazo-5-pyrazolone dyes and their application as a colorimetric chemosensor for naked eye recognition of Cu2+

In this study, novel azo- and bisazo-5-pyrazolones (1/2a, b, and 1/2c, d, respectively) were synthesized. The structures of the new compounds were characterized using FTIR, UV–Vis., 1H NMR, 13C NMR-APT, and HRMS spectroscopic methods. 1H-NMR study revealed that the compounds are in hydrazone- form in solution. Among fourteen metal nitrate salts, the azo-5-pyrazolones showed a colorimetric response only to the Cu2+ ion, whereas the new bisazo-5-pyrazolones did not cause a specific color change to only one cation. The produced ligand changed from orangey-yellow to very light yellow, making it possible to identify Cu2+ without the need for spectroscopic equipment. Compound 1b [4-((2,4-dimethylphenyl)diazenyl)-2-(naphthalene-1-yl)-5-phenyl-2,4-dihydro-3H-pyrazole-3-one)] was taken as a representative example of the new azo-5-pyrazolones for the chemosensor research. The Cu(1b)2 complex was also synthesized and characterized. The binding ratio between the 1b sensor and Cu2+ was found to be 2:1 (ligand:metal) from the structural characterization of Cu(1b)2 and using Job's plot method. The pH study showed that even if the pH changes, the Cu2+ ion can still bind to the 1b receptor. In the reversibility experiment, when EDTA was added to the (1b+Cu2+) solution, the spectrum returned to the 1b spectrum. The interference study showed the selectivity of 1b with Cu2+ even in the presence of other cations. A study of the detection limit (LOD) revealed considerable sensitivity towards Cu2+metal cation using absorption titration method and LOD value was found to be 4.31 μM. The association constant (Ka) of (1b+Cu2+) was determined to be 0.79×105M−1 using the Benesi-Hildebrand plot.

Structural Characterization of Cu(I)/Zn(II)-metallothionein-3 by Ion Mobility Mass Spectrometry and Top-Down Mass Spectrometry.

Mammalian zinc metallothionein-3 (Zn7MT3) plays an important role in protecting against copper toxicity by scavenging free Cu(II) ions or removing Cu(II) bound to β-amyloid and α-synuclein. While previous studies reported that Zn7MT3 reacts with Cu(II) ions to form Cu(I)4Zn(II)4MT3ox containing two disulfides (ox), the precise localization of the metal ions and disulfides remained unclear. Here, we undertook comprehensive structural characterization of the metal-protein complexes formed by the reaction between Zn7MT3 and Cu(II) ions using native ion mobility mass spectrometry (IM-MS). The complex formation mechanism was found to involve the disassembly of Zn3S9 and Zn4S11 clusters from Zn7MT3 and reassembly into Cu(I)xZn(II)yMT3ox complexes rather than simply Zn(II)-to-Cu(I) exchange. At neutral pH, the β-domain was shown to be capable of binding up to six Cu(I) ions to form Cu(I)6Zn(II)4MT3ox, although the most predominant species was the Cu(I)4Zn(II)4MT3ox complex. Under acidic conditions, four Zn(II) ions dissociate, but the Cu(I)4-thiolate cluster remains stable, highlighting the MT3 role as a Cu(II) scavenger even at lower than the cytosolic pH. IM-derived collision cross sections (CCS) reveal that Cu(I)-to-Zn(II) swap in Zn7MT3 with concomitant disulfide formation induces structural compaction and a decrease in conformational heterogeneity. Collision-induced unfolding (CIU) experiments estimated that the native-like folded Cu(I)4Zn(II)4MT3ox conformation is more stable than Zn7MT3. Native top-down MS demonstrated that the Cu(I) ions are exclusively bound to the β-domain in the Cu(I)4Zn(II)4MT3ox complex as well as the two disulfides, serving as a steric constraint for the Cu(I)4-thiolate cluster. In conclusion, this study enhances our comprehension of the structure, stability, and dynamics of Cu(I)xZn(II)yMT3ox complexes.

