Structure and magnetism of a Mn(III)-Mn(II)-Mn(II)-Mn(III) chain complex.

PubMed

Uhrecký, Róbert; Moncoľ, Ján; Koman, Marian; Titiš, Ján; Boča, Roman

2013-07-14

A novel tetranuclear manganese(II/III) complex with anions of pyridine-2,6-dicarboxylic acid (dipicolinic acid) has been synthesised and magneto-structurally characterised. The crystal structure of [Mn(II)2Mn(III)2(dipic)6(H2O)4]·2CH3OH·4H2O has been determined by single-crystal X-ray diffraction. The tetranuclear complex molecule [Mn(II)2Mn(III)2(dipic)6(H2O)4] is centrosymmetric and two manganese(II) and two manganese(III) atoms are bridged by four dipicolinate ligands. The complex molecules and uncoordinated water and methanol molecules are connected through hydrogen bonds and they form a 3D supramolecular hydrogen-bonding network.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xiao-Ling; Liu, Guang-Zhen, E-mail: gzliuly@126.com; Xin, Ling-Yun

Two topologically new Mn(II) coordination polymers, namely ([Mn{sub 2}(H{sub 4}ipca)(4,4′-bpy){sub 1.5}(CH{sub 3}CH{sub 2}OH){sub 0.5}(H{sub 2}O){sub 1.5}]·0.5CH{sub 3}CH{sub 2}OH·2.5H{sub 2}O){sub n} (1) and (Mn{sub 4}(H{sub 4}ipca){sub 2}(bze)(H{sub 2}O){sub 4}){sub n} (2) were prepared by the solvothermal reactions of Mn(II) acetate with 5-(2’,3’-dicarboxylphenoxy)isophthalic acid (H{sub 4}ipca) in the presence of different N-donor coligands (4,4′-bpy=4,4′-bipyridyl and bze=1, 4-bis(1-imidazoly)benzene). The single crystal X-ray diffractions reveal that two complexes display 3D metal-organic frameworks with binuclear and tetranuclear Mn(II) units, respectively. Complex 1 features a (3,4,6)-connected porous framework based on dinuclear Mn(II) unit with the (4.5{sup 2}){sub 2}(4{sup 2}.6{sup 8}.8{sup 3}.9{sup 2})(5{sup 2}.8.9{sup 2}.10) new topology,more » and complex 2 possesses a (3,8)-connected network based on tetranuclear Mn(II) unit with the (4{sup 2}.6){sub 2}(4{sup 4}.6{sup 14}.7{sup 7}.8{sup 2}.9) new topology. Magnetic analyses indicate that both two compounds show weak antiferromagnetic interactions within binuclear and tetranuclear Mn(II) units. - Graphical abstract: Two topologically new Mn(II) metal-organic frameworks with dinuclear and tetranuclear Mn(II) units respectively were assembled by using 5-(2′,3′-Dicarboxylphenoxy)isophthalic acid and N-donor ancillary coligands. Magnetic analysis revealed the existence of dominant antiferromagnetic interactions within the polynuclear Mn(II) units. - Highlights: • Mixed ligand strategy produces two topologically new MOFs with dinuclear and tetranuclear Mn(II) respectively. • Magnetic fitting gives weak antiferromagnetic interactions within the polynuclear Mn(II) units.« less

Crystal structures and vibrational spectroscopy of copper(I) thiourea complexes.

PubMed

Bowmaker, Graham A; Hanna, John V; Pakawatchai, Chaveng; Skelton, Brian W; Thanyasirikul, Yupa; White, Allan H

2009-01-05

Several synthetic strategies using copper(I) starting materials or copper(II) compounds and an in situ sulfite reductant have been used to systematically explore the chemistry of copper(I) complexes with thiourea and substituted thiourea ligands. This has resulted in the discovery of several new complexes and methods for the bulk synthesis of some previously reported complexes that had been prepared adventitiously in small quantity. The new complexes are (tu = thiourea, dmtu = N,N'-dimethylthiourea, etu = ethylenethiourea): [I(4)Cu(4)(tu)(6)].H(2)O, [Cu(4)(tu)(10)](NO(3)).tu.3H(2)O, [BrCu(dmtu)(3)], [ICu(dmtu)(3)](2), [BrCu(etu)(2)](2), [ICu(etu)(2)], [ICu(etu)(2)](3). [I(4)Cu(4)(tu)(6)].H(2)O has an adamantanoid structure, with four terminal iodide ligands and six doubly bridging tu ligands. In contrast to this, [Cu(4)(tu)(10)](NO(3)).tu.3H(2)O contains a tetranuclear cluster in which four of the tu ligands are terminal and the other six are doubly bridging. [BrCu(dmtu)(3)] is a mononuclear complex with tetrahedral coordination of copper by one bromide and three dmtu ligands, whereas [Cu(dmtu)(3)](2)I(2) has a centrosymmetric dimeric cation with two uncoordinated iodides, four terminal dmtu and two doubly bridging dmtu ligands, [(dmtu)(2)Cu(mu-S-dmtu)(2)Cu(dmtu)(2)]I(2). A reversal of this monomer to dimer trend from bromide to iodide is seen for the etu counterparts: [BrCu(etu)(2)](2) is a centrosymmetric dimer with two doubly bridging etu ligands, [(etu)BrCu(mu-S-etu)(2)CuBr(etu)], whereas [ICu(etu)(2)] is a trigonal planar monomer, although the novel [I(3)Cu(3)(etu)(6)] is also defined. Infrared and Raman spectra of the synthesized complexes were recorded and the metal-ligand vibrational frequencies have been assigned in many cases. The results confirm previously observed correlations between the vibrational frequencies and the corresponding bond lengths for complexes of the unsubstituted tu ligand. A mechanochemical/infrared method was used to synthesize [I(3)Cu(3)(etu)(6)] from CuI and etu, and to demonstrate the polymorphic transition from [ICu(etu)(2)] to [I(3)Cu(3)(etu)(6)].

Oxidation of a [Cu2S] complex by N2O and CO2: insights into a role of tetranuclearity in the CuZ site of nitrous oxide reductase.

PubMed

Bagherzadeh, Sharareh; Mankad, Neal P

2018-01-25

Oxidation of a [Cu 2 (μ-S)] complex by N 2 O or CO 2 generated a [Cu 2 (μ-SO 4 )] product. In the presence of a sulfur trap, a [Cu 2 (μ-O)] species also formed from N 2 O. A [Cu 2 (μ-CS 3 )] species derived from CS 2 modeled initial reaction intermediates. These observations indicate that one role of tetranuclearity in the Cu Z catalytic site of nitrous oxide reductase is to protect the crucial S 2- ligand from oxidation.

Synthesis, structural characterization, reactivity, and catalytic properties of copper(I) complexes with a series of tetradentate tripodal tris(pyrazolylmethyl)amine ligands.

PubMed

Haldón, Estela; Delgado-Rebollo, Manuela; Prieto, Auxiliadora; Alvarez, Eleuterio; Maya, Celia; Nicasio, M Carmen; Pérez, Pedro J

2014-04-21

Novel tris(pyrazolylmethyl)amine ligands Tpa(Me3), Tpa*(,Br), and Tpa(Br3) have been synthesized and structurally characterized. The coordination chemistries of these three new tetradentate tripodal ligands and the already known Tpa and Tpa* have been explored using different copper(I) salts as starting materials. Cationic copper(I) complexes [Tpa(x)Cu]PF6 (1-4) have been isolated from the reaction of [Cu(NCMe)4]PF6 and 1 equiv of the ligand. Complexes 2 (Tpa(x) = Tpa*) and 3 (Tpa(x) = Tpa(Me3)) have been characterized by X-ray studies. The former is a 1D helical coordination polymer, and the latter is a tetranuclear helicate. In both structures, the Tpa(x) ligand adopts a μ(2):κ(2):κ(1)-coordination mode. However, in solution, all of the four complexes form fluxional species. When CuI is used as the copper(I) source, neutral compounds 5-8 have been obtained. Complexes 6-8 exhibit a 1:1 metal-to-ligand ratio, whereas 5 presents 2:1 stoichiometry. Its solid-state structure has been determined by X-ray diffraction, revealing its 3D polymeric nature. The polymer is composed by the assembly of [Tpa2Cu4I4] units, in which Cu4I4 presents a step-stair structure. The Tpa ligands bridge the Cu4I4 clusters, adopting also a μ(2):κ(2):κ(1)-coordination mode. As observed for the cationic derivatives, the NMR spectra of 5-8 show the equivalence of the three pyrazolyl arms of the ligands in these complexes. The reactivities of cationic copper(I) derivatives 1-4 with PPh3 and CO have been explored. In all cases, 1:1 adducts [Tpa(x)CuL]PF6 [L = PPh3 (9-11), CO (12-15)] have been isolated. The crystal structure of [Tpa*Cu(PPh3)]PF6 (9) has been obtained, showing that the coordination geometry around copper(I) is trigonal-pyramidal with the apical position occupied by the tertiary amine N atom. The Tpa* ligand binds the Cu center to three of its four N atoms, with one pyrazolyl arm remaining uncoordinated. In solution, the carbonyl adducts 13-15 exist as a mixture of two isomers; the four- and five-coordinate species can be distinguished by means of their IR νCO stretching bands. Finally, the catalytic activities of complexes 1-4 have been demonstrated in carbene- and nitrene-transfer reactions.

Steric hindrances create a discrete linear Dy4 complex exhibiting SMM behaviour.

PubMed

Lin, Shuang-Yan; Zhao, Lang; Ke, Hongshan; Guo, Yun-Nan; Tang, Jinkui; Guo, Yang; Dou, Jianmin

2012-03-21

Two linear tetranuclear lanthanide complexes of general formula [Ln(4)(L)(2)(C(6)H(5)COO)(12)(MeOH)(4)], where HL = 2,6-bis((furan-2-ylmethylimino)methyl)-4-methylphenol, () and Ln(III) = Dy(III) (1) and Gd(III) (2), have been synthesized and characterized. The crystal structural analysis demonstrates that two Schiff-base ligands inhibit the growth of benzoate bridged 1D chains, leading to the isolation of discrete tetranuclear complexes due to their steric hindrances. Every Ln(III) ion is coordinated by eight donor atoms in a distorted bicapped trigonal-prismatic arrangement. Alternating current (ac) susceptibility measurements of complex 1 reveal a frequency- and temperature-dependent out-of-phase signal under zero dc field, typical of single-molecule magnet (SMM) behaviour with an anisotropic barrier Δ(eff) = 17.2 K.

An orthogonal ferromagnetically coupled tetracopper(II) 2 x 2 homoleptic grid supported by micro-O4 bridges and its DFT study.

PubMed

Roy, Somnath; Mandal, Tarak Nath; Barik, Anil Kumar; Pal, Sachindranath; Butcher, Ray J; El Fallah, Mohamed Salah; Tercero, Javier; Kar, Susanta Kumar

2007-03-28

A pyrazole based ditopic ligand (PzOAP), prepared by the reaction between 5-methylpyrazole-3-carbohydrazide and methyl ester of imino picolinic acid, reacts with Cu(NO3)2.6H2O to form a self-assembled, ferromagnetically coupled, alkoxide bridged tetranuclear homoleptic Cu(II) square grid-complex [Cu4(PzOAP)4(NO3)2] (NO3)2.4H2O (1) with a central Cu4[micro-O4] core, involving four ligand molecules. In the Cu4[micro-O4] core, out of four copper centers, two copper centers are penta-coordinated and the remaining two are hexa-coordinated. In each case of hexa-coordination, the sixth position is occupied by the nitrate ion. The complex 1 has been characterized structurally and magnetically. Although Cu-O-Cu bridge angles are too large (138-141 degrees) and Cu-Cu distances are short (4.043-4.131 A), suitable for propagation of expected antiferromagnetic exchange interactions within the grid, yet intramolecular ferromagnetic exchange (J = 5.38 cm(-1)) is present with S = 4/2 magnetic ground state. This ferromagnetic interaction is quite obvious from the bridging connections (d(x2-y2)) lying almost orthogonally between the metal centers. The exchange pathways parameters have been evaluated from density functional calculations.

Dinuclear copper(II) complexes with {Cu2(mu-hydroxo)bis(mu-carboxylato)}+ cores and their reactions with sugar phosphate esters: A substrate binding model of fructose-1,6-bisphosphatase.

PubMed

Kato, Merii; Tanase, Tomoaki; Mikuriya, Masahiro

2006-04-03

Reactions of CuX2.nH2O with the biscarboxylate ligand XDK (H2XDK = m-xylenediamine bis(Kemp's triacid imide)) in the presence of N-donor auxiliary ligands yielded a series of dicopper(II) complexes, [Cu2(mu-OH)(XDK)(L)2]X (L = N,N,N',N'-tetramethylethylenediamine (tetmen), X = NO3 (1a), Cl (1b); L = N,N,N'-trimethylethylenediamine (tmen), X = NO3 (2a), Cl (2b); L =2,2'-bipyridine (bpy), X = NO3 (3); L = 1,10-phenanthroline (phen), X = NO3 (4); L = 4,4'-dimethyl-2,2'-bipyridine (Me2bpy), X = NO3 (5); L = 4-methyl-1,10-phenanthroline (Mephen), X = NO3 (6)). Complexes 1-6 were characterized by X-ray crystallography (Cu...Cu = 3.1624(6)-3.2910(4) A), and the electrochemical and magnetic properties were also examined. Complexes 3 and 4 readily reacted with diphenyl phosphoric acid (HDPP) or bis(4-nitrophenyl) phosphoric acid (HBNPP) to give [Cu2(mu-phosphate)(XDK)(L)2]NO3 (L = bpy, phosphate = DPP (11); L = phen, phosphate = DPP (12), BNPP (13)), where the phsophate diester bridges the two copper ions in a mu-1,3-O,O' bidentate fashion (Cu...Cu = 4.268(3)-4.315(1) A). Complexes 4 and 6 with phen and Mephen have proven to be good precursors to accommodate a series of sugar monophosphate esters (Sugar-P) onto the biscarboxylate-bridged dicopper centers, yielding [Cu2(mu-Sugar-P)(XDK)(L)2] (Sugar-P = alpha-D-Glc-1-P (23a and b), D-Glc-6-P (24a and b), D-Man-6-P (25a), D-Fru-6-P (26a and b); L = phen (a), Mephen (b)) and [Cu2(mu-Gly-n-P)(XDK)(Mephen)2] (Gly-n-P = glycerol n-phosphate; n = 2 (21), 3 (22)), where Glc, Man, and Fru are glucose, mannose, and fructose, respectively. The structure of [Cu2(mu-MNPP)(XDK)(phen)2(CH3OH)] (20) was characterized as a reference compound (H2MNPP = 4-nitrophenyl phosphoric acid). Complexes 4 and 6 also reacted with d-fructose 1,6-bisphosphate (D-Fru-1,6-P2) to afford the tetranuclear copper(II) complexes formulated as [Cu4(mu-D-Fru-1,6-P2)(XDK)2(L)4] (L = phen (27a), Mephen (27b)). The detailed structure of 27a was determined by X-ray crystallography to involve two different tetranuclear complexes with alpha- and beta-anomers of D-Fru-1,6-P2, [Cu4(mu-alpha-D-Fru-1,6-P2)(XDK)2(phen)4] and [Cu4(mu-beta-D-Fru-1,6-P2)(XDK)2(phen)4], in which the D-Fru-1,6-P2 tetravalent anion bridges the two [Cu2(XDK)(phen)2]2+ units through the C1 and C6 phosphate groups in a mu-1,3-O,O' bidentate fashion (Cu...Cu = 4.042(2)-4.100(2) A). Notably, the structure with alpha-D-Fru-1,6-P2 demonstrated the presence of a strong hydrogen bond between the C2 hydroxyl group and the C1 phosphate oxygen atom, which may support the previously proposed catalytic mechanism in the active site of fructose-1,6-bisphosphatase.

Rhombus-shaped tetranuclear [Ln4] complexes [Ln = Dy(III) and Ho(III)]: synthesis, structure, and SMM behavior.

PubMed

Chandrasekhar, Vadapalli; Hossain, Sakiat; Das, Sourav; Biswas, Sourav; Sutter, Jean-Pascal

2013-06-03

The reaction of a new hexadentate Schiff base hydrazide ligand (LH3) with rare earth(III) chloride salts in the presence of triethylamine as the base afforded two planar tetranuclear neutral complexes: [{(LH)2Dy4}(μ2-O)4](H2O)8·2CH3OH·8H2O (1) and [{(LH)2Ho4}(μ2-O)4](H2O)8·6CH3OH·4H2O (2). These neutral complexes possess a structure in which all of the lanthanide ions and the donor atoms of the ligand remain in a perfect plane. Each doubly deprotonated ligand holds two Ln(III) ions in its two distinct chelating coordination pockets to form [LH(Ln)2](4+) units. Two such units are connected by four [μ2-O](2-) ligands to form a planar tetranuclear assembly with an Ln(III)4 core that possesses a rhombus-shaped structure. Detailed static and dynamic magnetic analysis of 1 and 2 revealed single-molecule magnet (SMM) behavior for complex 1. A peculiar feature of the χM" versus temperature curve is that two peaks that are frequency-dependent are revealed, indicating the occurrence of two relaxation processes that lead to two energy barriers (16.8 and 54.2 K) and time constants (τ0 = 1.4 × 10(-6) s, τ0 = 7.2 × 10(-7) s). This was related to the presence of two distinct geometrical sites for Dy(III) in complex 1.

Designed topology and site-selective metal composition in tetranuclear [MM'...M'M] linear complexes.

PubMed

Barrios, Leoní A; Aguilà, David; Roubeau, Olivier; Gamez, Patrick; Ribas-Ariño, Jordi; Teat, Simon J; Aromí, Guillem

2009-10-26

The ligand 1,3-bis[3-oxo-3-(2-hydroxyphenyl)propionyl]benzene (H(4)L), designed to align transition metals into tetranuclear linear molecules, reacts with M(II) salts (M=Ni, Co, Cu) to yield complexes with the expected [MMMM] topology. The novel complexes [Co(4)L(2)(py)(6)] (2; py=pyridine) and [Na(py)(2)][Cu(4)L(2)(py)(4)](ClO(4)) (3) have been crystallographically characterised. The metal sites in complexes 2 and 3, together with previously characterised [Ni(4)L(2)(py)(6)] (1), favour different coordination geometries. These have been exploited for the deliberate synthesis of the heterometallic complex [Cu(2)Ni(2)L(2)(py)(6)] (4). Complexes 1, 2, 3 and 4 exhibit antiferromagnetic interactions between pairs of metals within each cluster, leading to S=0 spin ground states, except for the latter cluster, which features two quasi-independent S=1/2 moieties within the molecule. Complex 4 gathers the structural and physical conditions, thus allowing it to be considered as prototype of a two-qbit quantum gate.

Tetra-μ3-iodido-tetra­kis­[(tri-n-butyl­phosphane-κP)copper(I)

PubMed Central

Klenk, Simon; Frey, Wolfgang; Bubrin, Martina; Laschat, Sabine

2014-01-01

The title complex, [Cu4I4(C12H27P)4], crystallizes with six mol­ecules in the unit cell and with three independent one-third mol­ecule fragments, completed by application of the relevant symmetry operators, in the asymmetric unit. The tetranuclear copper core shows a tetrahedral geometry (site symmetry 3..). The I atoms also form a tetra­hedron, with I⋯I distances of 4.471 (1) Å. Both tetra­hedra show an orientation similar to that of a pair of self-dual platonic bodies. The edges of the I-tetra­hedral structure are capped to the face centers of the Cu-tetra­hedron and vice versa. The Cuface⋯I distances are 2.18 Å (averaged) and the Iface⋯Cu distances are 0.78 Å (averaged). As a geometric consequence of these properties there are eight distorted trigonal–bipyramidal polyhedra evident, wherein each trigonal face builds up the equatorial site and the opposite Cu⋯I positions form the axial site. As expected, the n-butyl moieties are highly flexible, resulting in large elongations of their anisotropic displacement parameters. Some C atoms of the n-butyl groups were needed to fix alternative discrete disordered positions. PMID:24826086

Crystal structure of tetra-kis-(μ3-2-{[1,1-bis-(hy-droxy-meth-yl)-2-oxidoeth-yl]imino-meth-yl}phenolato)tetra-copper(II) ethanol monosolvate 2.5-hydrate.

PubMed

Wang, Weilun; Ran, Jingwen

2015-05-01

The title compound, [Cu4(C11H13NO4)4]·CH3CH2OH·2.5H2O, is an electronically neutral tetra-nuclear copper(II) complex with a cubane-like Cu4O4 core. The complete molecule has point group symmetry 2. The phenol hy-droxy group and one of the three alcohol hy-droxy groups of each 2-{[tris-(hy-droxy-meth-yl)meth-yl]imino-meth-yl}phenol ligand are depro-ton-ated, while the secondary amine and the other two hy-droxy groups remain unchanged. The Cu(II) atoms in the Cu4O4 core are connected by four μ3-O atoms from the deprotonated alcohol hy-droxy groups. Each of the penta-coordinated Cu(II) ions has an NO4 distorted square-pyramidal environment through coordination to the tridentate Schiff base ligands. The Cu-N/O bond lengths span the range 1.902 (4)-1.955 (4) Å, similar to values reported for related structures. There are O-H⋯O hydrogen-bond inter-actions between the complex molecules and the ethanol and water solvent molecules, leading to the formation of a three-dimensional network. The ethanol solvent molecule is disordered about a twofold rotation axis. One of the two independent water molecules is also located on this twofold rotation axis and shows half-occupancy.

Construction and optical properties of infinite Cd and finite Cu molecules stairs

NASA Astrophysics Data System (ADS)

Zhao, Qiang; Mao, Wutao; Shen, Zhi; Wang, Qinghong; Zhou, Qian

2017-02-01

Two coordination complexes, namely [(hpdq)(pta)Cd]n (1) and [(pptp)(pta)Cu2Cl] (2) have been synthesized by solvothermal method based on two polypyridyl ligands, 2,3,6,7,10,11-hexakis- (2-pyridyl)dipyrazino[2,3-f:2‧,3‧-h]quinoxaline) (hpdq), 4‧-(4- (3H-pyrrol-3-yl)phenyl)- 2,2‧:6‧,2″- terpyridine (pptp) and auxiliary ligand p-phthalic acid (pta), respectively. Single crystal x-ray diffraction analyses reveal that complexes 1 and 2 assembled based on distinct asymmetric unit comprising one and two respective polypyridyl ligands but one Cd(II) and two Cu(I)ions, respectively. Among them, The asymmetric units in 1 was extended to one dimensional chain via the link of auxiliary ligand pta, just like infinite layers of stairs that connected by cadmium ions as the node. While that in 2 to Zero dimensional tetranuclear structure via the link of auxiliary ligand pta, just like finite four layers of stairs that Copper ion as the node connection. Furthermore, solid fluorescence spectra properties of two complexes were also investigated, and the result shows the fluorescence intensity of complex 1 is stronger than that of the hpdq ligand, but the fluorescence intensity of complex 2 is weaker than that of the pptp ligand. CCDC number of 1and 2 are 1483301 and 1483302.

