Search results for "COPPER"
showing 10 items of 3029 documents
Synthesis, structure and properties of a novel self-assembled tetranuclear copper(II) complex derived from carboxylate-based multidentate ligand
2020
Abstract A novel tetranuclear copper(II) complex, [Cu(H2O)5][Cu4(cpdp)2(adip)]ClBr∙2CH3OH·8H2O (1) of carboxylate-based symmetrical multidentate ligand, H3cpdp [H3cpdp = N,N'-Bis[2-carboxybenzomethyl]-N,N'-Bis[2-pyridylmethyl]-1,3-diaminopropan-2-ol; adip = adipate], has been synthesized and fully characterized. Complex 1 has been synthesized by carrying out reaction of ligand H3cpdp with stoichiometric amounts of CuCl2·2H2O/Na2(CH2CH2COO)2 in methanol-water in the presence of NaOH at room temperature. The solid state structure of 1 consists of a [Cu4(µ4-adip)] core unit which is held together by two multidentate bridging ligands, cpdp3−. In fact, complex 1 can be viewed as a “dimer-of-dime…
Structure and performance properties of environmentally-friendly biocomposites based on poly(ɛ-caprolactone) modified with copper slag and shale dril…
2018
The potential application of two types of industrial wastes, drill cuttings (DC) and copper slag (CS), as silica-rich modifiers of poly(ɛ-caprolactone) (PCL) was investigated. Chemical structure and physical properties of DC and CS fillers were characterized using X-ray diffractometer, X-ray fluorescence spectroscopy, particle size and density measurements. PCL/DC and PCL/CS composites with a variable content of filler (5 to 50 parts by weight) were prepared by melt compounding in an internal mixer. It was observed that lower particle size of DC filler enhanced processing of biocomposites comparing to CS filler. Smaller particles of DC filler and thus the higher specific surface area, enabl…
Analysis of the oxidation process and mechanical evolution in nanosized copper spinel ferrites. Role of stresses on the coercivity
1997
Isothermal oxidations of the iron(II) and copper(I) cations in nanosized copper spinel ferrites which were oxidized in cation-deficient spinels have been studied by thermogravimetric analysis. The low temperature kinetics of oxidation of each oxidizable cation has been explained on the basis of a diffusion-induced stress effect, these stresses being generated in the ferrite particles by the chemical gradient induced during the oxidation process where the cations at the surface are more oxidized than those in the bulk. A reaction mechanism coupling the chemical and the mechanical effects has been proposed. When the Cu-ferrites contain some Co-cations, it has also been revealed that the stres…
Structural basis and effect of copper(II) complexes with 4-oxo-thiazolidine ligands on DNA binding and nuclease activity
2020
Abstract Seven novel Copper(II) complexes, namely [Cu(Am4DHotaz)(H2O)2](ClO4) (1), [Cu(Am4DHotaz)(NO3)(MeOH)]·H2O (2), [Cu(Am4Motaz)2(H2O)](ClO4)2·0.83H2O (3), [Cu(Am4Motaz)2(NO3)]NO3·MeOH (4), [Cu(Am4Eotaz)2(NO3)]3(NO3)3·2H2O (5), [Cu(Am4Eotaz)2(ClO4)](ClO4) (6) and [Cu(Am4Eotaz)(ClO4)(H2O)](ClO4) (6a) (HAm4DHotaz = N′-(4-oxothiazolidin-2-ylidene)pyridine-2-carbohydrazonamide, Am4Motaz = N′-(3-methyl-4-oxothiazolidin-2-ylidene)pyridine-2-carbohydrazonamide and Am4Eotaz = N′-(3-ethyl-4-oxothiazolidin-2-ylidene)pyridine-2-carbohydrazonamide), have been successfully synthesized and characterized by several physicochemical techniques and, for 1–6 complexes, single crystal X-ray diffraction. Ha…
Supramolecular diversity and magnetic properties of novel heterometallic Cu(II)/Cr(III) complexes prepared from copper powder, Reineckes salt and eth…
2009
Abstract Three novel heterometallic complexes [Cu(en) 2 Cr(NCS) 4 (NH 3 ) 2 ][Cr(NCS) 4 (NH 3 ) 2 ] · 6dmf ( 1 ), [Cu(en) 2 Cr(NCS) 4 (NH 3 ) 2 ](OAc) ( 2 ) and [{Cu(en) 2 } 3 {Cr(NCS) 4 (NH 3 ) 2 } 2 (NCS) 2 ](NCS) 2 ( 3 ) have been synthesized in a one-pot reaction from copper powder, Reineckes salt, NH 4 X [X − = OAc − ( 2 ), NCS − ( 3 )] in a dmf ( 1 ) or CH 3 CN ( 2 , 3 ) solution of ethylenediamine (en). X-ray studies showed that 1 and 2 consist of cationic polymeric chains, formed by Cu ( en ) 2 2 + and Cr ( NCS ) 4 ( NH 3 ) 2 - building blocks that bridged through thiocyanate anions. In both complexes, distinct hydrogen bonds are present and serve to increase the dimensionality of …