Structural characterization of Cu–tpy–nucleotide ternary complexes

Structural characterization of Cu–tpy–nucleotide ternary complexes

The Palladium(II) Complex of Aβ4-16 as Suitable Model for Structural Studies of Biorelevant Copper(II) Complexes of N-Truncated Beta-Amyloids.

The A peptide is a major beta-amyloid species in the human brain, forming toxic aggregates related to Alzheimer’s Disease. It also strongly chelates Cu(II) at the N-terminal Phe-Arg-His ATCUN motif, as demonstrated in A and A model peptides. The resulting complex resists ROS generation and exchange processes and may help protect synapses from copper-related oxidative damage. Structural characterization of Cu(II)A complexes by NMR would help elucidate their biological function, but is precluded by Cu(II) paramagneticism. Instead we used an isostructural diamagnetic Pd(II)-A complex as a model. To avoid a kinetic trapping of Pd(II) in an inappropriate transient structure, we designed an appropriate pH-dependent synthetic procedure for ATCUN Pd(II)A, controlled by CD, fluorescence and ESI-MS. Its assignments and structure at pH 6.5 were obtained by TOCSY, NOESY, ROESY, H-C HSQC and H-N HSQC NMR experiments, for natural abundance C and N isotopes, aided by corresponding experiments for Pd(II)-Phe-Arg-His. The square-planar Pd(II)-ATCUN coordination was confirmed, with the rest of the peptide mostly unstructured. The diffusion rates of A, Pd(II)-A and their mixture determined using PGSE-NMR experiment suggested that the Pd(II) complex forms a supramolecular assembly with the apopeptide. These results confirm that Pd(II) substitution enables NMR studies of structural aspects of Cu(II)-A complexes.

Experimental and Theoretical Structural Characterization of Cu–Au Tripods for Photothermal Anticancer Therapy

Anisotropic metal nanostructures (e.g., Au–Ag, Au–Cu) are emerging for biomedical and catalytic applications in recent years. Herein, we report a modified synthesis of Cu–Au tripod nanocrystals thr...

Syntheses and structural characterization of Cu(II) and Mn(II) coordination polymers with the neutral flexible bidentate N-donor ligands

Four new coordination polymers of [Cu(μ-bip)2(N3)2·2H2O]n (1), [Cu(μ-bbd)2(μ4-N3)4]n (2), [Mn(μ-bip)2(NCS)2]n (3) and [Mn(μ-bip)2(N3)2]n (4) were prepared by using the neutral N-donor ligands 1,3-bis(imidazolyl)propane (bip) and 1,4-bis(3,5-dimethylpyrazolyl)butane (bbd), mono-anionic NCS− or N3− ligands and appropriate metal salts of Cu(II) and Mn(II) ions. The results of the X-ray measurements demonstrate that in the crystal structure of 1, 3 and 4 the metal ions adopts MN6 (M=Cu, Mn) an octahedral geometry while, in the structure of 2, the copper(II) ion forms CuN5 trigonal bipyramides. In the polymer 1, 3 and 4 the N3− or NCS− groups are terminally bonded to the metal center and each bip ligand with anti-gauche conformation acts as bridging ligand connecting two metal ions to form a one-dimensional zig-zag chain. Whereas in the polymer 2, the N3 groups adopt so called End-on mode of connection with metal center and the each bbd with anti-anti-anti conformation acts as bridging connecting two copper(II) ions to form a two-dimensional network with a hcb [point symbol (36)] topology. Compounds 1, 3 and 4 are isostructural with each other.

Structural and optical properties of CuSe2 nanocrystals formed in thin solid Cu–Se film

This paper describes the structural and optical properties of Cu–Se thin films. The surface morphology of thin films was investigated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Formation of Cu–Se thin films is concluded to proceed unevenly, in the form of islands which later grew into agglomerates. The structural characterization of Cu–Se thin film was investigated using X-ray diffraction pattern (XRD). The presence of two-phase system is observed. One is the solid solution of Cu in Se and the other is low-pressure modification of CuSe2. The Raman spectroscopy was used to identify and quantify the individual phases present in the Cu–Se films. Red shift and asymmetry of Raman mode characteristic for CuSe2 enable us to estimate nanocrystal dimension. In the analysis of the far-infrared reflection spectra, numerical model for calculating the reflectivity coefficient of layered system, which includes film with nanocrystalite inclusions (modeled by Maxwell-Garnett approximation) and substrate, has been applied.