Hydrolysis and coordination behavior of ferrocenyl-phosphonodithiolate: Synthesis and structure of Cu 4[FcP(OCH 3)( μ-S)( μ3-S)] 4 [Fc = Fe( η5-C 5H 4)( η5-C 5H 5)

NASA Astrophysics Data System (ADS)

Liu, Shu-Lei; Wang, Xi-Ying; Duan, Taike; Leung, Wa-Hung; Zhang, Qian-Feng

2010-02-01

Treatment of the dimeric [FcP(S)( μ-S)] 2 [Fc = Fe( η5-C 5H 4)( η5-C 5H 5)] with the organic base Et 3N in methylene chloride solution resulted in the isolation of a multi-component compound [Et 3NH] 2[(FcPO 2S) 2CH 2][FcPS(OH) 2] 2·CH 2Cl 2 ( 1·CH 2Cl 2). The formation of the [(FcPO 2S) 2CH 2] 2- anion was due to the dechlorination of methylene chloride, it consists of two [FcPO 2S] 2- units bridging by a methylene group. Reaction of Na[FcP(OCH 3)S 2] with equal equivalent of [Cu(MeCN) 4][ClO 4] in methanol afforded a sole tetranuclear copper(I) complex Cu 4[FcP(OCH 3)( μ-S)( μ3-S)] 4 ( 2). The neutral complex 2 consists of a crystallographically centrosymmetric tetramer containing four CuS 3 arrays each of which has one μ-sulfur and two μ3-sulfur bridges.

Evolution of an adenine-copper cluster to a highly porous cuboidal framework: solution-phase ripening and gas-adsorption properties.

PubMed

Venkatesh, V; Pachfule, Pradip; Banerjee, Rahul; Verma, Sandeep

2014-09-15

The synthesis and directed evolution of a tetranuclear copper cluster, supported by 8-mercapto-N9-propyladenine ligand, to a highly porous three-dimensional cubic framework in the solid state is reported. The structure of this porous framework was unambiguously characterized by X-ray crystallography. The framework contains about 62 % solvent-accessible void; the presence of a free exocyclic amino group in the porous framework facilitates reversible adsorption of gas and solvent molecules. Oriented growth of framework in solution was also tracked by force and scanning electron microscopy studies, leading to identification of an intriguing ripening process, over a period of 30 days, which also revealed formation of cuboidal aggregates in solution. The elemental composition of these cuboidal aggregates was ascertained by EDAX analysis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis, characterization and single crystal structures of chiral Schiff base and its tetranuclear palladium complex with Pdsbnd Osbnd Pd bridging and Pdsbnd Pd bonds

NASA Astrophysics Data System (ADS)

Rajegowda, H. R.; Kumar, P. Raghavendra; Hosamani, Amar; Butcher, R. J.; Naveen, S.; Lokanath, N. K.

2018-03-01

A new chiral Schiff base ligand 2-{N-[(2S)-(1-hydroxy-3-phenylpropan-2-yl]ethanimidoyl} phenol ((S)sbnd H2L) was obtained by acid catalyzed condensation of (2S)-(-)-2-amino-3-phenyl-1-propanol with 2‧-hydroxyacetophenone. The palladium complex was prepared by treating a solution of (S)sbnd H2L in acetone with a solution of Na2PdCl4 in water in 1:1 M ratio. The new ligand and its complex were characterized by FT-IR, 1H, 13C{1H} NMR spectroscopy, polarimetry and elemental analysis and their molecular structures were determined by single crystal X-ray diffraction. Both the compounds crystallizes in monoclinic system in the space group P21. There exists an intra [Osbnd H ⋯N (1.62(5) Å)] and intermolecular [Osbnd H ⋯O (1.53(5) Å) and Csbnd H ⋯O (2.59 Å)] hydrogen bonding and secondary interactions in the crystal of (S)sbnd H2L. The structure of the palladium complex was found very interesting wherein the ligand coordinated to metal center as tridentate dianionic (O-, N, O-) fashion, (S)-L, resulting in a tetranuclear palladium cluster, [Pd4((S)-L)4]. In these supramolecular structures phenolate oxygen coordinated to Pd(II) ion as Pdsbnd O terminal bonds [1.934(12) - 1.977(11) Å] and the alkoxide oxygen coordinated as Pdsbnd Osbnd Pd bridging bonds [1.993(11) - 2.012(12) Å]. The Pdsbnd N bond lengths found were in the range of 1.949(13) to 1.919(12) Å. There exists two asymmetric tetranuclear complex molecules in its crystal lattice. There exists very strong metal-metal bond interaction, Pd(2)sbnd Pd(3) [3.0410(18) Å] and Pd(6)sbnd Pd(7) [3.0517(19) Å] respectively in the two asymmetric units.

A One-Pot Self-Assembly Reaction to Prepare a Supramolecular Palladium(II) Cyclometalated Complex: An Undergraduate Organometallic Laboratory Experiment

ERIC Educational Resources Information Center

Fernandez, Alberto; Lopez-Torres, Margarita; Fernandez, Jesus J.; Vazquez-Garcia, Digna; Vila, Jose M.

2012-01-01

A laboratory experiment for students in advanced inorganic chemistry is described. Students prepare palladium(II) cyclometalated complexes. A terdentate [C,N,O] Schiff base ligand is doubly deprotonated upon reaction with palladium(II) acetate in a self-assembly process to give a palladacycle with a characteristic tetranuclear structure. This…

Synthesis and structure of tetranuclear orthometallated Pd(II) complexes derived from bis-iminophosphoranes.

PubMed

Bielsa, Raquel; Navarro, Rafael; Soler, Tatiana; Urriolabeitia, Esteban P

2008-04-07

The reaction of Pd(OAc)2 with bis-iminophosphoranes Ph3P=NCH2CH2CH2N=PPh3 (1a), [C6H4(C(O)N=PPh3)2-1,3] (1b) and [C6H4(C(O)N=PPh3)2-1,2] (1c), gives the orthopalladated tetranuclear complexes [{Pd(mu-Cl){C6H4(PPh2=NCH2-kappa-C,N)-2}}2CH2]2 (2a) [{Pd(mu-OAc){C6H4(PPh2=NC(O)-kappa-C,N)-2}}2C6H4-1',3']2 (2b) and [{Pd(mu-OAc){C6H4(PPh2=NC(O)-kappa-C,N)-2}}2C6H4-1',2']2 (2c). The reaction takes place in CH2Cl2 for 1a, but must be performed in glacial acetic acid for 1b and 1c. The process implies in all cases the activation of a C-H bond on a Ph ring of the phosphonium group, with concomitant formation of endo complexes. This is the expected behaviour for 1a, but for 1b and 1c reverses the exo orientation observed in other ketostabilized iminophosphoranes. The influence of the solvent in the orientation of the reaction is discussed. The dinuclear acetylacetonate complexes [{Pd(acac-O,O'){C6H4(PPh2=NCH2-kappa-C,N)-2}}2CH2] (3a), [{Pd(acac-O,O'){C6H4(PPh2=NC(O)-kappa-C,N)-2}}2C6H4-1',3'] (3b) and [{Pd(acac-O,O'){C6H4(PPh2=NC(O)-kappa-C,N)-2}}2C6H4-1',2'] (3c) have been obtained from the halide-bridging tetranuclear derivatives. The X-ray crystal structure of [3c.4CHCl3] is also reported.

Crystal structure of tetra-kis-(μ3-2-{[1,1-bis-(hy-droxy-meth-yl)-2-oxidoeth-yl]imino-meth-yl}-6-meth-oxy-phenolato)tetra-kis-[aqua-copper(II)]: a redetermination at 200 K.

PubMed

Buvaylo, Elena A; Vassilyeva, Olga Yu; Skelton, Brian W

2015-10-01

The crystal structure of the tetra-nuclear title compound, [Cu4(C12H15NO5)4(H2O)4], has been previously reported by Back, Oliveira, Canabarro & Iglesias [Z. Anorg. Allg. Chem. (2015), 641, 941-947], based on room-temperature data. In the previously published structure, no standard uncertainties are recorded for the deprotonated hy-droxy-methyl group and water mol-ecule O atoms coordinating to the metal atom indicating that they were not refined; furthermore, the H atoms of some OH groups and water mol-ecules have not been positioned accurately. Since the current structure was determined at a lower temperature, all atoms, including the H atoms of these hy-droxy groups and the water mol-ecule, have been determined more accurately resulting in improved standard uncertainties in the bond lengths and angles. Diffraction data were collected at 200 K, rather than the more usual 100 K, due to apparent disordering at lower temperatures. In addition, it is now possible to report intra- and inter-molecular O-H⋯O inter-actions. In the title complex molecule, which has crystallographic -4 symmetry, the Cu(II) ions are coordinated by the tridentate Schiff base ligands and water mol-ecules, forming a tetra-nuclear Cu4O4 cubane-like core. The Cu(II) ion adopts a CuNO5 elongated octa-hedral environment. The coordination environment of Cu(II) at 200 K displays a small contraction of the Cu-N/O bonds, compared with the room-temperature structure. In the crystal lattice, the neutral clusters are linked by inter-molecular O-H⋯O hydrogen bonds into a one-dimensional hydrogen-bonding network propagating along the b axis.

Three's company: co-crystallization of a self-assembled S(4) metallacyclophane with two diastereomeric metallacycle intermediates.

PubMed

Lindquist, Nathan R; Carter, Timothy G; Cangelosi, Virginia M; Zakharov, Lev N; Johnson, Darren W

2010-05-28

Three discrete supramolecular self-assembled arsenic(iii) complexes including an unusual S(4)-symmetric tetranuclear [As(4)L(2)Cl(4)] metallacyclophane and two diastereomeric cis/trans-[As(2)LCl(2)] metallacycle intermediates co-crystallize within a single crystal lattice.

Rational Design of a Lanthanide-Based Complex Featuring Different Single-Molecule Magnets.

PubMed

Pointillart, F; Guizouarn, T; Lefeuvre, B; Golhen, S; Cador, O; Ouahab, L

2015-11-16

The rational synthesis of the 2-{1-methylpyridine-N-oxide-4,5-[4,5-bis(propylthio)tetrathiafulvalenyl]-1H-benzimidazol-2-yl}pyridine ligand (L) is described. It led to the tetranuclear complex [Dy4(tta)12(L)2] (Dy-Dy2-Dy) after coordination reaction with the precursor Dy(tta)3⋅2 H2O (tta(-) = 2-thenoyltrifluoroacetonate). The X-ray structure of Dy-Dy2-Dy can be described as two terminal mononuclear units bridged by a central antiferromagnetically coupled dinuclear complex. The terminal N2O6 and central O8 environments are described as distorted square antiprisms. The ac magnetism measurements revealed a strong out-of-phase signal of the magnetic susceptibility with two distinct sets of data. The high- and low-frequency components were attributed to the two terminal mononuclear single-molecule magnets (SMMs) and the central dinuclear SMM, respectively. A magnetic hysteresis loop was detected at very low temperature. From both structural and magnetic points of view, the tetranuclear SMM Dy-Dy2-Dy is a self-assembly of two known mononuclear SMMs bridged by a known dinuclear SMM. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and characterization of the tetranuclear iron(III) complex of a new asymmetric multidentate ligand. A structural model for purple acid phosphatases.

PubMed

Boudalis, Athanassios K; Aston, Robyn E; Smith, Sarah J; Mirams, Ruth E; Riley, Mark J; Schenk, Gerhard; Blackman, Allan G; Hanton, Lyall R; Gahan, Lawrence R

2007-11-28

The ligand, 2-((2-hydroxy-5-methyl-3-((pyridin-2-ylmethylamino)methyl)benzyl)(2-hydroxybenzyl)amino)acetic acid (H(3)HPBA), which contains a donor atom set that mimics that of the active site of purple acid phosphatase is described. Reaction of H(3)HPBA with iron(III) or iron(II) salts results in formation of the tetranuclear complex, [Fe(4)(HPBA)(2)(OAc)(2)(mu-O)(mu-OH)(OH(2))(2)]ClO(4) x 5H(2)O. X-Ray structural analysis reveals the cation consists of four iron(III) ions, two HPBA(3-) ligands, two bridging acetate ligands, a bridging oxide ion and a bridging hydroxide ion. Each binucleating HPBA(3-) ligand coordinates two structurally distinct hexacoordinate iron(III) ions. The two metal ions coordinated to a HPBA(3-) ligand are linked to the two iron(III) metal ions of a second, similar binuclear unit by intramolecular oxide and hydroxide bridging moieties to form a tetramer. The complex has been further characterised by elemental analysis, mass spectrometry, UV-vis and MCD spectroscopy, X-ray crystallography, magnetic susceptibility measurements and variable-temperature Mössbauer spectroscopy.

Electron transfer complex between nitrous oxide reductase and cytochrome c552 from Pseudomonas nautica: kinetic, nuclear magnetic resonance, and docking studies.

PubMed

Dell'acqua, Simone; Pauleta, Sofia R; Monzani, Enrico; Pereira, Alice S; Casella, Luigi; Moura, José J G; Moura, Isabel

2008-10-14

The multicopper enzyme nitrous oxide reductase (N 2OR) catalyzes the final step of denitrification, the two-electron reduction of N 2O to N 2. This enzyme is a functional homodimer containing two different multicopper sites: CuA and CuZ. CuA is a binuclear copper site that transfers electrons to the tetranuclear copper sulfide CuZ, the catalytic site. In this study, Pseudomonas nautica cytochrome c 552 was identified as the physiological electron donor. The kinetic data show differences when physiological and artificial electron donors are compared [cytochrome vs methylviologen (MV)]. In the presence of cytochrome c 552, the reaction rate is dependent on the ET reaction and independent of the N 2O concentration. With MV, electron donation is faster than substrate reduction. From the study of cytochrome c 552 concentration dependence, we estimate the following kinetic parameters: K m c 552 = 50.2 +/- 9.0 muM and V max c 552 = 1.8 +/- 0.6 units/mg. The N 2O concentration dependence indicates a K mN 2 O of 14.0 +/- 2.9 muM using MV as the electron donor. The pH effect on the kinetic parameters is different when MV or cytochrome c 552 is used as the electron donor (p K a = 6.6 or 8.3, respectively). The kinetic study also revealed the hydrophobic nature of the interaction, and direct electron transfer studies showed that CuA is the center that receives electrons from the physiological electron donor. The formation of the electron transfer complex was observed by (1)H NMR protein-protein titrations and was modeled with a molecular docking program (BiGGER). The proposed docked complexes corroborated the ET studies giving a large number of solutions in which cytochrome c 552 is placed near a hydrophobic patch located around the CuA center.

A neodymium(III)-ammonium complex involving oxalate and carbonate ligands: (NH4)2[Nd2(C2O4)3(CO3)(H2O)].H2O.

PubMed

Trombe, Jean-Christian; Galy, Jean; Enjalbert, Renée

2002-10-01

The title compound, diammonium aqua-mu-carbonato-tri-mu-oxalato-dineodymium(III) hydrate, (NH(4))(2)[Nd(2)(CO(3))(C(2)O(4))(3)(H(2)O)].H(2)O, involving the two ligands oxalate and carbonate, has been prepared hydrothermally as single crystals. The Nd atoms form a tetranuclear unit across the inversion centre at (1/2, 1/2, 1/2). Starting from this tetranuclear unit, the oxalate ligands serve to develop a three-dimensional network. The carbonate group acts as a bis-chelating ligand to two Nd atoms, and is monodentate to a third Nd atom. The oxalate groups are all bis-chelating. The two independent Nd atoms are ninefold coordinated and the coordination polyhedron of these atoms is a distorted monocapped antiprism.

Synthesis, Structure and Electrochemistry of Tetranuclear Oxygen-Centered Copper(II) Clusters with Acetylacetone and Benz-pyrazole Hydrolyzed Derivatives as Ligand.

PubMed

Vafazadeh, Rasoul; Willis, Anthony C

2016-01-01

Two copper(II) clusters Cu(4)OCl(6)(pyrazole)4, 1, and Cu(4)OBr(6)(Br-pyrazole)4, 2, have been synthesized by reacting acetylacetone and benzohydrazide (1:1 ratio) with CuX(2) (X = Cl for 1 and X= Br for 2) in methanol solutions. The structures of both clusters have been established by X-ray crystallography. The clusters contain four Cu, one O, six μ(2)-X atoms, and four pyrazole ligands. The pyrazoles was prepared in situ by the reaction of acetylacetone with benzohydrazide in methanol under reflux. In 2, the methine hydrogens of the pyrazole ligands have been replaced by bromine atoms. The four copper atoms encapsulate the central O atom in a tetrahedral arrangement. All copper atoms are five-coordinate and have similar coordination environments with slightly distorted trigonal bipyramidal geometry. The cyclic voltammogram of the clusters 1 and 2 show a one-electron quasi-reversible reduction wave in the region 0.485 to 0.731 V, and a one-electron quasi-reversible oxidation wave in the region 0.767 to 0.898 V. In 1, one irreversible oxidative response is observed on the positive of side of the voltammogram at 1.512 V and this can be assigned to Cu(II) to Cu(III) oxidation.

Formation of a cytochrome c-nitrous oxide reductase complex is obligatory for N2O reduction by Paracoccus pantotrophus.

PubMed

Rasmussen, Tim; Brittain, Thomas; Berks, Ben C; Watmough, Nicholas J; Thomson, Andrew J

2005-11-07

Nitrous oxide reductase (N2OR) catalyses the final step of bacterial denitrification, the two-electron reduction of nitrous oxide (N2O) to dinitrogen (N2). N2OR contains two metal centers; a binuclear copper center, CuA, that serves to receive electrons from soluble donors, and a tetranuclear copper-sulfide center, CuZ, at the active site. Stopped flow experiments at low ionic strengths reveal rapid electron transfer (kobs=150 s-1) between reduced horse heart (HH) cytochrome c and the CuA center in fully oxidized N2OR. When fully reduced N2OR was mixed with oxidized cytochrome c, a similar rate of electron transfer was recorded for the reverse reaction, followed by a much slower internal electron transfer from CuZ to CuA(kobs=0.1-0.4 s-1). The internal electron transfer process is likely to represent the rate-determining step in the catalytic cycle. Remarkably, in the absence of cytochrome c, fully reduced N2OR is inert towards its substrate, even though sufficient electrons are stored to initiate a single turnover. However, in the presence of reduced cytochrome c and N2O, a single turnover occurs after a lag-phase. We propose that a conformational change in N2OR is induced by its specific interaction with cytochrome c that in turn either permits electron transfer between CuA and CuZ or controls the rate of N2O decomposition at the active site.

Efficient enhancement of magnetic anisotropy by optimizing the ligand-field in a typically tetranuclear dysprosium cluster.

PubMed

Liu, Jiang; Chen, Yan-Cong; Jiang, Zhong-Xia; Liu, Jun-Liang; Jia, Jian-Hua; Wang, Long-Fei; Li, Quan-Wen; Tong, Ming-Liang

2015-05-07

The perturbation to the ligand field around the lanthanide ion may significantly contribute to the magnetic dynamics of single molecule magnets. This can be demonstrated by two typical Dy4 cluster-based single molecular magnets (SMMs), [Dy4X2(μ3-OH)2(μ-OH)2(2,2-bpt)4(H2O)4]X2·2H2O·4EtOH (X = Cl and Br for and , respectively), which were constructed by using 3,5-bis(pyridin-2-yl)-1,2,4-triazole (2,2-bptH) as the polynuclear-chelating ligand. Alternating-current (ac) magnetic susceptibility measurements show that the energy barriers in complexes and were immensely enhanced by comparing with our previous work due to the optimization of the ligand field around Dy(III) ions. Remarkably, their high thermal active barriers at 190 K () and 197 K () under a zero applied external dc magnetic field are also among the highest within the reported tetranuclear lanthanide-based SMMs.

Structure, magnetic properties, polarized neutron diffraction, and theoretical study of a copper(II) cubane.

PubMed

Aronica, Christophe; Chumakov, Yurii; Jeanneau, Erwann; Luneau, Dominique; Neugebauer, Petr; Barra, Anne-Laure; Gillon, Béatrice; Goujon, Antoine; Cousson, Alain; Tercero, Javier; Ruiz, Eliseo

2008-01-01

The paper reports the synthesis, X-ray and neutron diffraction crystal structures, magnetic properties, high field-high frequency EPR (HF-EPR), spin density and theoretical description of the tetranuclear CuII complex [Cu4L4] with cubane-like structure (LH2=1,1,1-trifluoro-7-hydroxy-4-methyl-5-aza-hept-3-en-2-one). The simulation of the magnetic behavior gives a predominant ferromagnetic interaction J1 (+30.5 cm(-1)) and a weak antiferromagnetic interaction J2 (-5.5 cm(-1)), which correspond to short and long Cu-Cu distances, respectively, as evidence from the crystal structure [see formulate in text]. It is in agreement with DFT calculations and with the saturation magnetization value of an S=2 ground spin state. HF-EPR measurements at low temperatures (5 to 30 K) provide evidence for a negative axial zero-field splitting parameter D (-0.25+/-0.01 cm(-1)) plus a small rhombic term E (0.025+/-0.001 cm(-1), E/D = 0.1). The experimental spin distribution from polarized neutron diffraction is mainly located in the basal plane of the CuII ion with a distortion of yz-type for one CuII ion. Delocalization on the ligand (L) is observed but to a smaller extent than expected from DFT calculations.

Employing linear tetranuclear [Zn4(COO)4(OH)2] clusters as building subunits to construct a new Zn(II) coordination polymer with tunable luminescent properties

NASA Astrophysics Data System (ADS)

Li, Wu-Wu; Zhang, Zun-Ting

2016-02-01

A new Zn(II) coordination polymer, [Zn2(btc) (biimpy) (OH)]n (1 H3btc = 1,3,5-benzenetricarboxylic acid, biimpy = 2,6-bis(1-imdazoly)pyridine) has been successfully synthesized and characterized by elemental analysis, powder single crystal X-ray diffraction analyses. Compound 1 features a 3D framework employing linear tetranuclear [Zn4(COO)4(OH)2] cluster as building subunits. Topological analysis reveals it represents a (3,10)-connected structural topology by viewing btc3-, linear tetranuclear clusters and biimpy as 3-connected nodes, 10-connected nodes, linear linkers, respectively. Moreover, the thermal stability and luminescent property of compound 1 have been well investigated.

Synthesis of Surface-Analogue Square-Planar Tetranuclear Nickel Hydride Clusters and Bonding to μ4-NR, -O and -BH Ligands.