Synthesis of the first heterometalic star-shaped oxido-bridged MnCu3 complex and its conversion into trinuclear species modulated by pseudohalides (N…
2011
A tetra-nuclear, star-shaped hetero-metallic copper(II)-manganese(II) complex, [{CuL(H(2)O)}(2)(CuL)Mn](ClO(4))(2) (1) has been synthesized by reacting the "complex as ligand" [CuL] with Mn(ClO(4))(2) where H(2)L is the tetradentate di-Schiff base derived from 1,3-propanediamine and 2-hydroxyacetophenone. Upon treatment with the polyatomic anions azide, cyanate, or thiocyanate in methanol medium, complex 1 transforms into the corresponding trinuclear species [(CuL)(2)Mn(N(3))(2)] (2), [(CuL)(2)Mn(NCO)(2)] (3) and [(CuL)(2)Mn(NCS)(2)] (4). All four complexes have been structurally and magnetically characterized. In complex 1 the central Mn(II) ion is encapsulated by three terminal [CuL] unit…
Syntheses, crystal structures and magnetic properties of copper(II) polynuclear and dinuclear compounds with 2,3-bis(2-pyridyl)pyrazine (dpp) and pse…
2001
Abstract The preparation, crystal structures and magnetic properties of four heteroleptic copper(II) complexes with 2,3-bis(2-pyridyl)pyrazine (dpp) and azide, cyanate or thiocyanate as ligands are reported, [Cu(dpp)(N3)2]n (1), [Cu(dpp)(NCO)2]n (2), [Cu(dpp)(NCS)2]2 (3) and [Cu(H2O)(dpp)(NCS)2]2·2H2O (4). Compounds 1 and 2 are isomorphous, triclinic, space group P1, and consist of mononuclear building blocks featuring copper atoms with close to square planar coordination geometries. The mononuclear units are, however, associated into chains through weak axial Cu–N bonds formed by end-on asymmetrically bridging azido/cyanato groups and by pyridyl nitrogen atoms. Taking these contacts into a…
Unique copper ion catalyzed hydrolytic cleavage of C–N(2) bond of thiosemicarbazide
2006
Abstract For the first time, stable but coordinatively unsaturated Cu(II) complexes [Cu(2,2′-bpy)X2] · xH2O (X = ClO4, NO3, CH3COO and 2,2′-bpy = 2,2′-bipyridyl) have been found to promote the hydrolysis of C–N(2) bond of thiosemicarbazide (tsc) at 25 °C and at neutral pH yielding monomeric [Cu(2,2′-bpy)(NCS)2]. Direct reaction between [Cu(2,2′-bpy)2]Cl2 · 6H2O, KSCN and CuCl2 results in polymeric [Cu(2,2′-bpy)(NCS)2]n [1] [Inorg. Chim. Acta. 286 (1999) 108]. Similarly tsc is cleaved by Cu(I) complex [Cu(ϕ3P)2(CH3CN)2]ClO4 [ϕ3P = triphenylphosphine] which itself is converted into dimeric [Cu(ϕ3P)2(NCS)]2.
Pseudohalide derivatives of manganese(II) and copper(II) complexes with mepirizole, a biologically active pyrimidyl-pyrazole ligand
1989
Abstract The synthesis and characterization of thiocyanate and azide derivatives of mepirizole(4-methoxy-2-(5-methoxy-3-methyl-pyrazol-1-yl)-6-methylpyrimidine, hereinafter L) with manganese(II) and copper(II) is reported. The compounds were characterized by IR, electronic and EPR spectra and analytical data. Spectroscopic results suggest the existence of dimeric neutral entities [L2Cu2(μ-X)2(X)2] (X = NCS or N3) with unsymmetrical end-to-end bridges and five-coordination geometry around the copper(II) ion. Magnetic susceptibility data show that in the azide derivative the copper atoms are antiferromagnetically coupled (J = −18 cm−1), but no magnetic exchange interaction could be detected i…
Spectral and structural insights of copper reduction pathways in the system of CuX2-R2S (X=Cl, Br; R=allyl, n-propyl)
2021
Abstract We have explored the behaviour of Cu(II)/Cu(I) redox couple in the system CuX2-R2S, X = Cl, Br; R = allyl, n-propyl, under anhydrous and anaerobic conditions, thus simulating the reduction half cycle in the copper catalyzed oxidation of thioethers. In doing so, the Cl−Br substitution was critical for tuning the reduction potentials, while the replacement of propyl group by allyl group supported the trapping of oxidation by-product, halogen molecules. It was therefore possible to use the spectrophotometric titration, thereby providing information on the distribution of complex species in acetonitrile solution. The study showed that the trinuclear mixed−valence copper (I-II-II) aggre…