Thermal and structural characterization of Cu–Al–Mn–X (Ti, Ni) shape memory alloys

In this study, the Cu–Al–Mn–X (X = Ni, Ti) shape memory alloys at the range of 10–12 at.% of aluminum and 4–5 at.% manganese were produced by arc melting. We have investigated the effects of the alloying elements on the transformation temperatures, and the structural and the magnetic properties of the quaternary Cu–Al–Mn–X (X = Ni, Ti) shape memory alloys. The evolution of the transformation temperatures was studied by differential scanning calorimetry with different heating and cooling rates. The characteristic transformation temperatures and the thermodynamic parameters were highly sensitive to variations in the aluminum and manganese content, and it was observed that the nickel addition into the Cu–Al–Mn system decreased the transformation temperature although Ti addition caused an increase in the transformation temperatures. The effect of the nickel and the titanium on the thermodynamic parameters such as enthalpy and entropy values was investigated. The structural changes of the samples were studied by X-ray diffraction measurements and by optical microscope observations at room temperature. It is evaluated that the element Ni has been completely soluble in the matrix, and the main phase of the Cu–Al–Mn–Ni sample is martensite, and due to the low solubility of the Ti, the Cu–Al–Mn–Ti sample has precipitates, and a martensite phase at room temperature. The magnetic properties of the Cu–Al–Mn, Cu–Al–Mn–Ni and Cu–Al–Mn–Ti samples were investigated, and the effect of the nickel and the titanium on the magnetic properties was studied.

Structural characterization of Cu doped zinc ferri-chromites prepared by novel gel combustion route

The present study is investigated for Cu doped series of Zn1−x Cu x FeCrO4 (0.0 ≤ x ≤ 1.0) system prepared by sol–gel auto-combustion method. The as-claimed novelty of this route is in situ oxidizing environment of nitrate ions in gel increases rate of oxidation by lowering the decomposition temperature of component. The completion of solid state reaction was checked by thermogravimetric analysis while crystalline phase evolution was assessed by X-ray diffraction. All the compounds exhibit cubic spinel symmetry and lattice constant shows nonlinear behavior with copper content. A morphology of the grains formed was found by scanning electron microscope while element compositions by elemental dispersive X-ray spectroscopy. Infra-red spectral studies showed two fundamental bands correspond to the intrinsic vibrations of tetrahedral and octahedral complex. The results indicate that system transfers from normal to inverse spinel.

Ultraviolet–Visible Spectroscopy and Temperature-Programmed Techniques as Tools for Structural Characterization of Cu in CuMgAlOxMixed Metal Oxides

Ultraviolet–visible (UV–vis) spectroscopy was used in combination with temperature-programmed reduction (TPR) methods to provide information about the Cu structure in CuMgAlOx mixed oxides. UV–vis ...

Structural Characterization of Cu- 13.58%Al- 3.94%Ni (wt. %) shape memory alloy elaborated by fusion

This work concerns the structural characterization of Cu -13.58% Al- 3.94% Ni (wt. %) shape memory alloy elaborated by fusion using various techniques such as microscopy (OM and SEM), dilatometry and diffractometry (XRD). A particular attention is lent to the thermo elastic transformation may occur depending on the content of alloying and heat treatments' adopted. In this context, measurements of transformation temperatures were carried out. The microscopy is used for the characterization of alloy after different heat treatments adopted taking into account also the chemical composition. X-rays diffraction is used in order to access information on the different phases obtained and identify some types of martensite formed after quenching of alloy. The transformation temperatures are measured by the dilatometric analysis technique. This allows studying the structural evolution that occurs during heating and cooling of the alloy studied.