PubMed

Shoshani, Manar M; Beck, Robert; Wang, Xiaoping; McLaughlin, Matthew J; Johnson, Samuel A

2018-03-05

Tetranuclear Ni complexes were synthesized with bonding to BH, NR, and O in atypical surface-like geometries. The previously reported electron-deficient cluster [( i Pr 3 P)Ni] 5 H 6 (1) reacts with N-methylmorpholine oxide to give [( i Pr 3 P)Ni] 4 H 4 (μ 4 -O) (2), which contains O coordinated in the center of a square-plane arrangement of Ni atoms. Reaction of 1 with benzonitrile gave the square-planar tetranuclear Ni cluster [( i Pr 3 P)Ni] 4 H 4 (μ 4 -NCH 2 Ph) (3), which contains an imido donor in a square-based-pyramidal geometry. This reaction also gives [( i Pr 3 P)Ni(N≡CPh)] 3 (4), with bridging benzonitrile ligands. Trimer 4 was independently synthesized from the reaction of Ni(COD) 2 , i Pr 3 P, and PhC≡N. The addition of dihydrogen to a 1:1 mixture of [( i Pr 3 P) 2 Ni] 2 (N 2 ) and ( i Pr 3 P) 2 NiCl 2 yielded [( i Pr 3 P)Ni] 4 (μ 3 -H) 4 (μ 2 -Cl) 2 (5), with a tetrahedral Ni core, in contrast to the square-planar geometries of 2 and 3. The solid-state structure of 5 was determined using both X-ray and neutron diffraction. Reaction of 5 with LiBH 4 gave [( i Pr 3 P)Ni] 4 H 4 (μ 4 -BH) 2 ] (6) via loss of LiCl and H 2 .

3D coordination polymers with nitrilotriacetic and 4,4'-bipyridyl mixed ligands: structural variation based on dinuclear or tetranuclear subunits assisted by Na-O and/or O-H...O interactions.

PubMed

Lü, Xing-Qiang; Jiang, Ji-Jun; Chen, Chun-Long; Kang, Bei-Sheng; Su, Cheng-Yong

2005-06-27

The reactions of Cu(II) with the mixed nitrilotriacetic acid (H3NTA) and 4,4'-bipyridyl (4,4'-bpy) ligands in different metal-to-ligand ratios in the presence of NaOH and NaClO4 afforded two complexes, Na3[Cu2(NTA)2(4,4'-bpy)]ClO4 x 5H2O (1) and [Cu2(NTA) (4,4'-bpy)2]ClO4 x 4H2O (2). The two complexes have been characterized by elemental analysis, IR, XRD, and single-crystal X-ray diffraction. 1 contains a basic doubly negatively charged [Cu2(NTA)2(4,4'-bpy)]2- dinuclear unit which was further assembled via multiple Na-O and O-H...O interactions into a three-dimensional (3D) pillared-layer structure. 2 features a two-dimensional (2D) undulated brick-wall architecture containing a basic doubly positively charged [Cu4(NTA)2(4,4'-bpy)2]2+ tetranuclear unit. The 2D network possesses large cavities hosting guest molecules and was further assembled via O-H...O hydrogen bonds into a 3D structure with several channels running in different directions.

Water oxidation catalyzed by the tetranuclear Mn complex [Mn(IV)4O5(terpy)4(H2O)2](ClO4)6.

PubMed

Gao, Yunlong; Crabtree, Robert H; Brudvig, Gary W

2012-04-02

The tetranuclear manganese complex [Mn(IV)(4)O(5)(terpy)(4)(H(2)O)(2)](ClO(4))(6) (1; terpy = 2,2':6',2″-terpyridine) gives catalytic water oxidation in aqueous solution, as determined by electrochemistry and GC-MS. Complex 1 also exhibits catalytic water oxidation when adsorbed on kaolin clay, with Ce(IV) as the primary oxidant. The redox intermediates of complex 1 adsorbed on kaolin clay upon addition of Ce(IV) have been characterized by using diffuse reflectance UV/visible and EPR spectroscopy. One of the products in the reaction on kaolin clay is Mn(III), as determined by parallel-mode EPR spectroscopic studies. When 1 is oxidized in aqueous solution with Ce(IV), the reaction intermediates are unstable and decompose to form Mn(II), detected by EPR spectroscopy, and MnO(2). DFT calculations show that the oxygen in the mono-μ-oxo bridge, rather than Mn(IV), is oxidized after an electron is removed from the Mn(IV,IV,IV,IV) tetramer. On the basis of the calculations, the formation of O(2) is proposed to occur by reaction of water with an electrophilic manganese-bound oxyl radical species, (•)O-Mn(2)(IV/IV), produced during the oxidation of the tetramer. This study demonstrates that [Mn(IV)(4)O(5)(terpy)(4)(H(2)O)(2)](ClO(4))(6) may be relevant for understanding the role of the Mn tetramer in photosystem II.

A π-π 3D network of tetranuclear μ2/μ3-carbonato Dy(III) bis-pyrazolylpyridine clusters showing single molecule magnetism features.

PubMed

Gass, Ian A; Moubaraki, Boujemaa; Langley, Stuart K; Batten, Stuart R; Murray, Keith S

2012-02-18

2,6-Di(pyrazole-3-yl)pyridine, 3-bpp, forms a porous (4(9)·6(6)) π-π mediated 3D network of trigonal pyramidal [Dy(III)(4)] carbonato-bridged complexes, with hexagonal channels comprising 54% of the unit cell volume, the material displaying slow magnetisation reversal. This journal is © The Royal Society of Chemistry 2012

Theoretical Modeling of the Magnetic Behavior of Thiacalix[4]arene Tetranuclear Mn(II)2Gd(III)2 and Co(II)2Eu(III)2 Complexes.

PubMed

Aldoshin, Sergey M; Sanina, Nataliya A; Palii, Andrew V; Tsukerblat, Boris S

2016-04-04

In view of a wide perspective of 3d-4f complexes in single-molecule magnetism, here we propose an explanation of the magnetic behavior of the two thiacalix[4]arene tetranuclear heterometallic complexes Mn(II)2Gd(III)2 and Co(II)2Eu(III)2. The energy pattern of the Mn(II)2Gd(III)2 complex evaluated in the framework of the isotropic exchange model exhibits a rotational band of the low-lying spin excitations within which the Landé intervals are affected by the biquadratic spin-spin interactions. The nonmonotonic temperature dependence of the χT product observed for the Mn(II)2Gd(III)2 complex is attributed to the competitive influence of the ferromagnetic Mn-Gd and antiferromagnetic Mn-Mn exchange interactions, the latter being stronger (J(Mn, Mn) = -1.6 cm(-1), Js(Mn, Gd) = 0.8 cm(-1), g = 1.97). The model for the Co(II)2Eu(III)2 complex includes uniaxial anisotropy of the seven-coordinate Co(II) ions and an isotropic exchange interaction in the Co(II)2 pair, while the Eu(III) ions are diamagnetic in their ground states. Best-fit analysis of χT versus T showed that the anisotropic contribution (arising from a large zero-field splitting in Co(II) ions) dominates (weak-exchange limit) in the Co(II)2Eu(III)2 complex (D = 20.5 cm(-1), J = -0.4 cm(-1), gCo = 2.22). This complex is concluded to exhibit an easy plane of magnetization (arising from the Co(II) pair). It is shown that the low-lying part of the spectrum can be described by a highly anisotropic effective spin-(1)/2 Hamiltonian that is deduced for the Co(II)2 pair in the weak-exchange limit.

Synthesis, structure and reactivity of tetranuclear square-type complexes of rhenium and manganese bearing pyrimidine-2-thiolate (pymS) ligands: versatile and efficient precursors for mono- and polynuclear compounds containing M(CO)(3) (M = Re, Mn) fragments.

PubMed

Kabir, S E; Alam, J; Ghosh, S; Kundu, K; Hogarth, G; Tocher, D A; Hossain, G M G; Roesky, H W

2009-06-21

Reactions of M(2)(CO)(10) (M = Re, Mn) with pyrimidine-2-thiol (pymSH) in the presence of Me(3)NO afford the tetranuclear square-type complexes [M(4)(CO)(12)(micro-kappa(3)-pymS)(4)] (, M = Re; , M = Mn). Both consist of four M(CO)(3) (M = Re, Mn) units, pairs of which are joined by tridentate pyrimidine-2-thiolate ligands. Treatment of with a variety of donor ligands results in cleavage of the square to afford mononuclear species with either a mono- or bidentate pyrimidine-2-thiolate ligand. Triphenylphosphine reacts with to give [Mn(CO)(3)(PPh(3))(kappa(2)-pymS)] () in which the pyrimidine-2-thiolate coordinates in a bidentate fashion. With diamines [M(CO)(3)(kappa(2)-L)(kappa(1)-pymS)] () (M = Re, Mn; L = 2,2'- bipy, 1,10-phen, en) result in which the pyrimidine-2-thiolate binds in a monodentate fashion through sulfur. With diphosphines, complexes with different stoichiometries and pyrimidine-2-thiolate binding modes are obtained depending on the nature of the metal and diphosphine. With dppm and dppe, gives [Re(CO)(2)(kappa(1)-pymS)(kappa(2)-dppm)] () and [Re(CO)(2)(kappa(2)-pymS)(kappa(1)-dppe)(2)] (), respectively, whereas affords [Mn(CO)(2)(kappa(2)-pymS)(kappa(1)-dppm)(2)] () and [Mn(CO)(2)(kappa(2)-pyS)(kappa(2)-dppe)] () under similar conditions. Reactions of with [Os(3)(CO)(10)(NCMe)(2)] affords mixed-metal butterfly clusters [MOs(3)(CO)(13)(micro(3)-kappa(2)-pymS)] () in which the group 7 metal occupies a wing-tip position and the pyrimidine-2-thiolate ligand caps a triangular Os(2)M face. With Ru(3)(CO)(12), carbon-sulfur bond cleavage occurs to give the tetranuclear clusters [MRu(3)(CO)(14)(micro(4)-S)(micro-kappa(1):eta(1)-pym)] () bearing both the extruded sulfur and the heterocyclic ring. The molecular structures of , and have been established by X-ray diffraction allowing the binding mode of the pyrimidine-2-thiolate ligands to be probed.

Metallohydrolase biomimetics with catalytic and structural flexibility.

PubMed

Mendes, Luisa L; Englert, Daniel; Fernandes, Christiane; Gahan, Lawrence R; Schenk, Gerhard; Horn, Adolfo

2016-11-22

The structural and functional properties of zinc(ii) complexes of two nitrogen rich polydentate ligands, HTPDP = 1,3-bis(bis-pyridin-2-ylmethylamino)propan-2-ol and HTPPNOL = N,N,N'-tris-(2-pyridylmethyl)-1,3-diaminopropan-2-ol, are compared. HTPDP is a hepta-dentate ligand with four pyridyl groups attached to a 1,3-diaminopropan-2-ol backbone while HTPPNOL contains only three pyridyl groups. In reactions with Zn(ClO 4 ) 2 , HTPDP forms a dinuclear zinc compound [Zn 2 (TPDP)(OAc)](ClO 4 ) 2 , 1. On the other hand, mononuclear [Zn(HTPPNOL)](ClO 4 ) 2 , 2, and tetranuclear [Zn 4 (TPPNOL) 2 (OAc) 3 ](ClO 4 ) 3 , 3, complexes were isolated with the ligand HTPPNOL. Kinetic measurements with the substrate bis(2,4-dinitrophenyl)phosphate (BDNPP) revealed that compound 1 (k cat = 31.4 × 10 -3 min -1 ) is more reactive than 3 (k cat = 7.7 × 10 -3 min -1 ) at pH = 8.5, whilst the mononuclear compound 2 is inactive. Compound 1 displays a typical steady-state kinetic behaviour, while compound 3 exhibits steady-state behaviour only ∼120 s after starting the reaction, preceded by a burst-phase. 31 P NMR studies confirm that 1 can promote the hydrolysis of both ester bonds in BDNPP, generating the monoester DNPP and inorganic phosphate in the process. In contrast, DNPP is not a substrate for 3. The crystal structure of the complex formed by 3 and DNPP reveals the formation of a tetranuclear zinc complex [Zn 4 (TPPNOL) 2 (DNPP) 2 ](ClO 4 ) 2 , 4, in which the phosphate moiety of DNPP adopts an unusual tridentate μ-η 1 :η 1 :η 1 coordination mode.

Syntheses, crystal structures and properties of series of 4d–4f ln(III)–Ag(I) heterometallic coordination polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ran, Xing-Rui; Wang, Ning; Xie, Wei-Ping

2015-05-15

By control of the experimental parameters such as ligands, pH value and reacting temperature, series of three-dimensional (3D) 4d–4f Ln(III)–Ag(I) porous coordination polymers (PCPs) with interesting chain-layer construction, namely, ([Ln{sup III}Ag{sup I}(na)(ina)(ox)]·2(H{sub 2}O)){sub n} [Ln=Sm(1), Eu(2), Gd(3), Tb(4), Dy(5), Ho(6), Y(7), Yb(8)], have been successfully synthesized under hydrothermal conditions and structurally characterized. All the complexes are characterized by elemental analyses, FT-IR spectroscopy, Powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Furthermore, the luminescence properties of compounds 2 and 4 and the magsnetic properties of complexes 3 and 5 were also investigated in detail. - Graphical abstract: Series of three-dimensional (3D)more » 4d–4f Ln(III)–Ag(I) porous coordination polymers (PCPs) with interesting chain-layer construction which are featured by tetranuclear Ln{sub 2}Ag{sub 2} and ‘non-linear’ N–Ag–N linkages. - Highlights: • Complexes 1–8 are first built by three kinds of organic ligands based on nicotinic acid and isonicotinic acid. • PCPs 1–8 are featured by tetranuclear Ln{sub 2}Ag{sub 2} and ‘non-linear’ N–Ag–N linkages. • The total solvent-accessible volume of PCP 2 comprises 11.6% of the crystal volume after dislodging the free water molecules. • Complexes 2 and 4 exhibit characteristic lanthanide-centered luminescence, while compounds 3 and 5 show antiferromagnetic behaviors.« less

Characterisation of [Cu4S], the catalytic site in nitrous oxide reductase, by EPR spectroscopy.

PubMed

Oganesyan, Vasily S; Rasmussen, Tim; Fairhurst, Shirley; Thomson, Andrew J

2004-04-07

The enzyme nitrous oxide reductase (N(2)OR) has a unique tetranuclear copper centre [Cu(4)S], called Cu(Z), at the catalytic site for the two-electron reduction of N(2)O to N(2). The X- and Q-band EPR spectra have been recorded from two forms of the catalytic site of the enzyme N(2)OR from Paracoccus pantotrophus, namely, a form prepared anaerobically, Cu(Z), that undergoes a one-electron redox cycle and Cu(Z)*, prepared aerobically, which cannot be redox cycled. The spectra of both species are axial with that of Cu(Z) showing a rich hyperfine splitting in the g||-region at X-band. DFT calculations were performed to gain insight into the electronic configuration and ground-state properties of Cu(Z) and to calculate EPR parameters. The results for the oxidation state [Cu(+1)(3)Cu(+2)(1)S](3+) are in good agreement with values obtained from the fitting of experimental spectra, confirming the absolute oxidation state of Cu(Z). The unpaired spin density in this configuration is delocalised over four copper ions, thus, Cu(I) 20.1%, Cu(II) 9.5%, Cu(III) 4.8% and Cu(IV) 9.2%, the mu(4)-sulfide ion and oxygen ligand. The three copper ions carrying the highest spin density plus the sulfide ion lie approximately in the same plane while the fourth copper ion is perpendicular to this plane and carries only 4.8% spin density. It is suggested that the atoms in this plane represent the catalytic core of Cu(Z), allowing electron redistribution within the plane during interaction with the substrate, N(2)O.

Highly preorganized pyrazolate-bridged palladium(II) and nickel(II) complexes in bimetallic norbornene polymerization.

PubMed

Sachse, Anna; Demeshko, Serhiy; Dechert, Sebastian; Daebel, Venita; Lange, Adam; Meyer, Franc

2010-04-28

New derivatives of pyrazolate-based binucleating ligands HL with appended imine functions have been synthesized to provide a versatile set of ligand systems with different backbone substituents both at the pyrazole-C(4) and the imine-C (H, Me, Ph). These scaffolds have two adjacent coordination compartments akin to the alpha-diimine type. A series of binuclear palladium(II) complexes [LPd(2)Cl(3)] (1-4) and tetranuclear nickel(II) complexes [L(2)Ni(4)Br(6)(solvent)(4)] (5, 6) of the various ligands have been prepared and characterized, including X-ray structural analyses for two representative Pd and the two Ni complexes. Complexes 5 and 6 were found to contain an unusual central mu(4)-bromide. Mononuclear nickel(II) complexes [L(2)Ni] were detected as intermediates in the formation of the tetranuclear complexes and have been characterized by X-ray analyses in two cases (7, 8). The interconversion between 5' and 7 has been investigated by UV/Vis spectroscopy and ESI mass spectrometry, and magnetic coupling in the [L(2)Ni(4)Br(6)(solvent)(4)] complexes has been studied (SQUID). Trans-coupling via the central mu(4)-bromide is suggested to mediate significant antiferromagnetic interaction. The reactivity of such types of Pd and Ni complexes has been tested for the vinyl/addition polymerization of norbornene. In the presence of an excess of cocatalyst methylaluminoxane (MAO) the palladium complexes show high activity up to 5.9 x 10(6) g(PNB) mol(Pd)(-1) h(-1) at 20 degrees C, while activities of the nickel systems are much lower, but strongly solvent dependent. Detailed studies on the dependence of activity on polymerization conditions such as molar ratios of catalyst and cocatalyst, temperature, reaction time and solvent were carried out. All obtained polynorbornenes (PNB) were noncrystalline and insoluble, but have high glass transition temperatures (T(g)). Microstructures were analyzed by IR spectroscopy and solid state (CP/MAS) (13)C NMR, revealing distinct patterns for the PNB produced by Ni- or Pd-catalysts. Structure/activity correlations deduced for the complexes with different ligand systems suggest that activities and polymer microstructures depend rather on the metal type than on ligand intricacies.

Oligo-m-phenyleneoxalamide copper(II) mesocates as electro-switchable ferromagnetic metal-organic wires.

PubMed

Pardo, Emilio; Ferrando-Soria, Jesús; Dul, Marie-Claire; Lescouëzec, Rodrigue; Journaux, Yves; Ruiz-García, Rafael; Cano, Joan; Julve, Miguel; Lloret, Francesc; Cañadillas-Delgado, Laura; Pasán, Jorge; Ruiz-Pérez, Catalina

2010-11-15

Double-stranded copper(II) string complexes of varying nuclearity, from di- to tetranuclear species, have been prepared by the Cu(II)-mediated self-assembly of a novel family of linear homo- and heteropolytopic ligands that contain two outer oxamato and either zero (1 b), one (2 b), or two (3 b) inner oxamidato donor groups separated by rigid 2-methyl-1,3-phenylene spacers. The X-ray crystal structures of these Cu(II) (n) complexes (n=2 (1 d), 3 (2 d), and 4 (3 d)) show a linear array of metal atoms with an overall twisted coordination geometry for both the outer CuN(2)O(2) and inner CuN(4) chromophores. Two such nonplanar all-syn bridging ligands 1 b-3 b in an anti arrangement clamp around the metal centers with alternating M and P helical chiralities to afford an overall double meso-helicate-type architecture for 1 d-3 d. Variable-temperature (2.0-300 K) magnetic susceptibility and variable-field (0-5.0 T) magnetization measurements for 1 d-3 d show the occurrence of S=nS(Cu) (n=2-4) high-spin ground states that arise from the moderate ferromagnetic coupling between the unpaired electrons of the linearly disposed Cu(II) ions (S(Cu)=1/2) through the two anti m-phenylenediamidate-type bridges (J values in the range of +15.0 to 16.8 cm(-1)). Density functional theory (DFT) calculations for 1 d-3 d evidence a sign alternation of the spin density in the meta-substituted phenylene spacers in agreement with a spin polarization exchange mechanism along the linear metal array with overall intermetallic distances between terminal metal centers in the range of 0.7-2.2 nm. Cyclic voltammetry (CV) and rotating-disk electrode (RDE) electrochemical measurements for 1 d-3 d show several reversible or quasireversible one- or two-electron steps that involve the consecutive metal-centered oxidation of the inner and outer Cu(II) ions (S(Cu)=1/2) to diamagnetic Cu(III) ones (S(Cu)=0) at relatively low formal potentials (E values in the range of +0.14 to 0.25 V and of +0.43 to 0.67 V vs. SCE, respectively). Further developments may be envisaged for this family of oligo-m-phenyleneoxalamide copper(II) double mesocates as electroswitchable ferromagnetic 'metal-organic wires' (MOWs) on the basis of their unique ferromagnetic and multicenter redox behaviors.

What Controls the Magnetic Exchange and Anisotropy in a Family of Tetranuclear {Mn2IIMn2III} Single-Molecule Magnets?

PubMed

Vignesh, Kuduva R; Langley, Stuart K; Gartshore, Christopher J; Moubaraki, Boujemaa; Murray, Keith S; Rajaraman, Gopalan

2017-02-20

Twelve heterovalent, tetranuclear manganese(II/III) planar diamond or "butterfly" complexes, 1-12, have been synthesized and structurally characterized, and their magnetic properties have been probed using experimental and theoretical techniques. The 12 structures are divided into two distinct "classes". Compounds 1-8 place the Mn(III), S = 2, ions in the body positions of the butterfly metallic core, while the Mn(II), S = 5/2, ions occupy the outer wing sites and are described as "Class 1". Compounds 9-12 display the reverse arrangement of ions and are described as "Class 2". Direct current susceptibility measurements for 1-12 reveal ground spin states ranging from S = 1 to S = 9, with each complex displaying unique magnetic exchange parameters (J). Alternating current susceptibility measurements found that that slow magnetic relaxation is observed for all complexes, except for 10 and 12, and display differing anisotropy barriers to magnetization reversal. First, we determined the magnitude of the magnetic exchange parameters for all complexes. Three exchange coupling constants (J bb , J wb , and J ww ) were determined by DFT methods which are found to be in good agreement with the experimental fits. It was found that the orientation of the Jahn-Teller axes and the Mn-Mn distances play a pivotal role in determining the sign and strength of the J bb parameter. Extensive magneto-structural correlations have been developed for the two classes of {Mn II 2 Mn III 2 } butterfly complexes by varying the Mn b -O distance, Mn w -O distance, Mn b -O-Mn b angle (α), Mn b -O-Mn b -O dihedral angle (γ), and out-of-plane shift of the Mn w atoms (β). For the magnetic anisotropy the DFT calculations yielded larger negative D value for complexes 2, 3, 4, and 6 compared to the other complexes. This is found to be correlated to the electron-donating/withdrawing substituents attached to the ligand moiety and suggests a possible way to fine tune the magnetic anisotropy in polynuclear Mn ion complexes.

Synthesis, characterization, and reactivity studies of heterodinuclear complexes modeling active sites in purple acid phospatases.

PubMed

Jarenmark, Martin; Haukka, Matti; Demeshko, Serhiy; Tuczek, Felix; Zuppiroli, Luca; Meyer, Franc; Nordlander, Ebbe

2011-05-02

To model the heterodinuclear active sites in plant purple acid phosphatases, a mononuclear synthon, [Fe(III)(H(2)IPCPMP)(Cl(2))][PF(6)] (1), has been generated in situ from the ligand 2-(N-isopropyl-N-((2-pyridyl)methyl)aminomethyl)-6-(N-(carboxylmethyl)-N-((2-pyridyl)methyl)amino methyl)-4-methylphenol (IPCPMP) and used to synthesize heterodinuclear complexes of the formulas [Fe(III)M(II)(IPCPMP)(OAc)(2)(CH(3)OH)][PF(6)] (M = Zn (2), Co (3), Ni (4), Mn (5)), [Fe(III)Zn(II)(IPCPMP)(mpdp)][PF(6)] (6) (mpdp = meta-phenylene-dipropionate), and [Fe(III)Cu(II)(IPCPMP) (OAc)}(2)(μ-O)][PF(6)] (7). Complexes 2-4, 6, and 7 have been crystallographically characterized. The structure of 6 is a solid state coordination polymer with heterodinuclear monomeric units, and 7 is a tetranuclear complex consisting of two heterodinuclear phenolate-bridged Fe(III)Cu(II) units bridged through a μ-oxido group between the two Fe(III) ions. Mössbauer spectra confirm the presence of high spin Fe(III) in an octahedral environment for 1, 3, and 5 while 2 and 4 display relaxation effects. Magnetic susceptibility measurements indicate weak antiferromagnetic coupling for 3, 4, and 5 and confirm the assignment of the metal centers in 2-5 as high spin Fe(III)-M(II) (M = Zn, Co (high spin), Ni (high spin), Mn (high spin)). Complexes 2-5 are intact in acetonitrile solution as indicated by IR spectroscopy (for 2-4) and electrospray ionization mass spectrometry (ESI-MS) but partly dissociate to hydroxide species and a mononuclear complex in water/acetonitrile solutions. UV-vis spectroscopy reveal pH-dependent behavior, and species that form upon increasing the pH have been assigned to μ-hydroxido-bridged Fe(III)M(II) complexes for 2-5 although 2 and 3 is further transformed into what is propsed to be a μ-oxido-bridged tetranuclear complex similar to 7. Complexes 2-5 enhance phosphodiester cleavage of 2-hydroxy-propyl-p-nitrophenyl phosphate (HPNP) and bis(2,4-dinitrophenyl)phosphate (BDNPP), but the reactivities are different for different complexes and generally show strong pH dependence. © 2011 American Chemical Society

A new (4, 6)-connected Cu(I) coordination polymer based on rare tetranuclear [Cu4I2] clusters: Synthesis, crystal structure, luminescent and photocatalytic properties

NASA Astrophysics Data System (ADS)

Cui, Li-Jing; Liu, Chun-Yan; Bian, Ming; Yu, Li-Jun

2018-03-01

A new Cu(I) coordination polymer, namely [Cu5I3(L)2]n (1 HL = 3-(4-pyridyl)-5-(3-pyridyl)-1,2,4-triazolyl), was solvothermally synthesized using CuI, HL and NaI as the starting materials. Single crystal X-ray structural analysis shows that compound 1 features a (4, 6)-connected 3D framework employing rare tetranuclear [Cu4I2] clusters as building subunits. It exhibits intense metal-to-ligand luminescence and excellent photocatalytic activity on degradation of methylene blue (MB).

A two-dimensional hydrogen-bonded water layer in the structure of a cobalt(III) cubane complex.

PubMed

Qi, Ji; Zhai, Xiang-Sheng; Zhu, Hong-Lin; Lin, Jian-Li

2014-02-01

A tetranuclear Co(III) oxide complex with cubane topology, tetrakis(2,2'-bipyridine-κ(2)N,N')di-μ2-carbonato-κ(4)O:O'-tetra-μ3-oxido-tetracobalt(III) pentadecahydrate, [Co4(CO3)2O4(C10H8N2)4]·15H2O, with an unbounded hydrogen-bonded water layer, has been synthesized by reaction of CoCO3 and 2,2'-bipyridine. The solvent water molecules form a hydrogen-bonded net with tetrameric and pentameric water clusters as subunits. The Co4O4 cubane-like cores are sandwiched between the water layers, which are further stacked into a three-dimensional metallo-supramolecular network.

Heterometallic and homometallic complexes containing bifunctional ligands and their application in high-temperature oxide superconductor materials

NASA Astrophysics Data System (ADS)

Breeze, Steven R.

We have been interested in the development of soluble precursors for the production of YBasb2Cusb3Osb{7-delta} and Bisb2(Ca,Sr)sbn+1CusbnOsb(2n + 4) + delta, superconductor materials. Several heterometallic and homometallic complexes containing the constituent metals of these superconductors and bifunctional ligands such as aminoalcohols, acetates and thioethers have been isolated and structurally characterized. The thermal decomposition properties and magnetic properties of some of these compounds have been investigated. The first ligand system investigated involved 1,3-bis(dimethylamino)-2-propanol (bdmapH). By varying the ratio of bdmapH, Cu(OCHsb3)sb2, and M(Osb2CCFsb3)sb2 (M = Ca, Sr) several heterometallic complexes have been obtained, including Srsb2Cusb2(bdmap)sb4(Osb2CCFsb3)sb4, CaCu(bdmap)sb2(Osb2CCFsb3)sb3(Hsb2O), Srsb2Cusb4(bdmap)sb6-(Osb2CCFsb3)sb4(musb 3-OH)sb2(THF)sb2 and SrCusb2(bdmap)sb3(Osb2CCFsb3)sb3(THF). With the exception of Srsb2Cusb4(bdmap)sb6(Osb2CCFsb3)sb4(musb 3-OH)sb2(THF)sb2, these compounds thermally decompose to form mixtures of fluorides and oxides. An analogous acetate compound SrCusb2(bdmap)sb3(Osb2CCHsb3)sb3(THF) has been produced, which forms the corresponding oxide at high temperature. A bismuth dimer, Bisb2(bdmap)sb2(Osb2CCHsb3)sb4(Hsb2O), has also been obtained. Superconducting powder of the Bisb2Srsb2CaCusb2Osb{8 + delta} and epitaxial superconducting films of the YBasb2Cusb3Osb{7-delta} superconductor have been produced using the bdmap and acetate ligands as cross-linking reagents. The second ligand system investigated involved di-2-pyridylmethanediol. Only homonuclear complexes have been obtained by using this ligand, including the mononuclear compound Cu ((2-py)sb2CO(OH)) sb2(HOsb2CCH sb3)sb2*CHsb2Clsb2, the tetranuclear compound Cusb4 ((2-py)sb2CO(OH)) sb2(Osb2CCHsb 3)sb6(Hsb2O)sb2*CHsb2Clsb2, and the bismuth dimer Bisb2 ((2-py)sb2CO(OH)) sb2(Osb 2CCFsb3)sb4*(THF)sb2. The tetranuclear Cusb4 compound was found to be dominated by ferromagnetic exchanges. The third ligand system examined involved 2,2sp'-thiodiethanol (tdeHsb2). Heterometallic complexes Prsb2Cusb4(tde)sb3(tdeH)sb2(hfacac)sb4(musb6 -O) and Basb2Cusb2(tdeH)sb4(hfacac)sb4 have been obtained using this ligand. The six metal centers in Prsb2Cusb4(tde)sb3(tdeH)sb2(hfacac)sb4(musb6-O) are arranged in a octahedron and are linked by musb6-oxide and 2,2sp'-thiodiethanolato ligands. A metallomacrocyclic Cusb4 compound, Cusb4(tde)sb2(hfacac)sb4 has been produced. Attempts have been made to produce bismuthine complexes with an amino or pyridyl functional group that can coordinate to copper. The reaction of 4-Li-Csb6Hsb4CHsb2N(2-PY)sb2 with BiClsb3 produces the compound BispIII (p-Csb6Hsb4CHsb2N(2-py)sb2rbracksb3. The ability of this compound to coordinate CuClsb2 has been investigated. The complex BispV (p-Csb6Hsb4CHsb2N(2-py)sb2rbracksb3(Osb2CCHsb3)sb2 has also been produced.

Dilution-triggered SMM behavior under zero field in a luminescent Zn2Dy2 tetranuclear complex incorporating carbonato-bridging ligands derived from atmospheric CO2 fixation.

PubMed

Titos-Padilla, Silvia; Ruiz, José; Herrera, Juan Manuel; Brechin, Euan K; Wersndorfer, Wolfgang; Lloret, Francesc; Colacio, Enrique

2013-08-19

The synthesis, structure, magnetic, and luminescence properties of the Zn2Dy2 tetranuclear complex of formula {(μ3-CO3)2[Zn(μ-L)Dy(NO3)]2}·4CH3OH (1), where H2L is the compartmental ligand N,N',N″-trimethyl-N,N″-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine, are reported. The carbonate anions that bridge two Zn(μ-L)Dy units come from the atmospheric CO2 fixation in a basic medium. Fast quantum tunneling relaxation of the magnetization (QTM) is very effective in this compound, so that single-molecule magnet (SMM) behavior is only observed in the presence of an applied dc field of 1000 Oe, which is able to partly suppress the QTM relaxation process. At variance, a 1:10 Dy:Y magnetic diluted sample, namely, 1', exhibits SMM behavior at zero applied direct-current (dc) field with about 3 times higher thermal energy barrier than that in 1 (U(eff) = 68 K), thus demonstrating the important role of intermolecular dipolar interactions in favoring the fast QTM relaxation process. When a dc field of 1000 Oe is applied to 1', the QTM is almost fully suppressed, the reversal of the magnetization slightly slows, and U(eff) increases to 78 K. The dilution results combined with micro-SQUID magnetization measurements clearly indicate that the SMM behavior comes from single-ion relaxation of the Dy(3+) ions. Analysis of the relaxation data points out that a Raman relaxation process could significantly affect the Orbach relaxation process, reducing the thermal energy barrier U(eff) for slow relaxation of the magnetization.

The catalytic cycle of nitrous oxide reductase - The enzyme that catalyzes the last step of denitrification.

PubMed

Carreira, Cíntia; Pauleta, Sofia R; Moura, Isabel

2017-12-01

The reduction of the potent greenhouse gas nitrous oxide requires a catalyst to overcome the large activation energy barrier of this reaction. Its biological decomposition to the inert dinitrogen can be accomplished by denitrifiers through nitrous oxide reductase, the enzyme that catalyzes the last step of the denitrification, a pathway of the biogeochemical nitrogen cycle. Nitrous oxide reductase is a multicopper enzyme containing a mixed valence CuA center that can accept electrons from small electron shuttle proteins, triggering electron flow to the catalytic sulfide-bridged tetranuclear copper "CuZ center". This enzyme has been isolated with its catalytic center in two forms, CuZ*(4Cu1S) and CuZ(4Cu2S), proven to be spectroscopic and structurally different. In the last decades, it has been a challenge to characterize the properties of this complex enzyme, due to the different oxidation states observed for each of its centers and the heterogeneity of its preparations. The substrate binding site in those two "CuZ center" forms and which is the active form of the enzyme is still a matter of debate. However, in the last years the application of different spectroscopies, together with theoretical calculations have been useful in answering these questions and in identifying intermediate species of the catalytic cycle. An overview of the spectroscopic, kinetics and structural properties of the two forms of the catalytic "CuZ center" is given here, together with the current knowledge on nitrous oxide reduction mechanism by nitrous oxide reductase and its intermediate species. Copyright © 2017 Elsevier Inc. All rights reserved.

A series of new copper iodobismuthates: structural relationships, optical band gaps affected by dimensionality, and distinct thermal stabilities.

PubMed

Chai, Wen-Xiang; Wu, Li-Ming; Li, Jun-Qian; Chen, Ling

2007-10-15

Three new copper iodobismuthates, red tetranuclear [n-Bu(4)N][Cu(2)(CH(3)CN)(2)Bi(2)I(10)] (1), dark-red infinite linear [Et(4)N](2n)[Cu(2)Bi(2)I(10)](n) (2), and black polymeric ladderlike [Cu(CH(3)CN)(4)](2n)[Cu(2)Bi(2)I(10)](n) (3), crystallize from solutions of BiI3 and CuI in the presence of different cations. A regular structural relationship from 0-D (1) to 1-D linear anion chains (2) to 1-D ladderlike anion chains (3) is observed. The self-assembly of the basic building unit Cu(2)Bi(2)I(10) as altered by different cations is proposed to be the driving force for their formation. The optical band gaps exhibit a structure-related decrease from 1 to 2/3, in agreement with their color changes and the density functional theory (DFT) calculation results. The electronic structures and the relationship with corresponding monobismuth analogues and the Ag-Bi isotypes are discussed on the basis of DFT calculations. In spite of their structural similarities, the compounds are distinctive thermally: 2 is stable to 230 degrees C, 1 undergoes a solvent loss at 85 degrees C to form a new phase that is thermally stable to 230 degrees C, and 3 releases a solvent molecule and decomposes at 80 degrees C into BiI(3) and CuI. The essential reasons for these differences are discussed.

Leaching behavior and chemical stability of copper butyl xanthate complex under acidic conditions.

PubMed

Chang, Yi Kuo; Chang, Juu En; Chiang, Li Choung

2003-08-01

Although xanthate addition can be used for treating copper-containing wastewater, a better understanding of the leaching toxicity and the stability characteristics of the copper xanthate complexes formed is essential. This work was undertaken to evaluate the leaching behavior of copper xanthate complex precipitates by means of toxicity characteristics leaching procedure (TCLP) and semi-dynamic leaching test (SDLT) using 1 N acetic acid solution as the leachant. Also, the chemical stability of the copper xanthate complex during extraction has been examined with the studying of variation of chemical structure using UV-vis, Fourier transform infrared and X-ray photoelectron spectroscopies (XPS). Both TCLP and SDLT results showed that a negligible amount of copper ion was leached out from the copper xanthate complex precipitate, indicating that the complex exhibited a high degree of copper leaching stability under acidic conditions. Nevertheless, chemical structure of the copper xanthate complex precipitate varied during the leaching tests. XPS data suggested that the copper xanthate complex initially contained both cupric and cuprous xanthate, but the unstable cupric xanthate change to the cuprous form after acid extraction, indicating the cuprous xanthate to be the final stabilizing structure. Despite that, the changes of chemical structure did not induce the rapid leaching of copper from the copper xanthate complex.

XAFS Study of the Ferro- and Antiferromagnetic Binuclear Copper(II) Complexes of Azomethine Based Tridentate Ligands

NASA Astrophysics Data System (ADS)

Vlasenko, Valery G.; Vasilchenko, Igor S.; Pirog, Irina V.; Shestakova, Tatiana E.; Uraev, Ali I.; Burlov, Anatolii S.; Garnovskii, Alexander D.

2007-02-01

Binuclear copper complexes are known to be models for metalloenzymes containing copper active sites, and some of them are of considerable interest due to their magnetic and charge transfer properties. The reactions of the complex formation of bibasic tridentate heterocyclic imines with copper acetate leads to two types of chelates with mono deprotonated ligands and with totally deprotonated ligands. Cu K-edge EXAFS has been applied to determine the local structure around the metal center in copper(II) azomethine complexes with five tridentate ligands: 1-(salycilideneimino)- or 1-(2-tosylaminobenzilideneimino)-2-amino(oxo, thio)benzimidazoles. It has been found that some of the chelates studied are bridged binuclear copper complexes, and others are mononuclear complexes. The copper-copper interatomic distances in the bridged binuclear copper complexes were found to be 2.85-3.01 Å. Variable temperature magnetic susceptibility data indicate the presence of both ferromagnetic and antiferromagnetic interactions within the dimer, the former is dominating at low temperatures and the latter at high temperatures.

Development of Novel DNA Cleavage Systems Based on Copper Complexes. Synthesis and Characterisation of Cu(II) Complexes of Hydroxyflavones

PubMed Central

el Amrani, F. Ben-Allal; Perelló, L.; Torres, L.

2000-01-01

Copper(II) complexes of several hydroxyflavones were prepared and characterised through their physico-chemical properties. The nuclease activity of three synthesised complexes is reported. These copper(II) complexes present more nuclease activity than the ligands and the copper(II) ion. PMID:18475969

40 CFR 721.2577 - Copper complex of (substituted sulfonaphthyl azo substituted phenyl) disulfonaphthyl azo, amine...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Copper complex of (substituted... Copper complex of (substituted sulfonaphthyl azo substituted phenyl) disulfonaphthyl azo, amine salt... substances identified generically as copper complex of (substituted sulfonaphthyl azo substituted phenyl...

In vitro inhibition of hyaluronidase by sodium copper chlorophyllin complex and chlorophyllin analogs

PubMed Central

McCook, John P; Dorogi, Peter L; Vasily, David B; Cefalo, Dustin R

2015-01-01

Background Inhibitors of hyaluronidase are potent agents that maintain hyaluronic acid homeostasis and may serve as anti-aging, anti-inflammatory, and anti-microbial agents. Sodium copper chlorophyllin complex is being used therapeutically as a component in anti-aging cosmeceuticals, and has been shown to have anti-hyaluronidase activity. In this study we evaluated various commercial lots of sodium copper chlorophyllin complex to identify the primary small molecule constituents, and to test various sodium copper chlorophyllin complexes and their small molecule analog compounds for hyaluronidase inhibitory activity in vitro. Ascorbate analogs were tested in combination with copper chlorophyllin complexes for potential additive or synergistic activity. Materials and methods For hyaluronidase activity assays, dilutions of test materials were evaluated for hydrolytic activity of hyaluronidase by precipitation of non-digested hyaluronate by measuring related turbidity at 595 nm. High-performance liquid chromatography and mass spectroscopy was used to analyze and identify the primary small molecule constituents in various old and new commercial lots of sodium copper chlorophyllin complex. Results The most active small molecule component of sodium copper chlorophyllin complex was disodium copper isochlorin e4, followed by oxidized disodium copper isochlorin e4. Sodium copper chlorophyllin complex and copper isochlorin e4 disodium salt had hyaluronidase inhibitory activity down to 10 µg/mL. The oxidized form of copper isochlorin e4 disodium salt had substantial hyaluronidase inhibitory activity at 100 µg/mL but not at 10 µg/mL. Ascorbate derivatives did not enhance the hyaluronidase inhibitory activity of sodium copper chlorophyllin. Copper isochlorin e4 analogs were always the dominant components of the small molecule content of the commercial lots tested; oxidized copper isochlorin e4 was found in increased concentrations in older compared to newer lots tested. Conclusion These results support the concept of using the hyaluronidase inhibitory activity of sodium copper chlorophyllin complex to increase the hyaluronic acid level of the dermal extracellular matrix for the improvement of the appearance of aging facial skin. PMID:26300653

In vitro inhibition of hyaluronidase by sodium copper chlorophyllin complex and chlorophyllin analogs.

PubMed

McCook, John P; Dorogi, Peter L; Vasily, David B; Cefalo, Dustin R

2015-01-01

Inhibitors of hyaluronidase are potent agents that maintain hyaluronic acid homeostasis and may serve as anti-aging, anti-inflammatory, and anti-microbial agents. Sodium copper chlorophyllin complex is being used therapeutically as a component in anti-aging cosmeceuticals, and has been shown to have anti-hyaluronidase activity. In this study we evaluated various commercial lots of sodium copper chlorophyllin complex to identify the primary small molecule constituents, and to test various sodium copper chlorophyllin complexes and their small molecule analog compounds for hyaluronidase inhibitory activity in vitro. Ascorbate analogs were tested in combination with copper chlorophyllin complexes for potential additive or synergistic activity. For hyaluronidase activity assays, dilutions of test materials were evaluated for hydrolytic activity of hyaluronidase by precipitation of non-digested hyaluronate by measuring related turbidity at 595 nm. High-performance liquid chromatography and mass spectroscopy was used to analyze and identify the primary small molecule constituents in various old and new commercial lots of sodium copper chlorophyllin complex. The most active small molecule component of sodium copper chlorophyllin complex was disodium copper isochlorin e4, followed by oxidized disodium copper isochlorin e4. Sodium copper chlorophyllin complex and copper isochlorin e4 disodium salt had hyaluronidase inhibitory activity down to 10 µg/mL. The oxidized form of copper isochlorin e4 disodium salt had substantial hyaluronidase inhibitory activity at 100 µg/mL but not at 10 µg/mL. Ascorbate derivatives did not enhance the hyaluronidase inhibitory activity of sodium copper chlorophyllin. Copper isochlorin e4 analogs were always the dominant components of the small molecule content of the commercial lots tested; oxidized copper isochlorin e4 was found in increased concentrations in older compared to newer lots tested. These results support the concept of using the hyaluronidase inhibitory activity of sodium copper chlorophyllin complex to increase the hyaluronic acid level of the dermal extracellular matrix for the improvement of the appearance of aging facial skin.

Aspartate aminotransferase is potently inhibited by copper complexes: Exploring copper complex-binding proteome.

PubMed

Jia, Yuqi; Lu, Liping; Yuan, Caixia; Feng, Sisi; Zhu, Miaoli

2017-05-01

Recent researches indicated that a copper complex-binding proteome that potently interacted with copper complexes and then influenced cellular metabolism might exist in organism. In order to explore the copper complex-binding proteome, a copper chelating ion-immobilized affinity chromatography (Cu-IMAC) column and mass spectrometry were used to separate and identify putative Cu-binding proteins in primary rat hepatocytes. A total of 97 putative Cu-binding proteins were isolated and identified. Five higher abundance proteins, aspartate aminotransferase (AST), malate dehydrogenase (MDH), catalase (CAT), calreticulin (CRT) and albumin (Alb) were further purified using a SP-, and (or) Q-Sepharose Fast Flow column. The interaction between the purified proteins and selected 11 copper complexes and CuCl 2 was investigated. The enzymes inhibition tests demonstrated that AST was potently inhibited by copper complexes while MDH and CAT were weakly inhibited. Schiff-based copper complexes 6 and 7 potently inhibited AST with the IC 50 value of 3.6 and 7.2μM, respectively and exhibited better selectivity over MDH and CAT. Fluorescence titration results showed the two complexes tightly bound to AST with binding constant of 3.89×10 6 and 3.73×10 6 M -1 , respectively and a stoichiometry ratio of 1:1. Copper complex 6 was able to enter into HepG2 cells and further inhibit intracellular AST activity. Copyright © 2017 Elsevier Inc. All rights reserved.

Crystal structures of copper(II) chloride, copper(II) bromide, and copper(II) nitrate complexes with pyridine-2-carbaldehyde thiosemicarbazone

NASA Astrophysics Data System (ADS)

Chumakov, Yu. M.; Tsapkov, V. I.; Jeanneau, E.; Bairac, N. N.; Bocelli, G.; Poirier, D.; Roy, J.; Gulea, A. P.