Structural Characterization of Cu[sub 2]O After the Evolution of H[sub 2] under Visible Light Irradiation

Photocatalysis of Cu 2 O powder was investigated to evaluate its ability for the stoichiometric decomposition of water into O 2 and H 2 . Although thus far it has been indicated that Cu 2 O can function as a photocatalyst for the overall water splitting, H 2 evolution was found to take place solely while there was no generation of O 2 . Moreover, the evolution rate of H 2 gradually decreased during prolonged irradiation, and consequently, the evolution of H 2 ceased. From the structural analyses of deactivated Cu 2 O, it appeared that the H 2 evolution originates in the self-oxidation of Cu 2 O to CuO.

Structural Characterization of Cu2+Functional Centers In ‘Lead-Free’ KNN Piezoelectrics

AbstractThe alkali niobate ferroelectrics ((K0.5Na0.5)NbO3, KNN) are promising candidates as alternatives for PZT (Pb(ZrxTi(1-x))O3) ceramics in piezoelectric technologies. In order to obtain dense compounds with desirable properties, CuO has been used as sintering aid. In this work, the defect chemistry of Cu2+doped KNN was investigated by means of electron paramagnetic resonance (EPR). Copper is found to be incorporated as acceptor-type centers on B-site in the perovskite structure and, due to charge compensation, two kinds of mutually compensating defect dipoles are formed.

Synthesis, spectroscopic, electrochemical and structural characterization of Cu(II) complexes with asymmetric NN′OS coordination spheres

A set of four Cu(II) complexes, [Cu(cdnapen)], [Cu(cdnappd)], [Cu(cdMenappd)] and [Cu(cdMeMeOsalpd)], derived from Schiff base ligands with an asymmetric NN′OS coordination sphere have been synthesized. The molecular and the crystal structures have been determined by X-ray diffractometry. The structural results confirm that the complexes are tetra coordinated. The copper (II) ion coordinates to two nitrogen atoms from the imine moiety of the ligand, a sulfur atom from the methyl dithiocarboxylate moiety and a phenolic oxygen atom. The complexes show an unusual tetrahedral distortion to the square-planar geometry around the metal centre in spite of the pseudomacrocyclic skeleton of the ligand. The complexes were further characterized by cyclic voltammetry and electron paramagnetic resonance spectroscopy. The degree of tetrahedral distortion of the complexes appears to be dependent on the number of carbon atoms of the aliphatic bridge and the nature of the coordinating atoms.

Preparation and crystal structural characterization of Cu(II) complex with piperidine-4-carboxylic acid

Copper(II) complex with piperidine-4-carboxylic acid (HPipe-4), Cu(HPipe-4)4(ClO4)2 (I) was prepared and characterized by IR, X-ray diffraction, and thermal analysis. The crystal is orthorhombic with space group Ccca, Z = 8, a =17.415(3) A, b =17.399(2) A, c = 21.426(3) A. The copper atom has a square surrounding and is coordinated by four carboxylato oxygen atoms in monodentate coordination mode. Full-matrix least-squares refinements gave a final R value of 0.0723 for 22169 reflections. The complex consists of two perpendicularly arranged molecules differing slightly in conformations and shows a three-dimensional polymeric structure formed by hydrogen bonds.

Structural characterization of Cu–Ti-based bulk metallic glass by advanced electron microscopy

The atomistic structure of a high-strength Cu42.5Ti41.5Ni7.5Zr2.5Hf5Si1 bulk metallic glass prepared by copper-mould casting has been characterized by transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). High-resolution TEM and high-angle annular dark-field observations revealed that crystalline nanoparticles with sizes less than 10 nm are embedded in an amorphous matrix. It was confirmed by energy-dispersive X-ray spectroscopy in combination with STEM that these nanoparticles possess higher copper content than the amorphous matrix. Nanobeam electron diffraction experiments indicated that their crystalline structure is basically face-centred cubic with ordered atomic arrangements.

Synthesis and structural characterization of Cu(I) and Ni(II) complexes that contain the bis[2-(diphenylphosphino)phenyl]ether ligand. Novel emission properties for the Cu(I) species.