2008-09-01

The crystal structures of chloro-(2-formylpyridinethiosemicarbazono)copper dimethyl sulfoxide solvate ( I), bromo-(2-formylpyridinethiosemicarbazono)copper ( II), and (2-formylpyridinethiosemicarbazono)copper(II) nitrate dimethyl sulfoxide solvate ( III) are determined using X-ray diffraction. In the crystals, complexes I and II form centrosymmetric dimers in which the thiosemicarbazone sulfur atom serves as a bridge and occupies the fifth coordination site of the copper atom of the neighboring complex related to the initial complex through the center of symmetry. In both cases, the coordination polyhedron of the complexing ion is a distorted tetragonal bipyramid. Complex III in the crystal structure forms polymer chains in which the copper atom of one complex forms the coordination bond with the thicarbamide nitrogen atom of the neighboring complex. In this structure, the coordination polyhedron of the central atom is an elongated tetragonal bipyramid. It is established that complexes I III at a concentration of 10-5 mol/l selectively inhibit the growth of 60 to 90 percent of the cancer tumor cells of the human myeloid leukemia (HL-60).

Identification of the iron-sulfur center of spinach ferredoxin-nitrite reductase as a tetranuclear center, and preliminary EPR studies of mechanism.

PubMed

Lancaster, J R; Vega, J M; Kamin, H; Orme-Johnson, N R; Orme-Johnson, W H; Krueger, R J; Siegel, L M

1979-02-25

EPR spectroscopic and chemical analyses of spinach nitrite reductase show that the enzyme contains one reducible iron-sulfur center, and one site for binding either cyanide or nitrite, per siroheme. The heme is nearly all in the high spin ferric state in the enzyme as isolated. The extinction coefficient of the enzyme has been revised to E386 = 7.6 X 10(4) cm-1 (M heme)-1. The iron-sulfur center is reduced with difficulty by agents such as reduced methyl viologen (equilibrated with 1 atm of H2 at pH 7.7 in the presence of hydrogenase) or dithionite. Complexation of the enzyme with CO (a known ligand for nitrite reductase heme) markedly increases the reducibility of the iron-sulfur center. New chemical analyses and reinterpretation of previous data show that the enzyme contains 6 mol of iron and 4 mol of acid-labile S2-/mol of siroheme. The EPR spectrum of reduced nitrite reductase in 80% dimethyl sulfoxide establishes clearly that the enzyme contains a tetranuclear iron-sulfur (Fe4S4) center. The ferriheme and Fe4S4 centers are reduced at similar rates (k = 3 to 4 s-1) by dithionite. The dithionite-reduced Fe4S4 center is rapidly (k = 100 s-1) reoxidized by nitrite. These results indicate a role for the Fe4S4 center in catalysis.

Effect of decomposition and organic residues on resistivity of copper films fabricated via low-temperature sintering of complex particle mixed dispersions

NASA Astrophysics Data System (ADS)

Yong, Yingqiong; Nguyen, Mai Thanh; Tsukamoto, Hiroki; Matsubara, Masaki; Liao, Ying-Chih; Yonezawa, Tetsu

2017-03-01

Mixtures of a copper complex and copper fine particles as copper-based metal-organic decomposition (MOD) dispersions have been demonstrated to be effective for low-temperature sintering of conductive copper film. However, the copper particle size effect on decomposition process of the dispersion during heating and the effect of organic residues on the resistivity have not been studied. In this study, the decomposition process of dispersions containing mixtures of a copper complex and copper particles with various sizes was studied. The effect of organic residues on the resistivity was also studied using thermogravimetric analysis. In addition, the choice of copper salts in the copper complex was also discussed. In this work, a low-resistivity sintered copper film (7 × 10-6 Ω·m) at a temperature as low as 100 °C was achieved without using any reductive gas.

21 CFR 73.2125 - Potassium sodium copper chlorophyllin (chlorophyllin-copper complex).

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Potassium sodium copper chlorophyllin... § 73.2125 Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). (a) Identity and specifications. The color additive potassium sodium copper chlorophyllin shall conform in identity and...

21 CFR 73.2125 - Potassium sodium copper chlorophyllin (chlorophyllin-copper complex).

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Potassium sodium copper chlorophyllin... § 73.2125 Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). (a) Identity and specifications. The color additive potassium sodium copper chlorophyllin shall conform in identity and...

21 CFR 73.2125 - Potassium sodium copper chlorophyllin (chlorophyllin-copper complex).

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Potassium sodium copper chlorophyllin... § 73.2125 Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). (a) Identity and specifications. The color additive potassium sodium copper chlorophyllin shall conform in identity and...

Synthesis, characterization and properties of copper(I) complexes with bis(diphenylphosphino)-ferrocene ancillary ligand

NASA Astrophysics Data System (ADS)

Liu, Xinfang; Zhang, Songlin; Ding, Yuqiang

2012-06-01

Three copper(I) complexes (2-4) containing dppf ancillary ligand (dppf = bis(diphenylphosphino)-ferrocene) were synthesized when chloride-bridged copper(I) complex 1 reacted with acetanilide and characterized by IR, element analysis and NMR spectrum. And the crystal structures of complexes 2 and 4 have been determined by X-ray diffraction method. Complex 2, an acetate-bridged copper(I) complex, was obtained under N2 atmosphere in un-dried solvent; the acetate ion came from the hydrolysis reaction of acetanilide due to residual water in solvent. Acetanilide was deprotonated and coordinated with the copper(I) centre to form a copper(I) amidate complex 3 when reacted in pre-dried solvent. In addition, a known complex 4, the oxidation product of dppf, was isolated from the same reaction system when reacted in air atmosphere. CV and TG experiments were carried out to check the electron transfer properties and thermal stabilities of complexes 2-3. Finally, the arylation reaction of complex 3 with iodobenzene was performed to study the reaction mechanism of copper(I) catalyzed Goldberg reaction.

Dimensional modulation and magnetic properties of triazole- and bis(triazole)-based copper(II) coordination polymers tuned by aromatic polycarboxylates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Ju-Wen; Zhao, Wei; Lu, Qi-Lin

2014-04-01

Five new metal–organic coordination polymers ([Cu{sub 3}(μ{sub 2}-OH){sub 2}(atrz){sub 2}(nph){sub 2}(H{sub 2}O){sub 2}]·2H{sub 2}O){sub n} (1), ([Cu{sub 2}(μ{sub 3}-OH)(atrz)(1,2,4-btc)]·2H{sub 2}O){sub n} (2), ([Cu{sub 2}(μ{sub 3}-OH)(atrz)(1,2,4-btc)(H{sub 2}O)]·H{sub 2}O){sub n} (3), [Cu(dth){sub 0.5}(nph)(H{sub 2}O)]{sub n} (4) and [Cu(dth)(Hnip){sub 2}]{sub n} (5) [atrz=4-amino-1,2,4-triazole, dth=N,N'-di(4H-1,2,4-triazole)hexanamide, H{sub 2}nph=3-nitrophthalic acid, 1,2,4-H{sub 3}btc=1,2,4-benzenetricarboxylic acid and H{sub 2}nip=5-nitroisophthalic acid] were hydrothermally synthesized and structurally characterized. Polymer 1 shows a one-dimensional (1D) chain. Polymers 2 and 3 exhibit similar tetranuclear Cu{sup II}{sub 4} cluster-based three-dimensional (3D) frameworks with the same components. Polymer 4 possesses a 3D framework with a 4{sup 12}·6{sup 3}-pcu topology. Polymer 5 displays a 3D frameworkmore » with a 4{sup 4}·6{sup 10}·8-mab topology. The magnetic properties of 1–4 were investigated. - Graphical abstract: Five triazole-based copper(II) polymers modulated by polycarboxylates were synthesized. Bis-triazole-bis-amide ligand and polycarboxylates play important roles in tuning dimensionality of polymers. Magnetic properties of polymers were investigated. - Highlights: • Five triazole- and bis(triazole)-based copper(II) coordination polymers tuned by aromatic polycarboxylates were obtained. • The aromatic polycarboxylates have an important influence on the dimensionality of five polymers. • The magnetic properties of four polymers were investigated.« less

21 CFR 73.1125 - Potassium sodium copper chloropyhllin (chlorophyllin-copper complex).

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Potassium sodium copper chloropyhllin....1125 Potassium sodium copper chloropyhllin (chlorophyllin-copper complex). (a) Identity. (1) The color additive potassium sodium copper chlorophyllin is a green to black powder obtained from chlorophyll by...

A peroxynitrite complex of copper: formation from a copper-nitrosyl complex, transformation to nitrite and exogenous phenol oxidative coupling or nitration.

PubMed

Park, Ga Young; Deepalatha, Subramanian; Puiu, Simona C; Lee, Dong-Heon; Mondal, Biplab; Narducci Sarjeant, Amy A; del Rio, Diego; Pau, Monita Y M; Solomon, Edward I; Karlin, Kenneth D

2009-11-01

Reaction of nitrogen monoxide with a copper(I) complex possessing a tridentate alkylamine ligand gives a Cu(I)-(*NO) adduct, which when exposed to dioxygen generates a peroxynitrite (O=NOO(-))-Cu(II) species. This undergoes thermal transformation to produce a copper(II) nitrito (NO(2) (-)) complex and 0.5 mol equiv O(2). In the presence of a substituted phenol, the peroxynitrite complex effects oxidative coupling, whereas addition of chloride ion to dissociate the peroxynitrite moiety instead leads to phenol ortho nitration. Discussions include the structures (including electronic description) of the copper-nitrosyl and copper-peroxynitrite complexes and the formation of the latter, based on density functional theory calculations and accompanying spectroscopic data.

Copper(II) complex of new non-innocent O-aminophenol-based ligand as biomimetic model for galactose oxidase enzyme in aerobic oxidation of alcohols

NASA Astrophysics Data System (ADS)

Safaei, Elham; Bahrami, Hadiseh; Pevec, Andrej; Kozlevčar, Bojan; Jagličić, Zvonko

2017-04-01

Mononuclear copper(II) complex of tetra-dentate o-aminophenol-based ligand (H2LBAPP) has been synthesized and characterized. The three dentate precursor (HLBAP) of the final ligand was synthesized first, while the title four-dentate copper bound ligand was synthesized in situ, isolated only in the final copper species [CuLBAPP]. This copper coordination complex reveals a distorted square-planar geometry around the copper(II) centre by one oxygen and three nitrogen atoms from the coordinating ligand. The ligand is thus twice deprotonated via hydroxy and amine groups. The complex is red, non-typical for copper(II), but the effective magnetic moment of 1.86 B M. and a single isotropic symmetry EPR signal with g 2.059 confirm a S = 1/2 diluted spin system, without copper-copper magnetic coupling. Electrochemical oxidation of this complex yields the corresponding Cu(II)-phenyl radical species. Finally, the title complex CuLBAPP has shown good and selective catalytic activity towards alcohol to aldehyde oxidation, at aerobic room temperature conditions, for a set of different alcohols.

Membrane-organized Chemical Photoredox Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Britt, R. David

2016-09-01

The key photoredox process in photosynthesis is the accumulation of oxidizing equivalents on a tetranuclear manganese cluster that then liberates electrons and protons from water and forms oxygen gas. Our primary goal in this project is to characterize inorganic systems that can perform this same water-splitting chemistry. One such species is the dinuclear ruthenium complex known as the blue dimer. Starting at the Ru(III,III) oxidation state, the blue dimer is oxidized up to a putative Ru(V,V) level prior to O-O bond formation. We employ electron paramagnetic resonance spectroscopy to characterize each step in this reaction cycle to gain insight intomore » the molecular mechanism of water oxidation.« less

COMMD1 is linked to the WASH complex and regulates endosomal trafficking of the copper transporter ATP7A

PubMed Central

Phillips-Krawczak, Christine A.; Singla, Amika; Starokadomskyy, Petro; Deng, Zhihui; Osborne, Douglas G.; Li, Haiying; Dick, Christopher J.; Gomez, Timothy S.; Koenecke, Megan; Zhang, Jin-San; Dai, Haiming; Sifuentes-Dominguez, Luis F.; Geng, Linda N.; Kaufmann, Scott H.; Hein, Marco Y.; Wallis, Mathew; McGaughran, Julie; Gecz, Jozef; van de Sluis, Bart; Billadeau, Daniel D.; Burstein, Ezra

2015-01-01

COMMD1 deficiency results in defective copper homeostasis, but the mechanism for this has remained elusive. Here we report that COMMD1 is directly linked to early endosomes through its interaction with a protein complex containing CCDC22, CCDC93, and C16orf62. This COMMD/CCDC22/CCDC93 (CCC) complex interacts with the multisubunit WASH complex, an evolutionarily conserved system, which is required for endosomal deposition of F-actin and cargo trafficking in conjunction with the retromer. Interactions between the WASH complex subunit FAM21, and the carboxyl-terminal ends of CCDC22 and CCDC93 are responsible for CCC complex recruitment to endosomes. We show that depletion of CCC complex components leads to lack of copper-dependent movement of the copper transporter ATP7A from endosomes, resulting in intracellular copper accumulation and modest alterations in copper homeostasis in humans with CCDC22 mutations. This work provides a mechanistic explanation for the role of COMMD1 in copper homeostasis and uncovers additional genes involved in the regulation of copper transporter recycling. PMID:25355947

Pyrrolidine dithiocarbamate-zinc(II) and -copper(II) complexes induce apoptosis in tumor cells by inhibiting the proteasomal activity☆

PubMed Central

Milacic, Vesna; Chen, Di; Giovagnini, Lorena; Diez, Alejandro; Fregona, Dolores; Dou, Q. Ping

2013-01-01

Zinc and copper are trace elements essential for proper folding, stabilization and catalytic activity of many metalloenzymes in living organisms. However, disturbed zinc and copper homeostasis is reported in many types of cancer. We have previously demonstrated that copper complexes induced proteasome inhibition and apoptosis in cultured human cancer cells. In the current study we hypothesized that zinc complexes could also inhibit the proteasomal chymotrypsin-like activity responsible for subsequent apoptosis induction. We first showed that zinc(II) chloride was able to inhibit the chymotrypsin-like activity of a purified 20S proteasome with an IC50 value of 13.8 μM, which was less potent than copper(II) chloride (IC50 5.3 μM). We then compared the potencies of a pyrrolidine dithiocarbamate (PyDT)-zinc(II) complex and a PyDT-copper(II) complex to inhibit cellular proteasomal activity, suppress proliferation and induce apoptosis in various human breast and prostate cancer cell lines. Consistently, zinc complex was less potent than copper complex in inhibiting the proteasome and inducing apoptosis. Additionally, zinc and copper complexes appear to use somewhat different mechanisms to kill tumor cells. Zinc complexes were able to activate calpain-, but not caspase-3-dependent pathway, while copper complexes were able to induce activation of both proteases. Furthermore, the potencies of these PyDT-metal complexes depend on the nature of metals and also on the ratio of PyDT to the metal ion within the complex, which probably affects their stability and availability for interacting with and inhibiting the proteasome in tumor cells. PMID:18501397

Syntheses, structures and characterizations of three novel vanadium selenites with organically bonded copper/nickel complex

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qian, Cheng; State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002; Kong, Fang

2016-06-15

A series of vanadium selenites covalently bonded with metal-organic complex, namely, Ni(2,2-bipy){sub 2}V{sub 2}O{sub 4}(SeO{sub 3}){sub 2} (1), Cu(2,2-bipy)V{sub 2}O{sub 4}(SeO{sub 3}){sub 2}·0.5H{sub 2}O (2) and Cu{sub 2}(2,2-bipy){sub 2}V{sub 5}O{sub 12}(SeO{sub 3}){sub 2} (3) (2,2-bipy=2,2-bipyridine) have been hydrothermally synthesized and structurally characterized. They exhibit three different structural dimensions, from 0D cluster, 1D chain to 2D layer. Compound 1 features a 0D {Ni(2,2-bipy)_2V_2O_4(SeO_3)_2}{sub 2} dimeric cluster composed of two {Ni(2,2-bipy)_2}{sup 2+} moieties connected by the {V_4O_8(SeO_3)_4}{sup 4-} cluster. Compound 2 shows a 1D {Cu(2,2-bipy)V_2O_4(SeO_3)_2}{sub n} chain in which the {Cu_2(2,2-bipy)_2}{sup 4+} moieties are bridged by the {V_4O_8(SeO_3)_4}{sup 4−} clusters. Compound 3more » displays a 2D structure consisted of mixed valence vanadium selenites layers {V"I"VV"V_4Se"I"V_2O_1_8}{sub n}{sup 4−} and {Cu(2,2-bipy)}{sup 2+} complex moieties. The adjacent layers are further interconnected via π-π interactions between the 2,2-bipy ligands exhibiting an interesting 3D supramolecular architecture. Both compound 1 and 2 contain a new {V_4O_8(SeO_3)_4}{sup 4−} cluster and compound 3 exhibits the first 2D vanadate polyhedral layer in vanadium selenites/tellurites with organic moieties. - Graphical abstract: We got three new vanadium selenites with organically linked copper/nickel complex, namely, Ni(2,2-bipy){sub 2}V{sub 2}O{sub 4}(SeO{sub 3}){sub 2} (1), Cu(2,2-bipy)V{sub 2}O{sub 4}(SeO{sub 3}){sub 2}·0.5H{sub 2}O (2) and Cu{sub 2}(2,2-bipy){sub 2}V{sub 5}O{sub 12}(SeO{sub 3}){sub 2} (3) by hydrothermally syntheses. They display three different structural dimensions, from 0D cluster, to 1D chain and 2D layer. Display Omitted - Highlights: • Three new compounds display three different structural dimensions, from 0D cluster, to 1D chain and 2D layer. • The Tetranuclear {V_4O_8(SeO_3)_4}{sup 4−} cluster and the vanadate {V_5O_1_7}{sub n} 2D layer are observed firstly. • Optical Properties and Magnetic Properties of three compounds are reported.« less

Synthesis, characterization and biological studies of copper(II) complexes with 2-aminobenzimidazole derivatives

NASA Astrophysics Data System (ADS)

Joseph, J.; Suman, A.; Nagashri, K.; Joseyphus, R. Selwin; Balakrishnan, Nisha

2017-06-01

Novel series of four copper(II) complexes with 2-aminobenzimidazole derivatives (obtained from the Knoevenagel condensate of acetylacetone (obtained from acetylacetone and halogen substituted benzaldehydes) and 2-aminobenzimidazole) were synthesized. They were structurally characterized using elemental analysis, molar conductance, FAB mass, FT- IR, 1H &13C-NMR, UV-Vis., and EPR techniques. On the basis of analytical and spectral studies, the distorted square planar geometry was assigned for all the complexes. The antibacterial screening of the ligands and their copper complexes indicated that all the complexes showed higher anti microbial activities than the free ligands. Superoxide dismutase and antioxidant activities of the copper complexes have also been performed. In the electrochemical technique, the shift in ΔEp, E1/2 and Ipc values were explored for the interaction of the complexes with CT-DNA. During the electrolysis process, the present ligand system stabilizes unusual oxidation state of copper in the complexes. It is believed that the copper complexes with curcumin analogs may enhance chemotherapeutic behavior.

Tetrametallic molecular catalysts for photochemical water oxidation.

PubMed

Sartorel, Andrea; Bonchio, Marcella; Campagna, Sebastiano; Scandola, Franco

2013-03-21

Among molecular water oxidation catalysts (WOCs), those featuring a reactive set of four multi-redox transition metals can leverage an extraordinary interplay of electronic and structural properties. These are of particular interest, owing to their close structural, and possibly functional, relationship to the oxygen evolving complex of natural photosynthesis. In this review, special attention is given to two classes of tetrametallic molecular WOCs: (i) M(4)O(4) cubane-type structures stabilized by simple organic ligands, and (ii) systems in which a tetranuclear metal core is stabilized by coordination of two polyoxometalate (POM) ligands. Recent work in this rapidly evolving field is reviewed, with particular emphasis on photocatalytic aspects. Special attention is given to studies addressing the mechanistic complexity of these systems, sometimes overlooked in the rush for oxygen evolving performance. The complementary role of molecular WOCs and their relationship with bulk oxides and heterogeneous catalysis are discussed.

Design and its limitations in the construction of bi- and poly-nuclear coordination complexes and coordination polymers (aka MOFs): a personal view.

PubMed

Robson, R

2008-10-14

This article, presented from a personal point of view, is concerned with the design of ligands intended to give specifically either binuclear or tetranuclear metal complexes or coordination polymers. No attempt is made to provide a comprehensive coverage of these topics, the focus being mainly upon results from our laboratory. Some emphasis is placed upon aspects of the historical development of the deliberate construction of coordination polymers (aka MOFs)--materials promising useful applications, the study of which continues to expand exponentially. Some of our recent research is described in which the carbonate ion and the tetracyanoquinodimethane dianion are used as bridging ligands to generate targeted coordination polymers. It is intended that Dalton Perspectives be easily comprehensible to non-specialists in the field; an average second year university chemistry student should be easily able to understand the present contribution.

DNA binding and biological studies of some novel water-soluble polymer-copper(II)-phenanthroline complexes.

PubMed

Kumar, Rajendran Senthil; Arunachalam, Sankaralingam; Periasamy, Vaiyapuri Subbarayan; Preethy, Christo Paul; Riyasdeen, Anvarbatcha; Akbarsha, Mohammad Abdulkader

2008-10-01

Some novel water-soluble polymer-copper(II)-phenanthroline complex samples, [Cu(phen)2(BPEI)]Cl(2).4H2O (phen=1,10-phenanthroline, BPEI=branched polyethyleneimine), with different degrees of copper complex content in the polymer chain have been prepared by ligand substitution method in water-ethanol medium and characterized by infrared, UV-visible, EPR spectral and elemental analysis methods. The binding of these complex samples with DNA has been investigated by electronic absorption spectroscopy, emission spectroscopy and gel retardation assay. Electrostatic interactions between DNA molecule and polymer-copper(II) complex molecule containing many high positive charges have been observed. Besides these ionic interactions, van der Waals interactions, hydrogen bonding and other partial intercalation binding modes may also exist in this system. The polymer-copper(II) complex with higher degree of copper complex content was screened for its antimicrobial activity and antitumor activity.

Characteristics of coated copper wire specimens using high frequency ultrasonic complex vibration welding equipments.

PubMed

Tsujino, J; Ihara, S; Harada, Y; Kasahara, K; Sakamaki, N

2004-04-01

Welding characteristic of thin coated copper wires were studied using 40, 60, 100 kHz ultrasonic complex vibration welding equipments with elliptical to circular vibration locus. The complex vibration systems consisted of a longitudinal-torsional vibration converter and a driving longitudinal vibration system. Polyurethane coated copper wires of 0.036 mm outer diameter and copper plates of 0.3 mm thickness and the other dimension wires were used as welding specimens. The copper wire part is completely welded on the copper substrate and the insulated coating material is driven from welded area to outsides of the wire specimens by high frequency complex vibration.

Nitric oxide activation by distal redox modulation in tetranuclear iron nitrosyl complexes.

PubMed

de Ruiter, Graham; Thompson, Niklas B; Lionetti, Davide; Agapie, Theodor

2015-11-11

A series of tetranuclear iron complexes displaying a site-differentiated metal center was synthesized. Three of the metal centers are coordinated to our previously reported ligand, based on a 1,3,5-triarylbenzene motif with nitrogen and oxygen donors. The fourth (apical) iron center is coordinatively unsaturated and appended to the trinuclear core through three bridging pyrazolates and an interstitial μ4-oxide moiety. Electrochemical studies of complex [LFe3(PhPz)3OFe][OTf]2 revealed three reversible redox events assigned to the Fe(II)4/Fe(II)3Fe(III) (-1.733 V), Fe(II)3Fe(III)/Fe(II)2Fe(III)2 (-0.727 V), and Fe(II)2Fe(III)2/Fe(II)Fe(III)3 (0.018 V) redox couples. Combined Mössbauer and crystallographic studies indicate that the change in oxidation state is exclusively localized at the triiron core, without changing the oxidation state of the apical metal center. This phenomenon is assigned to differences in the coordination environment of the two metal sites and provides a strategy for storing electron and hole equivalents without affecting the oxidation state of the coordinatively unsaturated metal. The presence of a ligand-binding site allowed the effect of redox modulation on nitric oxide activation by an Fe(II) metal center to be studied. Treatment of the clusters with nitric oxide resulted in binding of NO to the apical iron center, generating a {FeNO}(7) moiety. As with the NO-free precursors, the three reversible redox events are localized at the iron centers distal from the NO ligand. Altering the redox state of the triiron core resulted in significant change in the NO stretching frequency, by as much as 100 cm(-1). The increased activation of NO is attributed to structural changes within the clusters, in particular, those related to the interaction of the metal centers with the interstitial atom. The differences in NO activation were further shown to lead to differential reactivity, with NO disproportionation and N2O formation performed by the more electron-rich cluster.

Liquid-crystalline dendrimer Cu(II) complexes and Cu(0) nanoclusters based on the Cu(II) complexes: An electron paramagnetic resonance investigation

NASA Astrophysics Data System (ADS)

Domracheva, N. E.; Mirea, A.; Schwoerer, M.; Torre-Lorente, L.; Lattermann, G.

2007-07-01

New nanostructured materials, namely, the liquid-crystalline copper(II) complexes that contain poly(propylene imine) dendrimer ligands of the first (ligand 1) and second (ligand 2) generations and which have a columnar mesophase and different copper contents (x = Cu/L), are investigated by EPR spectroscopy. The influence of water molecules and nitrate counterions on the magnetic properties of complex 2 (x = 7.3) is studied. It is demonstrated that water molecules can extract some of the copper ions from dendrimer complexes and form hexaaqua copper complexes with free ions. The dimer spectra of fully hydrated complex 2 (x = 7.3) are observed at temperatures T < 10 K. For this complex, the structure is identified and the distance between the copper ions is determined. It is shown that the nitrate counterion plays the role of a bridge between the hexaaqua copper(II) complex and the dendrimer copper(II) complex. The temperature-induced valence tautomerism attended by electron transport is revealed for the first time in blue dendrimer complexes 1 (x = 1.9) with a dimer structure. The activation energy for electron transport is estimated to be 0.35 meV. The coordination of the copper ion site (NO4) and the structural arrangement of green complexes 1 (x = 1.9) in the columnar mesophase are determined. Complexes of this type form linear chains in which nitrate counterions serve as bridges between copper centers. It is revealed that green complexes 1 (x = 1.9) dissolved in isotropic inert solvents can be oriented in the magnetic field (B 0 = 8000 G). The degree of orientation of these complexes is rather high (S z = 0.76) and close to that of systems with a complete ordering (S z = 1) in the magnetic field. Copper(0) nanoclusters prepared by reduction of complex 2 (x = 7.3) in two reducing agents (NaBH4, N2H4 · H2O) are examined. A model is proposed for a possible location of Cu(0) nanoclusters in a dendrimer matrix.

Pyrazine as a building block for molecular architectures with PtII.

PubMed

Willermann, Michael; Mulcahy, Clodagh; Sigel, Roland K O; Cerdà, Marta Morell; Freisinger, Eva; Sanz Miguel, Pablo J; Roitzsch, Michael; Lippert, Bernhard

2006-03-06

A series of pyrazine (pz) complexes containing cis-(NH(3))(2)Pt(II), (tmeda)Pt(II) (tmeda = N,N,N',N'-tetramethylethylenediamine), and trans-(NH(3))(2)Pt(II) entities have been prepared and characterized by X-ray crystallography and/or 1H NMR spectroscopy. In these compounds, the pz ligands act as monodentate (1-3) or bidentate bridging ligands (4-7). Three variants of the latter case are described: a dinuclear complex [Pt(II)]2 (4b), a cyclic tetranuclear [Pt(II)](4) complex (5), and a trinuclear mixed-metal complex [Pt2Ag] (7). Mono- and bidentate binding modes are readily differentiated by 1H NMR spectroscopy, and the assignment of pz protons in the case of monodentate coordination is aided by the observation of (195)Pt satellites. Formation of the open molecular box cis-[{(NH3)2Pt(pz)}4](NO3)8.3.67H2O (5) from cis-(NH3)2Pt(II) and pz follows expectations of the "molecular library approach" for the generation of a cyclic tetramer.

Reactivity Study of Unsymmetrical β-Diketiminato Copper(I) Complexes: Effect of the Chelating Ring.

PubMed

Chuang, Wan-Jung; Hsu, Sung-Po; Chand, Kuldeep; Yu, Fu-Lun; Tsai, Cheng-Long; Tseng, Yu-Hsuan; Lu, Yuh-Hsiu; Kuo, Jen-Yu; Carey, James R; Chen, Hsuan-Ying; Chen, Hsing-Yin; Chiang, Michael Y; Hsu, Sodio C N

2017-03-06

β-Diketiminato copper(I) complexes play important roles in bioinspired catalytic chemistry and in applications to the materials industry. However, it has been observed that these complexes are very susceptible to disproportionation. Coordinating solvents or Lewis bases are typically used to prevent disproportionation and to block the coordination sites of the copper(I) center from further decomposition. Here, we incorporate this coordination protection directly into the molecule in order to increase the stability and reactivity of these complexes and to discover new copper(I) binding motifs. Here we describe the synthesis, structural characterization, and reactivity of a series of unsymmetrical N-aryl-N'-alkylpyridyl β-diketiminato copper(I) complexes and discuss the structures and reactivity of these complexes with respect to the length of the pyridyl arm. All of the aforementioned unsymmetrical ß-diketiminato copper(I) complexes bind CO reversibly and are stable to disproportionation. The binding ability of CO and the rate of pyridyl ligand decoordination of these copper(I) complexes are directly related to the competition between the degree of puckering of the chelate system and the steric demands of the N-aryl substituent.

Tetranuclear cluster-based Pb(II)-MOF: Synthesis, crystal structure and luminescence sensing for CS2

NASA Astrophysics Data System (ADS)

Dong, Yanli

2018-05-01

A new Pb(II) coordination polymer, namely [Pb2(bptc)(DMA)]n (1, H4bptc = biphenyl-3,3‧,5,5‧-tetracarboxylic acid, DMA = N, N‧- dimethylacetamide), has been synthesized by the combination of H4bptc with Pb(NO3)2 under solvothermal conditions. Single crystal X-ray diffraction analysis revealed that compound 1 features a 3D framework based on tetranuclear [Pb4(COO)6] subunits, and topological analysis revealed that compound represents a binodal (4, 8)-connected scu-type topological network with the point symbol of {416,612}{44,62}2. Luminescence studies indicated that 1 and 1' (1‧ represents the desolvated samples) showed intense yellow emissions. Significantly, 1‧ exhibited sensitive luminescence sensing for CS2 solvent molecules at a low concentration.

Self-reduction of a copper complex MOD ink for inkjet printing conductive patterns on plastics.

PubMed

Farraj, Yousef; Grouchko, Michael; Magdassi, Shlomo

2015-01-31

Highly conductive copper patterns on low-cost flexible substrates are obtained by inkjet printing a metal complex based ink. Upon heating the ink, the soluble complex, which is composed of copper formate and 2-amino-2-methyl-1-propanol, decomposes under nitrogen at 140 °C and is converted to pure metallic copper. The decomposition process of the complex is investigated and a suggested mechanism is presented. The ink is stable in air for prolonged periods, with no sedimentation or oxidation problems, which are usually encountered in copper nanoparticle based inks.

Determination of formal redox potentials in aqueous solution of copper(II) complexes with ligands having nitrogen and oxygen donor atoms and comparison with their EPR and UV-Vis spectral features.

PubMed

Tabbì, Giovanni; Giuffrida, Alessandro; Bonomo, Raffaele P

2013-11-01

Formal redox potentials in aqueous solution were determined for copper(II) complexes with ligands having oxygen and nitrogen as donor atoms. All the chosen copper(II) complexes have well-known stereochemistries (pseudo-octahedral, square planar, square-based pyramidal, trigonal bipyramidal or tetrahedral) as witnessed by their reported spectroscopic, EPR and UV-visible (UV-Vis) features, so that a rough correlation between the measured redox potential and the typical geometrical arrangement of the copper(II) complex could be established. Negative values have been obtained for copper(II) complexes in tetragonally elongated pseudo-octahedral geometries, when measured against Ag/AgCl reference electrode. Copper(II) complexes in tetrahedral environments (or flattened tetrahedral geometries) show positive redox potential values. There is a region, always in the field of negative redox potentials which groups the copper(II) complexes exhibiting square-based pyramidal arrangements. Therefore, it is suggested that a measurement of the formal redox potential could be of great help, when some ambiguities might appear in the interpretation of spectroscopic (EPR and UV-Vis) data. Unfortunately, when the comparison is made between copper(II) complexes in square-based pyramidal geometries and those in square planar environments (or a pseudo-octahedral) a little perturbed by an equatorial tetrahedral distortion, their redox potentials could fall in the same intermediate region. In this case spectroscopic data have to be handled with great care in order to have an answer about a copper complex geometrical characteristics. © 2013.

DNA/RNA binding and anticancer/antimicrobial activities of polymer-copper(II) complexes

NASA Astrophysics Data System (ADS)

Lakshmipraba, Jagadeesan; Arunachalam, Sankaralingam; Riyasdeen, Anvarbatcha; Dhivya, Rajakumar; Vignesh, Sivanandham; Akbarsha, Mohammad Abdulkader; James, Rathinam Arthur

2013-05-01

Water soluble polymer-copper(II) complexes with various degrees of coordination in the polymer chain were synthesized and characterized by elemental analysis, IR, UV-visible and EPR spectra. The DNA/RNA binding behavior of these polymer-copper(II) complexes was examined by UV-visible absorption, emission and circular dichroism spectroscopic methods, and cyclic voltammetry techniques. The binding of the polymer-copper(II) complexes with DNA/RNA was mainly through intercalation but some amount of electrostatic interaction was also observed. This binding capacity increased with the degree of coordination of the complexes. The polymer-copper(II) complex having the highest degree of coordination was subjected to analysis of cytotoxic and antimicrobial properties. The cytotoxicity study indicated that the polymer-copper(II) complexes affected the viability of MCF-7 mammary carcinoma cells, and the cells responded to the treatment with mostly through apoptosis although a few cells succumbed to necrosis. The antimicrobial screening showed activity against some human pathogens.

Synthetic bioactive novel ether based Schiff bases and their copper(II) complexes

NASA Astrophysics Data System (ADS)

Shabbir, Muhammad; Akhter, Zareen; Ismail, Hammad; Mirza, Bushra

2017-10-01

Novel ether based Schiff bases (HL1- HL4) were synthesized from 5-chloro-2-hydroxy benzaldehyde and primary amines (1-amino-4-phenoxybenzene, 4-(4-aminophenyloxy) biphenyl, 1-(4-aminophenoxy) naphthalene and 2-(4-aminophenoxy) naphthalene). From these Schiff bases copper(II) complexes (Cu(L1)2-Cu(L4)2)) were synthesized and characterized by elemental analysis and spectroscopic (FTIR, NMR) techniques. The synthesized Schiff bases and copper(II) complexes were further assessed for various biological studies. In brine shrimp assay the copper(II) complexes revealed 4-fold higher activity (LD50 3.8 μg/ml) as compared with simple ligands (LD50 12.4 μg/ml). Similar findings were observed in potato disc antitumor assay with higher activities for copper(II) complexes (IC50 range 20.4-24.1 μg/ml) than ligands (IC50 range 40.5-48.3 μg/ml). DPPH assay was performed to determine the antioxidant potential of the compounds. Significant antioxidant activity was shown by the copper(II) complexes whereas simple ligands have shown no activity. In DNA protection assay significant protection behavior was exhibited by simple ligand molecules while copper(II) complexes showed neutral behavior (neither protective nor damaging).

Study on the mechanism of copper-ammonia complex decomposition in struvite formation process and enhanced ammonia and copper removal.

PubMed

Peng, Cong; Chai, Liyuan; Tang, Chongjian; Min, Xiaobo; Song, Yuxia; Duan, Chengshan; Yu, Cheng

2017-01-01

Heavy metals and ammonia are difficult to remove from wastewater, as they easily combine into refractory complexes. The struvite formation method (SFM) was applied for the complex decomposition and simultaneous removal of heavy metal and ammonia. The results indicated that ammonia deprivation by SFM was the key factor leading to the decomposition of the copper-ammonia complex ion. Ammonia was separated from solution as crystalline struvite, and the copper mainly co-precipitated as copper hydroxide together with struvite. Hydrogen bonding and electrostatic attraction were considered to be the main surface interactions between struvite and copper hydroxide. Hydrogen bonding was concluded to be the key factor leading to the co-precipitation. In addition, incorporation of copper ions into the struvite crystal also occurred during the treatment process. Copyright © 2016. Published by Elsevier B.V.

Synthesis, characterization and biological activities of semicarbazones and their copper complexes.

PubMed

Venkatachalam, Taracad K; Bernhardt, Paul V; Noble, Chris J; Fletcher, Nicholas; Pierens, Gregory K; Thurecht, Kris J; Reutens, David C

2016-09-01

Substituted semicarbazones/thiosemicarbazones and their copper complexes have been prepared and several single crystal structures examined. The copper complexes of these semicarbazone/thiosemicarbazones were prepared and several crystal structures examined. The single crystal X-ray structure of the pyridyl-substituted semicarbazone showed two types of copper complexes, a monomer and a dimer. We also found that the p-nitrophenyl semicarbazone formed a conventional 'magic lantern' acetate-bridged dimer. Electron Paramagnetic Resonance (EPR) of several of the copper complexes was consistent with the results of single crystal X-ray crystallography. The EPR spectra of the p-nitrophenyl semicarbazone copper complex in dimethylsulfoxide (DMSO) showed the presence of two species, confirming the structural information. Since thiosemicarbazones and semicarbazones have been reported to exhibit anticancer activity, we examined the anticancer activity of several of the derivatives reported in the present study and interestingly only the thiosemicarbazone showed activity while the semicarbazones were not active indicating that introduction of sulphur atom alters the biological profile of these thiosemicarbazones. Copyright © 2016 Elsevier Inc. All rights reserved.

Dianionic Carbon-Bridged Scandium-Copper/Silver Heterobimetallic Complexes: Synthesis, Bonding, and Reactivity.

PubMed

Wang, Chen; Xiang, Li; Yang, Yan; Fang, Jian; Maron, Laurent; Leng, Xuebing; Chen, Yaofeng

2018-04-11

Alkylidene-bridged scandium-copper/silver heterobimetallic complexes were synthesized and structurally characterized. The complexes contain different Sc-C and M-C (M=Cu I , Ag I ) bonds. The reactivity of the scandium-copper heterobimetallic complex was also studied, which reveals that the heterobimetallic complex is a reaction intermediate for the transmetalation of akylidene group from Sc III to Cu I . The scandium-copper heterobimetallic complex also undergoes an addition reaction with CO, resulting in the formation of a new C=C double bond. DFT calculations were used to study the bonding and the subsequent reactivity with CO of the scandium-copper heterobimetallic complex. It clearly demonstrates a cooperative effect between the two metal centers through the formation of a direct Sc⋅⋅⋅Cu interaction that drives the reactivity with CO. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Towards a selective adsorbent for arsenate and selenite in the presence of phosphate: Assessment of adsorption efficiency, mechanism, and binary separation factors of the chitosan-copper complex.

PubMed

Yamani, Jamila S; Lounsbury, Amanda W; Zimmerman, Julie B

2016-01-01

The potential for a chitosan-copper polymer complex to select for the target contaminants in the presence of their respective competitive ions was evaluated by synthesizing chitosan-copper beads (CCB) for the treatment of (arsenate:phosphate), (selenite:phosphate), and (selenate:sulfate). Based on work by Rhazi et al., copper (II) binds to the amine moiety on the chitosan backbone as a monodentate complex (Type I) and as a bidentate complex crosslinking two polymer chains (Type II), depending on pH and copper loading. In general, the Type I complex exists alone; however, beyond threshold conditions of pH 5.5 during synthesis and a copper loading of 0.25 mol Cu(II)/mol chitosan monomer, the Type I and Type II complexes coexist. Subsequent chelation of this chitosan-copper ligand to oxyanions results in enhanced and selective adsorption of the target contaminants in complex matrices with high background ion concentrations. With differing affinities for arsenate, selenite, and phosphate, the Type I complex favors phosphate chelation while the Type II complex favors arsenate chelation due to electrostatic considerations and selenite chelation due to steric effects. No trend was exhibited for the selenate:sulfate system possibly due to the high Ksp of the corresponding copper salts. Binary separation factors, α12, were calculated for the arsenate-phosphate and selenite-phosphate systems, supporting the mechanistic hypothesis. While, further research is needed to develop a synthesis method for the independent formation of the Type II complexes to select for target contaminants in complex matrices, this work can provide initial steps in the development of a selective adsorbent. Copyright © 2015 Elsevier Ltd. All rights reserved.

Copper complexes as a source of redox active MRI contrast agents.

PubMed

Dunbar, Lynsey; Sowden, Rebecca J; Trotter, Katherine D; Taylor, Michelle K; Smith, David; Kennedy, Alan R; Reglinski, John; Spickett, Corinne M

2015-10-01

The study reports an advance in designing copper-based redox sensing MRI contrast agents. Although the data demonstrate that copper(II) complexes are not able to compete with lanthanoids species in terms of contrast, the redox-dependent switch between diamagnetic copper(I) and paramagnetic copper(II) yields a novel redox-sensitive contrast moiety with potential for reversibility.

Spectroscopic and molecular docking studies on the interaction of human serum albumin with copper(II) complexes

NASA Astrophysics Data System (ADS)

Guhathakurta, Bhargab; Pradhan, Ankur Bikash; Das, Suman; Bandyopadhyay, Nirmalya; Lu, Liping; Zhu, Miaoli; Naskar, Jnan Prakash

2017-02-01

Two osazone based ligands, butane-2,3-dione bis(2‧-pyridylhydrazone) (BDBPH) and hexane-3,4-dione bis(2‧-pyridylhydrazone) (HDBPH), were synthesized out of the 2:1 M Schiff base condensation of 2-hydrazino pyridine respectively with 2,3-butanedione and 3,4-hexanedione. The X-ray crystal structures of both the ligands have been determined. The copper(II) complex of HDBPH has also been synthesized and structurally characterized. HDBPH and its copper(II) complex have thoroughly been characterized through various spectroscopic and analytical techniques. The X-ray crystal structure of the copper complex of HDBPH shows that it is a monomeric Cu(II) complex having 'N4O2' co-ordination chromophore. Interaction of human serum albumin (HSA) with these ligands and their monomeric copper(II) complexes have been studied by various spectroscopic means. The experimental findings show that the ligands as well as their copper complexes are good HSA binders. Molecular docking investigations have also been done to unravel the mode of binding of the species with HSA.

21 CFR 73.1125 - Potassium sodium copper chloropyhllin (chlorophyllin-copper complex).

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Potassium sodium copper chloropyhllin (chlorophyllin-copper complex). 73.1125 Section 73.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73...

21 CFR 73.1125 - Potassium sodium copper chloropyhllin (chlorophyllin-copper complex).

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Potassium sodium copper chloropyhllin (chlorophyllin-copper complex). 73.1125 Section 73.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73...

21 CFR 73.1125 - Potassium sodium copper chloropyhllin (chlorophyllin-copper complex).

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Potassium sodium copper chloropyhllin (chlorophyllin-copper complex). 73.1125 Section 73.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73...

21 CFR 73.1125 - Potassium sodium copper chloropyhllin (chlorophyllin-copper complex).

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Potassium sodium copper chloropyhllin (chlorophyllin-copper complex). 73.1125 Section 73.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73...

21 CFR 73.2125 - Potassium sodium copper chlorophyllin (chlorophyllin-copper complex).

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). 73.2125 Section 73.2125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics...

21 CFR 73.2125 - Potassium sodium copper chlorophyllin (chlorophyllin-copper complex).

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Potassium sodium copper chlorophyllin (chlorophyllin-copper complex). 73.2125 Section 73.2125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics...

CNC Machining Of The Complex Copper Electrodes

NASA Astrophysics Data System (ADS)

Popan, Ioan Alexandru; Balc, Nicolae; Popan, Alina

2015-07-01

This paper presents the machining process of the complex copper electrodes. Machining of the complex shapes in copper is difficult because this material is soft and sticky. This research presents the main steps for processing those copper electrodes at a high dimensional accuracy and a good surface quality. Special tooling solutions are required for this machining process and optimal process parameters have been found for the accurate CNC equipment, using smart CAD/CAM software.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Xi; Wang, Shanshan; Ghiviriga, Ion

A novel synthetic method to create gold based metallo–oligomers/polymers via the combination of inorganic click (iClick) with intermolecular aurophilic interactions is demonstrated. Complexes [PEt 3Au] 4(μ-N 3C 2C 6H 5) (1) and [PPhMe 2Au] 43C 2C 6H 5) (2) and {[PEt 3Au] 4[(μ-N 3C 2) 2-9,9-dihexyl-9H-fluorene]} n (8) have been synthesized via iClick. The tetranuclear structures of 1 and 2, induced by aurophilic bonding, are confirmed in the solid state through single crystal X-ray diffraction experiments and in solution via variable temperature NMR spectroscopy. The extended 1D structure of 8 is constructed by aurophilic induced self-assembly. 1H DOSY NMR analysismore » reveals that the aurophilic bonds in 1, 2, and 8 are retained in the solution phase. The degree of polymerization within complex 8 is temperature and concentration dependent, as determined by 1H DOSY NMR. The complex 8 is a rare example of a solution stable higher ordered structure linked by aurophilic interactions.« less

Colloidal and electrochemical aspects of copper-CMP

NASA Astrophysics Data System (ADS)

Sun, Yuxia

Copper based interconnects with low dielectric constant layers are currently used to increase interconnect densities and reduce interconnect time delays in integrated circuits. The technology used to develop copper interconnects involves Chemical Mechanical Planarization (CMP) of copper films deposited on low-k layers (silica or silica based films), which is carried out using slurries containing abrasive particles. One issue using such a structure is copper contamination over dielectric layers (SiO2 film), if not reduced, this contamination will cause current leakage. In this study, the conditions conducive to copper contamination onto SiO2 films during Cu-CMP process were studied, and a post-CMP cleaning technique was discussed based on experimental results. It was found that the adsorption of copper onto a silica surface is kinetically fast (<0.5 minute). The amount of copper absorbed is pH and concentration dependent and affected by presence of H2O2, complexing agents, and copper corrosion inhibitor Benzotrazole. Based on de-sorption results, DI water alone was unable to reduce adsorbed copper to an acceptable level, especially for adsorption that takes place at a higher pH condition. The addition of complex agent, citric acid, proved effective in suppressing copper adsorption onto oxide silica during polishing or post-CMP cleaning by forming stable copper-CA complexes. Surface Complexation Modeling was used to simulate copper adsorption isotherms and predict the copper contamination levels on SiO2 surfaces. Another issue with the application of copper CMP is its environmental impact. CMP is a costly process due to its huge consumption of pure water and slurry. Additionally, Cu-CMP processing generates a waste stream containing certain amounts of copper and abrasive slurry particles. In this study, the separation technique electrocoagulation was investigated to remove both copper and abrasive slurry particles simultaneously. For effluent containing ˜40 ppm dissolved copper, it was found that ˜90% dissolved copper was removed from the waste streams through electroplating and in-situ chemical precipitation. The amount of copper removed through plating is impacted by membrane surface charge, type/amount of complexing agents, and solid content in the slurry suspension. The slurry particles can be removed ˜90% within 2 hours of EC through multiple mechanisms.