The pseudotetrahedral complexes [Cu(NN)(DPEphos)]BF(4), where DPEphos = bis[2-(diphenylphosphino)phenyl]ether and NN = 1,10-phenanthroline (1), 2,9-dimethyl-1,10-phenanthroline (2), 2,9-di-n-butylphenanthroline (3), or two dimethylcyanamides (4), and NiCl(2)(DPEphos) (5) have been synthesized and structurally characterized by X-ray crystallography and their solution properties examined by use of a combination of cyclic voltammetry, NMR spectroscopy, and electronic absorption spectroscopy. Complexes 1-4 possess a reversible Cu(II)/Cu(I) couple at potentials upward of +1.2 V versus Ag/AgCl. Compounds 1-3 exhibit extraordinary photophysical properties. In room-temperature dichloromethane solution, the charge-transfer excited state of the dmp (dbp) derivative exhibits an emission quantum yield of 0.15 (0.16) and an excited-state lifetime of 14.3 mus (16.1 mus). Coordinating solvents quench the charge-transfer emission to a degree, but the photoexcited dmp complex 2 retains a lifetime of over a microsecond in acetone, methanol, and acetonitrile.

Synthesis, spectroscopic and structural characterization of Cu(II) derivatives of tris(pyrazol-1-yl)methanes

The reaction between CuX 2 (X=ClO 4, NO 3, Cl, Br and CH 3COO) and excess of tris(pyrazol-1-yl)methane ligands L (L=CH(pz) 3, CH(4-Mepz) 3, CH(3,5-Me 2pz) 3, CH(3,4,5-Me 3pz) 3 or CH(3-Mepz) 2(5-Mepz)) yields [CuX 2(L)], [{CuX 2} 3(L 2) 2] or [Cu(L 2)]X 2-type complexes. The ligand to metal ratio is dependent on the number and disposition of the Me substituents on the azole-type ligand and mainly on the nature of the counter-ion X. All complexes have been characterized in the solid state as well as in solution (IR and UV spectra, and conductivity determinations). The solid-state structures of [Cu{(3,5-Me 2pz) 3CH} 2](NO 3) 2, [Cu{(3,5-Me 2pz) 3CH} 2](ClO 4) 2·0.5H 2O, [Cu{(3,4,5-Me 3pz) 3CH} 2](NO 3) 2·H 2O, [Cu{(4-Mepz) 3CH} 2]Br 2·3H 2O have been determined by single crystal X-ray studies.

The influence of phenyl substituents on the redox potentials of sterically hindered tripodal ligand/copper complexes

Abstract The structural characterization of Cu(I) and Cu(II) complexes of tris(6-phenyl-2-pyridylmethyl)amine (tppa), a derivative of the known tris(2-pyridylmethyl)amine (tpa), was recently reported. The phenyl substituents in [Cu(tppa)AN](ClO4)2 stabilize the Cu(I) state by 300–480 mV relative to [Cu(tpa)AN](ClO4)2. Reported here is the synthesis of the compounds bis(2-pyridylmethyl)-6-phenyl-2-pyridylmethylamine (Phtpa) and bis(6-phenyl-2-pyridylmethyl)-2-pyridylmethylamine (Ph2tpa) and the synthesis and cyclic voltammetry studies of their Cu(II) perchlorate complexes. The mechanism by which the phenyl groups increase the redox potential was found to be solvent-dependent: in AN, the increase in potential is primarily due to reduced local dielectric; in IBN, DMF, and DMA, the steric interaction between coordinated solvent and the phenyl substituents becomes important. The redox behavior of these complexes is consistent with anticipated modes of binding of solvent molecules in the inner sphere of the Cu(II) complexes.

Synthesis and structural characterization of Cu I and Cu II-doped cordierites

The possible diffusion and localization of copper in hexagonal cordierite structure, either by Cu 1 insertion within the hexagonal channels or by Cu II substitution for Mg in octahedral sites have been studied. Limited amounts of Cu I (about 30% of theoretical values) can be inserted within the cordierite channels in statistically occupied 4e sites (0, 0, z with z = 0.06 and 0.10 respectively for Cu 0.5Mg 2Al 4.5Si 4.5O 18 and CuMg 2Al 5Si 4O 18). Cu 2+/Mg 2+ substitution is limited by the competitive formation of mullite and spinel phases.