Effect of substituent of terpyridines on the in vitro antioxidant, antitubercular, biocidal and fluorescence studies of copper(II) complexes with clioquinol

NASA Astrophysics Data System (ADS)

Kharadi, G. J.

2014-01-01

An octahedral complexes of copper with clioquinol(CQ) and substituted terpyridine have been synthesized. The Cu(II) complexes have been characterized by elemental analyses, thermogravimetric analyses, magnetic moment measurements, FT-IR, electronic, 1H NMR and FAB mass spectra. Antimycobacterial screening of ligand and its copper compound against Mycobacterium tuberculosis shows clear enhancement in the antitubercular activity upon copper complexation. Ferric-reducing anti-oxidant power of all complexes were measured. The fluorescence spectra of complexes show red shift, which may be due to the chelation by the ligands to the metal ion. It enhances ligand ability to accept electrons and decreases the electron transition energy. The antimicrobial efficiency of the complexes were tested on five different microorganisms and showed good biological activity.

Identifying Marine Copper-Binding Ligands in Seawater

NASA Astrophysics Data System (ADS)

Whitby, H.; Hollibaugh, J. T.; Maldonado, M. T.; Ouchi, S.; van den Berg, S. M.

2016-02-01

Complexation reactions are important because they affect the bioavailability of trace metals such as copper and iron. For example, organic complexation can determine whether copper is a limiting or a toxic micronutrient at natural levels. Copper competes with iron for complexing ligands, and when iron is limiting, copper can also substitute for iron in some metabolic pathways. The speciation of copper can be measured using complexing capacity titrations, which provide the concentration of individual ligand classes (L1, L2 etc.) and the complex stabilities (log K). Using methods recently developed in our laboratory, we show that the ligands within these classes can be measured independently of titrations, thus confirming the titration method and simultaneously identifying the ligands within each class. Thiols were identified as the L1 ligand class and humic compounds as the weaker L2 class in samples from coastal Georgia, USA, collected monthly from April to December. Log K values of the ligand complexes were consistent with values expected for thiols and humic substances. Recent results from culture studies and from samples collected along Line P, a coastal - oceanic transect in the HNLC region of the NE subarctic Pacific, will be presented in comparison to the estuarine results. This comparison will help to broaden our perspective on copper complexation and the ligands responsible, furthering our understanding of ligand sources and life cycles.

Copper (II) complexes of bidentate ligands exhibit potent anti-cancer activity regardless of platinum sensitivity status.

PubMed

Wehbe, Mohamed; Lo, Cody; Leung, Ada W Y; Dragowska, Wieslawa H; Ryan, Gemma M; Bally, Marcel B

2017-12-01

Insensitivity to platinum, either through inherent or acquired resistance, is a major clinical problem in the treatment of many solid tumors. Here, we explored the therapeutic potential of diethyldithiocarbamate (DDC), pyrithione (Pyr), plumbagin (Plum), 8-hydroxyquinoline (8-HQ), clioquinol (CQ) copper complexes in a panel of cancer cell lines that differ in their sensitivity to platins (cisplatin/carboplatin) using a high-content imaging system. Our data suggest that the copper complexes were effective against both platinum sensitive (IC 50  ~ 1 μM platinum) and insensitive (IC 50  > 5 μM platinum) cell lines. Furthermore, copper complexes of DDC, Pyr and 8-HQ had greater therapeutic activity compared to the copper-free ligands in all cell lines; whereas the copper-dependent activities of Plum and CQ were cell-line specific. Four of the copper complexes (Cu(DDC) 2 , Cu(Pyr) 2 , Cu(Plum) 2 and Cu(8-HQ) 2 ) showed IC 50 values less than that of cisplatin in all tested cell lines. The complex copper DDC (Cu(DDC) 2 ) was selected for in vivo evaluation due to its low nano-molar range activity in vitro and the availability of an injectable liposomal formulation. Liposomal (Cu(DDC) 2 ) was tested in a fast-growing platinum-resistant A2780-CP ovarian xenograft model and was found to achieve a statistically significant reduction (50%; p < 0.05) in tumour size. This work supports the potential use of copper-based therapeutics to treat cancers that are insensitive to platinum drugs.

Antibacterial, antibiofilm and antioxidant screening of copper(II)-complexes with some S-alkyl derivatives of thiosalicylic acid. Crystal structure of the binuclear copper(II)-complex with S-propyl derivative of thiosalicylic acid

NASA Astrophysics Data System (ADS)

Bukonjić, Andriana M.; Tomović, Dušan Lj.; Nikolić, Miloš V.; Mijajlović, Marina Ž.; Jevtić, Verica V.; Ratković, Zoran R.; Novaković, Slađana B.; Bogdanović, Goran A.; Radojević, Ivana D.; Maksimović, Jovana Z.; Vasić, Sava M.; Čomić, Ljiljana R.; Trifunović, Srećko R.; Radić, Gordana P.

2017-01-01

The spectroscopically predicted structure of the obtained copper(II)-complex with S-propyl derivative of thiosalicylic acid was confirmed by X-ray structural study. The binuclear copper(II)-complex with S-propyl derivative of thiosalicylic acid crystallized in two polymorphic forms with main structural difference in the orientation of phenyl rings relative to corresponding carboxylate groups. The antibacterial activity was tested determining the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) by using microdilution method. The influence on bacterial biofilm formation was determined by tissue culture plate method. In general, the copper(II)-complexes manifested a selective and moderate activity. The most sensitive bacteria to the effects of Cu(II)-complexes was a clinical isolate of Pseudomonas aeruginosa. For this bacteria MIC and biofilm inhibitory concentration (BIC) values for all tested complexes were in the range or better than the positive control, doxycycline. Also, for the established biofilm of clinical isolate Staphylococcus aureus, BIC values for the copper(II)-complex with S-ethyl derivative of thiosalicylic acid,[Cu2(S-et-thiosal)4(H2O)2] (C3) and copper(II)-complex with S-butyl derivative of thiosalicylic acid, [Cu2(S-bu-thiosal)4(H2O)2] (C5) were in range or better than the positive control. All the complexes acted better against Gram-positive bacteria (Staphylococcus aureus and Staphylococcus aureus ATCC 25923) than Gram-negative bacteria (Proteus mirabilis ATCC 12453, Pseudomonas aeruginosa, and P. aeruginosa ATCC 27855). The complexes showed weak antioxidative properties tested by two methods (1,1-diphenyl-2-picrylhydrazyl (DPPH) and reducing power assay).

The Copper-nicotinamide complex: sustainable applications in coupling and cycloaddition reactions

EPA Science Inventory

Crystalline copper (II)-nicotinamide complex, synthesized via simple mixing of copper chloride and nicotinamide solution at room temperature, catalyzes the C-S, C-N bond forming and cycloaddition reactions under a variety of sustainable reaction conditions.

Neurokinin B and serum albumin limit copper binding to mammalian gonadotropin releasing hormone.

PubMed

Gul, Ahmad Samir; Tran, Kevin K; Jones, Christopher E

2018-02-26

Gonadotropin releasing hormone (GnRH) triggers secretion of luteinizing hormone and follicle stimulating hormone from gonadotropic cells in the anterior pituitary gland. GnRH is able to bind copper, and both in vitro and in vivo studies have suggested that the copper-GnRH complex is more potent at triggering gonadotropin release than GnRH alone. However, it remains unclear whether copper-GnRH is the active species in vivo. To explore this we have estimated the GnRH-copper affinity and have examined whether GnRH remains copper-bound in the presence of serum albumin and the neuropeptide neurokinin B, both copper-binding proteins that GnRH will encounter in vivo. We show that GnRH has a copper dissociation constant of ∼0.9 × 10 -9  M, however serum albumin and neurokinin B can extract metal from the copper-GnRH complex. It is therefore unlikely that a copper-GnRH complex will survive transit through the pituitary portal circulation and that any effect of copper must occur outside the bloodstream in the absence of neurokinin B. Copyright © 2018 Elsevier Inc. All rights reserved.

[Influence of the earthworm Lumbricus terrestris on soil solution complexation capacity].

PubMed

el Gharmali, A; Rada, A; el Meray, M; Nejmeddine, A

2001-04-01

Four soil samples highly contaminated with metals of urban and mine origin (SE1, SE2, SM1, SM2) and having different physico-chemical proprieties were selected to study copper complexation capacity (LT) of soil solution. The effect of Lumbricus terrestris on copper complexation capacity of soil solution was investigated on SE1 and SE2. The complexation capacity was estimated by amperometric titration of soil solution by copper. Free hydrated cation and labile complexes of copper were determined by DPASV. The results show that the copper complexation capacity variation depends on the physico-chemical characteristics of soils, particularly pH. Thus, the values of copper complexation capacity are 0; 0.6 x 10(-7); 1.8 x 10(-7) and 5.5 x 10(-7) mol l-1 respectively for SM2; SM1; SE1 and SE2 which are pH 5; 5.4; 6.5 and 7.4. Based on these results, the bioavailability levels of heavy metals show the following pool ranking: SM2 > SM1 > SE1 > SE2. The copper complexation capacity of soil solution increases with the soil disturbance by Lumbricus terrestris. This is more obvious when the time of disturbance by lumbrics is longer. Indeed, average values determined for 1 month and 3 months are 3.8 x 10(-7) and 7.8 x 10(-7) mol l-1 for SE1; 7.7 x 10(-7) and 15.2 x 10(-7) mol l-1 for SE2 respectively. It seems that the action of earthworm on soil can contribute to the decrease of bioavailability of heavy metals, particularly copper.

Distinctive EPR signals provide an understanding of the affinity of bis-(3-hydroxy-4-pyridinonato) copper(II) complexes for hydrophobic environments.

PubMed

Rangel, Maria; Leite, Andreia; Silva, André M N; Moniz, Tânia; Nunes, Ana; Amorim, M João; Queirós, Carla; Cunha-Silva, Luís; Gameiro, Paula; Burgess, John

2014-07-07

In this work we report the synthesis and characterization of a set of 3-hydroxy-4-pyridinone copper(ii) complexes with variable lipophilicity. EPR spectroscopy was used to characterize the structure of copper(ii) complexes in solution, and as a tool to gain insight into solvent interactions. EPR spectra of solutions of the [CuL2] complexes recorded in different solvents reveal the presence of two copper species whose ratio depends on the nature of the solvent. Investigation of EPR spectra in the pure solvents methanol, dimethylsulfoxide, dichloromethane and their 50% (v/v) mixtures with toluene allowed the characterization of two types of copper signals (gzz = 2.30 and gzz = 2.26) whose spin-Hamiltonian parameters are consistent with solvated and non-solvated square-planar copper(ii) complexes. Regarding the potential biological application of ligands and complexes and to get insight into the partition properties in water-membrane interfaces, EPR spectra were also obtained in water-saturated octanol, an aqueous solution buffered at pH = 7.4 and liposome suspensions, for three compounds representative of different hydro-lipophilic balances. Analysis of the EPR spectra obtained in liposomes allowed establishment of the location of the complexes in the water and lipid phases. In view of the results of this work we put forward the use of EPR spectroscopy to assess the affinity of copper(ii) complexes for a hydrophobic environment and also to obtain indirect information about the lipophilicity of the ligands and similar EPR silent complexes.

Discrete Cu(i) complexes for azide-alkyne annulations of small molecules inside mammalian cells.

PubMed

Miguel-Ávila, Joan; Tomás-Gamasa, María; Olmos, Andrea; Pérez, Pedro J; Mascareñas, José L

2018-02-21

The archetype reaction of "click" chemistry, namely, the copper-promoted azide-alkyne cycloaddition (CuAAC), has found an impressive number of applications in biological chemistry. However, methods for promoting intermolecular annulations of exogenous, small azides and alkynes in the complex interior of mammalian cells, are essentially unknown. Herein we demonstrate that isolated, well-defined copper(i)-tris(triazolyl) complexes featuring designed ligands can readily enter mammalian cells and promote intracellular CuAAC annulations of small, freely diffusible molecules. In addition to simplifying protocols and avoiding the addition of "non-innocent" reductants, the use of these premade copper complexes leads to more efficient processes than with the alternative, in situ made copper species prepared from Cu(ii) sources, tris(triazole) ligands and sodium ascorbate. Under the reaction conditions, the well-defined copper complexes exhibit very good cell penetration properties, and do not present significant toxicities.

Novel metal based anti-tuberculosis agent: synthesis, characterization, catalytic and pharmacological activities of copper complexes.

PubMed

Joseph, J; Nagashri, K; Janaki, G Boomadevi

2012-03-01

Copper complexes of molecular formulae, [CuL(1)(OAc)], [CuL(2)(H(2)O)], [CuL(3)(H(2)O)], [CuL(4)(H(2)O)], [CuL(5)(H(2)O)] where L(1)-L(5) represents Schiff base ligands [by the condensation of 3-hydroxyflavone with 4-aminoantipyrine (L(1))/o-aminophenol (L(2))/o-aminobenzoic acid (L(3))/o-aminothiazole (L(4))/thiosemicarbazide (L(5))], have been prepared. They were characterized using analytical and spectral techniques. The DNA binding properties of copper complexes were studied using electronic absorption spectra and viscosity measurements. Superoxide dismutase and antioxidant activities of the copper complexes have also been studied. Furthermore, the copper complexes have been found to promote pUC18 DNA cleavage in the presence of oxidant. Anti-tuberculosis activity was also performed. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Thiolate-bridged dinuclear iron(tris-carbonyl)–nickel complexes relevant to the active site of [NiFe] hydrogenase

PubMed Central

Ohki, Yasuhiro; Yasumura, Kazunari; Kuge, Katsuaki; Tanino, Soichiro; Ando, Masaru; Li, Zilong; Tatsumi, Kazuyuki

2008-01-01

The reaction of NiBr2(EtOH)4 with a 1:2–3 mixture of FeBr2(CO)4 and Na(SPh) generated a linear trinuclear Fe–Ni–Fe cluster (CO)3Fe(μ-SPh)3Ni(μ-SPh)3Fe(CO)3, 1, whereas the analogous reaction system FeBr2(CO)4/Na(StBu)/NiBr2(EtOH)4 (1:2–3:1) gave rise to a linear tetranuclear Fe–Ni–Ni–Fe cluster [(CO)3Fe(μ-StBu)3Ni(μ-Br)]2, 2. By using this tetranuclear cluster 2 as the precursor, we have developed a new synthetic route to a series of thiolate-bridged dinuclear Fe(CO)3–Ni complexes, the structures of which mimic [NiFe] hydrogenase active sites. The reactions of 2 with SC(NMe2)2 (tmtu), Na{S(CH2)2SMe} and ortho-NaS(C6H4)SR (R = Me, tBu) led to isolation of (CO)3Fe(μ-StBu)3NiBr(tmtu), 3, (CO)3Fe(StBu)(μ-StBu)2Ni{S(CH2)2SMe}, 4, and (CO)3Fe(StBu)(μ-StBu)2Ni{S(C6H4)SR}, 5a (R = Me) and 5b (R = tBu), respectively. On the other hand, treatment of 2 with 2-methylthio-phenolate (ortho-O(C6H4)SMe) in methanol resulted in (CO)3Fe(μ-StBu)3Ni(MeOH){O(C6H4)SMe}, 6a. The methanol molecule bound to Ni is labile and is readily released under reduced pressure to afford (CO)3Fe(StBu)(μ-StBu)2Ni{O(C6H4)SMe}, 6b, and the coordination geometry of nickel changes from octahedral to square planar. Likewise, the reaction of 2 with NaOAc in methanol followed by crystallization from THF gave (CO)3Fe(μ-StBu)3Ni(THF)(OAc), 7. The dinuclear complexes, 3-7, are thermally unstable, and a key to their successful isolation is to carry out the reactions and manipulations at −40°C. PMID:18511566

The role of amine ligands in governing film morphology and electrical properties of copper films derived from copper formate-based molecular inks.

PubMed

Paquet, Chantal; Lacelle, Thomas; Liu, Xiangyang; Deore, Bhavana; Kell, Arnold J; Lafrenière, Sylvie; Malenfant, Patrick R L

2018-04-19

Copper formate complexes with various primary amines, secondary amines and pyridines were prepared, and their decomposition into conductive films was characterized. A comparison of the various complexes reveals that the temperature of thermolysis depends on the number of hydrogen bonds that can be formed between the amine and formate ligands. The particle size resulting from sintering of the copper complexes is shown to depend on the fraction of amine ligand released during the thermolysis reaction. The particle size in turn is shown to govern the electrical properties of the copper films. Correlations between the properties of the amines, such as boiling point and coordination strength, with the morphology and electrical performance of the copper films were established and provide a basis for the molecular design of copper formate molecular inks.

Spontaneous resolution of binary copper(II) complexes with racemic dipeptides: crystal structures of glycyl-L-alpha-amino-n-butyrato copper(II) monohydrate, glycyl-D-valinato copper(II) hemihydrate, and glycyl-L-valinato copper(II) hemihydrate.

PubMed

Inomata, Yoshie; Yamaguchi, Takeshi; Tomita, Airi; Yamada, Dai; Howell, F Scott

2005-08-01

Copper(II) complexes with glycyl-DL-alpha-amino-n-butyric acid (H2gly-DL-but), glycyl-DL-valine (H2gly-DL-val), glycyl-DL-norleucine (H2gly-DL-norleu), glycyl-DL-threonine (H2gly-DL-thr), glycyl-DL-serine (H2gly-DL-ser), glycyl-DL-phenylalanine (H2gly-DL-phe), and glycyl-L-valine (H2gly-L-val), have been prepared and characterized by IR, powder diffuse reflection, CD and ORD spectra, and magnetic susceptibility measurements, and by single-crystal X-ray diffraction. The crystal structures of the copper complex with H2gly-DL-but, the copper complex with H2gly-DL-val, and [Cu(gly-L-val)]n.0.5nH2O have been determined by a single-crystal X-ray diffraction method. As for the structure of the copper complex with H2gly-DL-but, the configuration around the asymmetric carbon atom is similar to that of [Cu(gly-L-val)]n.0.5nH2O. Therefore it is concluded that the copper complex with H2gly-DL-but is [Cu(gly-L-but)]n.nH2O. On the contrary, as for the structure of the copper complex with H2gly-DL-val, the configuration around the asymmetric carbon atom is different from that of [Cu(gly-L-val)]n.0.5nH2O. Therefore it is concluded that the copper complex with H2gly-dl-val is [Cu(gly-D-val)]n.0.5nH2O. So during the crystallization of the copper(II) complexes with H2gly-DL-but and H2gly-DL-val, spontaneous resolution has been observed; the four complexes have separated as [Cu(gly-D-but)]n.nH2O, [Cu(gly-L-but)]n.nH2O, [Cu(gly-D-val)]n.0.5nH2O, and [Cu(gly-L-val)]n.0.5nH2O, respectively. [Cu(gly-L-but)]n.nH2O is orthorhombic with the space group P2(1)2(1)2(1). [Cu(gly-D-val)]n.0.5nH2O and [Cu(gly-L-val)]n.0.5nH2O are monoclinic with the space group C2. In these complexes, the copper atom is in a square-pyramidal geometry, ligated by a peptide nitrogen atom, an amino nitrogen atom, a carboxyl oxygen atom, and a carboxyl oxygen atom and a peptide oxygen atom from neighboring molecules. So these complexes consist of a two-dimensional polymer chain bridged by a carboxyl oxygen atom and a peptide oxygen atom from neighboring molecules. The axial oxygen atom is located above the basal plane and the side chain of an amino acid is located below it. These polymer chains consist of only one or the other type of optical isomers; no racemic dipeptides are found. Therefore, spontaneous resolution has been observed in the crystallization of copper(II) complexes with H2gly-DL-but and H2gly-DL-val. The crystal structure of [Cu(gly-D-val)]n.0.5nH2O agrees almost completely with that of [Cu(gly-L-val)]n.0.5nH2O, except for the configuration around the asymmetric carbon atom.

The coordination structure of the extracted copper(II) complex with a synergistic mixture containing dinonylnaphthalene sulfonic acid and n-hexyl 3-pyridinecarboxylate ester

NASA Astrophysics Data System (ADS)

Zhu, Shan; Hu, Huiping; Hu, Jiugang; Li, Jiyuan; Hu, Fang; Wang, Yongxi

2017-09-01

In continuation of our interest in the coordination structure of the nickel(II) complex with dinonylnaphthalene sulfonic acid (HDNNS) and 2-ethylhexyl 4-pyridinecarboxylate ester (4PC), it was observed that the coordination sphere was completed by the coordination of two N atoms of pyridine rings in ligands 4PC and four water molecules while no direct interaction between Ni(II) and deprotonated HDNNS was observed. To investigate whether the coordination structure of nickel(II) with the synergistic mixture containing HDNNS and 4PC predominates or not in the copper(II) complex with the synergistic mixtures containing HDNNS and pyridinecarboxylate esters, a copper(II) synergist complex with n-hexyl 3-pyridinecarboxylate ester (L) and naphthalene-2-sulfonic acid (HNS, the short chain analogue of HDNNS), was prepared and studied by X-ray single crystal diffraction, elemental analyses and thermo gravimetric analysis (TGA), respectively. It was shown that the composition of the copper(II) synergist complex was [Cu(H2O)2(L)2(NS)2] and formed a trans-form distorted octahedral coordination structure. Two oxygen atoms of the two coordinated water molecules and two N atoms of the pyridine rings in the ligands L defined the basal plane while two O atoms from two sulfonate anions of the deprotonated HNS ligands occupied the apical positions by direct coordination with Cu(II), which was distinguished from the coordination structure of the nickel(II) synergist complex as reported in our previous work. In the crystal lattice, neighboring molecules [Cu(H2O)2L2(NS)2] were linked through the intermolecular hydrogen bonds between the hydrogen atoms of the coordinated water molecules and the oxygen atoms of the sulfonate anions in the copper(II) synergist complex to form a 2D plane. In order to bridge the gap between the solid state structure of the copper(II) synergist complex and the solution structure of the extracted copper(II) complex with the actual synergistic mixture containing L and HDNNS in the non-polar organic phase, the structures of the two copper(II) complexes were further investigated by Fourier transform infrared spectroscopy (FT-IR) and electrospray ionization mass spectrometry (ESI-MS), and the results indicated that the extracted copper(II) complex in the non-polar organic phase might possess a similar coordination structure as the copper(II) synergist complex.

Factors affecting catalysis of copper corrosion products in NDMA formation from DMA in simulated premise plumbing.

PubMed

Zhang, Hong; Andrews, Susan A

2013-11-01

This study investigated the effects of corrosion products of copper, a metal commonly employed in household plumbing systems, on N-nitrosodimethylamine (NDMA) formation from a known NDMA precursor, dimethylamine (DMA). Copper-catalyzed NDMA formation increased with increasing copper concentrations, DMA concentrations, alkalinity and hardness, but decreased with increasing natural organic matter (NOM) concentration. pH influenced the speciation of chloramine and the interactions of copper with DMA. The transformation of monochloramine (NH2Cl) to dichloramine and complexation of copper with DMA were involved in elevating the formation of NDMA by copper at pH 7.0. The inhibiting effect of NOM on copper catalysis was attributed to the rapid consumption of NH2Cl by NOM and/or the competitive complexation of NOM with copper to limit the formation of DMA-copper complexes. Hardness ions, as represented by Ca(2+), also competed with copper for binding sites on NOM, thereby weakening the inhibitory effect of NOM on NDMA formation. Common copper corrosion products also participated in these reactions but in different ways. Aqueous copper released from malachite [Cu2CO3(OH)2] was shown to promote NDMA formation while NDMA formation decreased in the presence of CuO, most likely due to the adsorption of DMA. Copyright © 2013 Elsevier Ltd. All rights reserved.

Heterometallic molecular precursors for a lithium-iron oxide material: synthesis, solid state structure, solution and gas-phase behaviour, and thermal decomposition.

PubMed

Han, Haixiang; Wei, Zheng; Barry, Matthew C; Filatov, Alexander S; Dikarev, Evgeny V

2017-05-02

Three heterometallic single-source precursors with a Li : Fe = 1 : 1 ratio for a LiFeO 2 oxide material are reported. Heterometallic compounds LiFeL 3 (L = tbaoac (1), ptac (2), and acac(3)) have been obtained on a large scale, in nearly quantitative yields by one-step reactions that employ readily available reagents. The heterometallic precursor LiFe(acac) 3 (3) with small, symmetric substituents on the ligand (acac = pentane-2,4-dionate), maintains a 1D polymeric structure in the solid state that limits its volatility and prevents solubility in non-coordinating solvents. The application of the unsymmetrical ligands, tbaoac (tert-butyl acetoacetate) and ptac (1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedionate), that exhibit different bridging properties at the two ends of the ligand, allowed us to change the connectivity pattern within the heterometallic assembly. The latter was demonstrated by structural characterization of heterometallic complexes LiFe(tbaoac) 3 (1) and LiFe(ptac) 3 (2) that consist of discrete heterocyclic tetranuclear molecules Li 2 Fe 2 L 6 . The compounds are highly volatile and exhibit a congruent sublimation character. DART mass spectrometric investigation revealed the presence of heterometallic molecules in the gas phase. The positive mode spectra are dominated by the presence of [M - L] + peaks (M = Li 2 Fe 2 L 6 ). In accord with their discrete molecular structure, complexes 1 and 2 are highly soluble in nearly all common solvents. In order to test the retention of the heterometallic structure in solution, the diamagnetic analog of 1, LiMg(tbaoac) 3 (4), has been isolated. Its tetranuclear molecular structure was found to be isomorphous to that of the iron counterpart. 1 H and 7 Li NMR spectroscopy unambiguously confirmed the presence of heterometallic molecules in solutions of non-coordinating solvents. The heterometallic precursor 1 was shown to exhibit clean thermal decomposition in air that results in phase-pure α-modification of layered oxide LiFeO 2 , the prospective cathode material for lithium ion batteries.

Reactions of the linear tetranuclear complex Ru sub 4 (CO) sub 10 (CH sub 3 C double bond C(H)C(H) double bond N-i-Pr) sub 2 with oxidizing reagents. Syntheses of halide-bridged (Ru(CO) sub 2 X(CH sub 3 C double bond C(H)C(H) double bond N-i-Pr)) sub 2 and fac-Ru(CO) sub 3 X(CH sub 3 C double bond C(H)C(H) double bond N-i-Pr)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mul, W.P.; Elsevier, C.J.; van Leijen, M.

1991-01-01

The linear tetranuclear complex Ru{sub 4}(CO){sub 10}(CH{sub 3}C{double bond}C(H)C(H){double bond}N-i-Pr){sub 2} (1), containing two {eta}{sup 5}-azaruthenacyclopentadienyl systems, reacts with oxidizing reagents (I{sub 2}, Br{sub 2}, NBS, CCl{sub 4}) at elevated temperatures (40-90C) in heptane or benzene to give the new dimeric halide-bridged organoruthenium(II) complexes (Ru(CO){sub 2}X(CH{sub 3}C{double bond}C(H)C(H){double bond}N-i-Pr)){sub 2} (X = I (3a), X = Br (3b), Cl (3c); yield 30-80%) together with (Ru(CO){sub 3}X{sub 2}){sub 2}. The reactions of 1 with CX{sub 4} (X = I, Br, Cl) are accelerated by CO, probably because Ru{sub 4}(CO){sub 12}(CH{sub 3}C{double bond}C(H)C(H){double bond}N-i-Pr){sub 2} (5), which contains two unbridged metal-metal bonds,more » is formed prior to oxidation. The halide-bridged dimers 3a-c are obtained as mixtures of four isomers, the configurations of which are discussed. Splitting of the halide bridges takes place when a solution of 3a-c is saturated with CO, whereby mononuclear fac-Ru(CO){sub 3}X(CH{sub 3}C{double bond}C(H)C(H){double bond}N-i-Pr) (4a-c) is obtained. This process is reversible; ie., passing a stream of nitrogen through a solution of 4a-c or removal of the solvent under vacuum causes the reverse reaction with reformation of 3a-c. Compounds 3a-c and 4a-c have been characterized by IR (3, 4), FD mass (3), {sup 1}H (3, 4), and {sup 13}C{l brace}H{r brace} NMR (4) spectroscopy and satisfactory elemental analyses have been obtained for 3a-c. Compounds 3 and 4 are suitable precursors for the preparation of new homo- and heteronuclear transition-metal complexes.« less

Structures of nitrato-(2-hydroxybenzaldehydo) (2,2 Prime -bipyridyl)copper and nitrato-(2-hydroxy-5-nitrobenzaldehydo)(2,2 Prime -bipyridyl)copper

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chumakov, Yu. M.; Paladi, L. G.; Antosyak, B. Ya.

2011-03-15

Nitrato-(2-hydroxy-5-nitrobenzaldehydo)(2,2 Prime -bipyridyl)copper (I) and nitrato-(2-hydroxybenzaldehydo)(2,2 Prime -bipyridyl)copper (II) were synthesized and characterized by X-ray diffraction. The coordination polyhedron of the central copper atom in complex I can be described as a distorted tetragonal pyramid whose base is formed by the phenol and carbonyl oxygen atoms of the monodeprotonated 2-hydroxy-5nitrobenzaldehyde molecule and the nitrogen atoms of the 2,2 Prime -bipyridyl ligand and whose apex is occupied by the oxygen atom of the nitrato group. In the crystal structure, complexes I are linked by the acido ligands and the NO{sub 2} groups of the aldehyde molecule into infinite chains. In complexmore » II, the central copper atom is coordinated by 2-hydroxybenzaldehyde, 2,2 Prime -bipyridyl, and the nitrato group, resulting in the formation of centrosymmetric dimers. The coordination polyhedron of the central copper atom can be described as a bipyramid (4 + 1 + 1) with the same base as in complex I. The axial vertices of the bipyramid are occupied by the oxygen atom of the nitrato group and the bridging phenol oxygen atom of the adjacent complex related to the initial complex by a center of symmetry. In the crystal structure, complexes II are hydrogen bonded into infinite chains.« less

40 CFR 180.1021 - Copper; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2010 CFR

2010-07-01

.... (2) Basic copper carbonate (malachite) as an algicide or herbicide in impounded and stagnant bodies.... Basic copper carbonate (malachite) 1184-64-1 Copper ammonia complex 16828-95-8 Copper ethylenediamine...

Stress Corrosion Cracking Control Plans. 3. Copper Alloys

DTIC Science & Technology

1975-06-01

convenience intended to include amines and all other species which can react with copper to produce the cupric -ammonium complex ion or perhap...capability of forming complexes even resembling the cupric -ammonium complex should be considered as potentially causative of SCC as ammonia unless...nitrate, acetate, tartrate , or citrate which also contain copper ions. There is some evidence that oxides of nitrogen (generating ammoniacal species

Time-dependent morphological and biochemical changes following cutaneous thermal burn injury and their modulation by copper nicotinate complex: an animal model.

PubMed

Nassar, Muammar A Y; Eldien, Heba M Saad; Tawab, Hanem S Abdel; Saleem, Tahia H; Omar, Hossam M; Nassar, Ahmed Y; Hussein, Mahmoud Rezk Abdelwahed

2012-10-01

Thermal tissue injury is partly mediated by reactive oxygen metabolites. Oxygen free radicals are contributory to local tissue damage following thermal injury and accordingly an interventional therapy using antioxidants may be beneficial. Copper nicotinate complex can scavenge reactive oxygen species (i.e., has antioxidant activity). To examine time-related morphological and biochemical changes following skin thermal injury and their modulation by copper nicotinate complex. An animal model composed of 80 albino rats was established. Ten rats (nonburn group) served as a control group. Seventy rats (burn group) were anesthetized, given a 10% total body surface area, full-thickness burn. Ten rats (from the postburn group) were sacrificed after 24 h (without treatment, i.e., untreated-burn group). The remaining rats were divided into three subgroups (20 rats, each) and were treated topically either with soft paraffin, moist exposed burn ointment (MEBO, a standard therapeutic treatment for burns), or copper nicotinate complex. Five animals from each subgroup were sacrificed every week over a period of 4 weeks. The morphological and biochemical changes were evaluated and compared among the different groups. High levels of the plasma and skin nitiric oxide (marker of oxidative stress) were observed in the untreated-burn group. These levels were significantly low following the application of copper nicotinate complex. Low levels of plasma and skin superoxide dismutase (marker of oxidative stress) and plasma ceruloplasmin were observed in the untreated-burn group. These levels were significantly high following copper nicotinate complex treatment. The total and differential leukocyte counts were low following the onset of the thermal injury. They gradually returned to normal levels over a 4-week period following the application of MEBO or copper nicotinate complex. Compared to untreated-burn group, postburn-healing changes (resolution of the inflammatory reaction, reepithelization of the epidermis, angiogenesis, deposition of collagen fibers, and recovery of the subcellualr organelles) were significantly accelerated following the application of either MEBO or copper nicotinate complex. Application of copper nicotinate complex was associated with improved healing of the thermal burns of the skin. The underlying molecular changes underlying these effects await further investigations.

Integrated copper-containing wastewater treatment using xanthate process.

PubMed

Chang, Yi-Kuo; Chang, Juu-En; Lin, Tzong-Tzeng; Hsu, Yu-Ming

2002-09-02

Although, the xanthate process has been shown to be an effective method for heavy metal removal from contaminated water, a heavy metal contaminated residual sludge is produced by the treatment process and the metal-xanthate sludge must be handled in accordance with the Taiwan EPA's waste disposal requirements. This work employed potassium ethyl xanthate (KEX) to remove copper ions from wastewater. The toxicity characteristic leaching procedure (TCLP) and semi-dynamic leaching test (SDLT) were used to determine the leaching potential and stability characteristics of the residual copper xanthate (Cu-EX) complexes. Results from metal removal experiments showed that KEX was suitable for the treatment of copper-containing wastewater over a wide copper concentration range (50, 100, 500, and 1000 mg/l) to the level that meets the Taiwan EPA's effluent regulations (3mg/l). The TCLP results of the residual Cu-EX complexes could meet the current regulations and thus the Cu-EX complexes could be treated as a non-hazardous material. Besides, the results of SDLT indicated that the complexes exhibited an excellent performance for stabilizing metals under acidic conditions, even slight chemical changes of the complexes occurred during extraction. The xanthate process, mixing KEX with copper-bearing solution to form Cu-EX precipitates, offered a comprehensive strategy for solving both copper-containing wastewater problems and subsequent sludge disposal requirements.

Forms of adsorption and transition states of oxidation of carbon monoxide by molecular oxygen and dissociation of nitrogen monooxide, catalyzed by monovalent copper

NASA Astrophysics Data System (ADS)

Ermakov, A. I.; Mashutin, V. Y.; Vishnjakov, A. V.

With the help of the results of semiempirical (parametric method 3) and ab initio (second-order Møller-Plesset [MP2] unrestricted Hartree-Fock [UHF] 6-31G**, unrestricted density functional theory [UDFT] 6-31G** Becke's three-parameter exchange functional and the gradient-corrected functional of Lee, Yang, and Paar [B3LYP] and UDFT LANL2DZ B3LYP) quantum-chemical calculations has been studied the complexation CO and NO with molecular hydroxide of copper(I). The influence of charge defects has been simulated by the calculations of anionic, neutral, and cationic systems. It is shown that CO and NO are mainly coordinated by nonoxygen atom on an atom of copper(I) hydroxide as one- and two-center forms. These forms are suitable for appearance of prereactionary complexes of catalytic oxidation CO by molecular oxygen and decomposition NO into atoms of nitrogen and oxygen. The corresponding prereactionary complexes for systems with participation of copper(II) hydroxide and copper(III) hydroxide are not revealed. The calculations predict inhibiting impact of copper(II) and copper(III) of the observed reactions. Computed stability of complexes CO and NO with copper(I) hydroxide and activation energy of catalytic conversion of monooxides essentially depend on an excessive charge of the system. Introduction of electron-donating additives into copper(I) hydroxide promotes rise of catalytic activity of copper(I) compound.

Blue copper model complexes with distorted tetragonal geometry acting as effective electron-transfer mediators in dye-sensitized solar cells.

PubMed

Hattori, Shigeki; Wada, Yuji; Yanagida, Shozo; Fukuzumi, Shunichi

2005-07-06

The electron self-exchange rate constants of blue copper model complexes, [(-)-sparteine-N,N'](maleonitriledithiolato-S,S')copper ([Cu(SP)(mmt)])(0/)(-), bis(2,9-dimethy-1,10-phenanthroline)copper ([Cu(dmp)(2)](2+/+)), and bis(1,10-phenanthroline)copper ([Cu(phen)(2)](2+/+)) have been determined from the rate constants of electron transfer from a homologous series of ferrocene derivatives to the copper(II) complexes in light of the Marcus theory of electron transfer. The resulting electron self-exchange rate constant increases in the order: [Cu(phen)(2)](2+/+) < [Cu(SP)(mmt)](0/)(-) < [Cu(dmp)(2)](2+/+), in agreement with the order of the smaller structural change between the copper(II) and copper(I) complexes due to the distorted tetragonal geometry. The dye-sensitized solar cells (DSSC) were constructed using the copper complexes as redox couples to compare the photoelectrochemical responses with those using the conventional I(3)(-)/I(-) couple. The light energy conversion efficiency (eta) values under illumination of simulated solar light irradiation (100 mW/cm(2)) of DSSCs using [Cu(phen)(2)](2+/+), [Cu(dmp)(2)](2+/+), and [Cu(SP)(mmt)](0/)(-) were recorded as 0.1%, 1.4%, and 1.3%, respectively. The maximum eta value (2.2%) was obtained for a DSSC using the [Cu(dmp)(2)](2+/+) redox couple under the light irradiation of 20 mW/cm(2) intensity, where a higher open-circuit voltage of the cell was attained as compared to that of the conventional I(3)(-)/I(-) couple.

Heteroleptic Copper(I)-Based Complexes for Photocatalysis: Combinatorial Assembly, Discovery, and Optimization.

PubMed

Minozzi, Clémentine; Caron, Antoine; Grenier-Petel, Jean-Christophe; Santandrea, Jeffrey; Collins, Shawn K

2018-05-04

A library of 50 copper-based complexes derived from bisphosphines and diamines was prepared and evaluated in three mechanistically distinct photocatalytic reactions. In all cases, a copper-based catalyst was identified to afford high yields, where new heteroleptic complexes derived from the bisphosphine BINAP displayed high efficiency across all reaction types. Importantly, the evaluation of the library of copper complexes revealed that even when photophysical data is available, it is not always possible to predict which catalyst structure will be efficient or inefficient in a given process, emphasizing the advantages for catalyst structures with high modularity and structural variability. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hybrid copper complex-derived conductive patterns printed on polyimide substrates

NASA Astrophysics Data System (ADS)

Lee, Byoungyoon; Jeong, Sooncheol; Kim, Yoonhyun; Jeong, Inbum; Woo, Kyoohee; Moon, Jooho

2012-06-01

We synthesized new copper complexes that can be readily converted into highly conductive Cu film. Mechanochemical milling of copper (I) oxide suspended in formic acid resulted in the submicron-sized Cu formate together Cu nanoparticles. The submicrometer-sized Cu formates are reactive toward inter-particle sintering and metallic Cu seeds present in the Cu complexes assist their decomposition and the nucleation of Cu. The hybrid copper complex film printed on polyimide substrate is decomposed into dense and uniform Cu layer after annealing at 250 °C for 30 min under nitrogen atmosphere. The resulting Cu film exhibited a low resistivity of 8.2 μΩ·cm and good adhesion characteristics.

Copper Complexation Screen Reveals Compounds with Potent Antibiotic Properties against Methicillin-Resistant Staphylococcus aureus

PubMed Central

Haeili, Mehri; Moore, Casey; Davis, Christopher J. C.; Cochran, James B.; Shah, Santosh; Shrestha, Tej B.; Zhang, Yaofang; Bossmann, Stefan H.; Benjamin, William H.

2014-01-01

Macrophages take advantage of the antibacterial properties of copper ions in the killing of bacterial intruders. However, despite the importance of copper for innate immune functions, coordinated efforts to exploit copper ions for therapeutic interventions against bacterial infections are not yet in place. Here we report a novel high-throughput screening platform specifically developed for the discovery and characterization of compounds with copper-dependent antibacterial properties toward methicillin-resistant Staphylococcus aureus (MRSA). We detail how one of the identified compounds, glyoxal-bis(N4-methylthiosemicarbazone) (GTSM), exerts its potent strictly copper-dependent antibacterial properties on MRSA. Our data indicate that the activity of the GTSM-copper complex goes beyond the general antibacterial effects of accumulated copper ions and suggest that, in contrast to prevailing opinion, copper complexes can indeed exhibit species- and target-specific activities. Based on experimental evidence, we propose that copper ions impose structural changes upon binding to the otherwise inactive GTSM ligand and transfer antibacterial properties to the chelate. In turn, GTSM determines target specificity and utilizes a redox-sensitive release mechanism through which copper ions are deployed at or in close proximity to a putative target. According to our proof-of-concept screen, copper activation is not a rare event and even extends to already established drugs. Thus, copper-activated compounds could define a novel class of anti-MRSA agents that amplify copper-dependent innate immune functions of the host. To this end, we provide a blueprint for a high-throughput drug screening campaign which considers the antibacterial properties of copper ions at the host-pathogen interface. PMID:24752262

Discrete Cu(i) complexes for azide–alkyne annulations of small molecules inside mammalian cells† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7sc04643j

PubMed Central

Miguel-Ávila, Joan; Tomás-Gamasa, María; Olmos, Andrea

2018-01-01

The archetype reaction of “click” chemistry, namely, the copper-promoted azide–alkyne cycloaddition (CuAAC), has found an impressive number of applications in biological chemistry. However, methods for promoting intermolecular annulations of exogenous, small azides and alkynes in the complex interior of mammalian cells, are essentially unknown. Herein we demonstrate that isolated, well-defined copper(i)–tris(triazolyl) complexes featuring designed ligands can readily enter mammalian cells and promote intracellular CuAAC annulations of small, freely diffusible molecules. In addition to simplifying protocols and avoiding the addition of “non-innocent” reductants, the use of these premade copper complexes leads to more efficient processes than with the alternative, in situ made copper species prepared from Cu(ii) sources, tris(triazole) ligands and sodium ascorbate. Under the reaction conditions, the well-defined copper complexes exhibit very good cell penetration properties, and do not present significant toxicities. PMID:29675241

Inhibitory effect of Disulfiram/copper complex on non-small cell lung cancer cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duan, Lincan; Shen, Hongmei; Zhao, Guangqiang

2014-04-18

Highlights: • Disulfiram and copper synergistically inhibit lung cancer cell proliferation. • Lung cancer cell colony formation ability is inhibited by Disulfiram/copper. • Disulfiram/copper increases the sensitivity of cisplatin to lung cancer cells. • Lung cancer stem cells are specifically targeted by Disulfiram/copper complex. - Abstract: Non-small cell lung cancer (NSCLC) is the most common cause of cancer-related death in both men and women worldwide. Recently, Disulfiram has been reported to be able to inhibit glioblastoma, prostate, or breast cancer cell proliferation. In this study, the synergistic effect of Disulfiram and copper on NSCLC cell growth was investigated. Inhibition ofmore » cancer cell proliferation was detected by 1-(4,5-Dimethylthiazol-2-yl)-3,5-diphenylformazan (MTT) assay and cell cycle analysis. Liquid colony formation and tumor spheroid formation assays were used to evaluate their effect on cancer cell clonogenicity. Real-time PCR was performed to test the mRNA level of cancer stem cell related genes. We found that Disulfiram or copper alone did not potently inhibit NSCLC cell proliferation in vitro. However, the presence of copper significantly enhanced inhibitory effect of Disulfiram on NSCLC cell growth, indicating a synergistic effect between Disulfiram and copper. Cell cycle analysis showed that Disulfiram/copper complex caused NSCLC cell cycle arrest in G2/M phase. Furthermore, Disulfiram/copper significantly increased the sensitivity of cisplatin in NSCLC cells tested by MTT assay. Liquid colony formation assay revealed that copper dramatically increased the inhibitory effect of Disulfiram on NSCLC cell colony forming ability. Disulfiram combined with copper significantly attenuated NSCLC cell spheroid formation and recuded the mRNA expression of lung cancer stem cell related genes. Our data suggest that Disulfiram/copper complex alone or combined with other chemotherapy is a potential therapeutic strategy for NSCLC patients.« less

Copper-complexing ligands produced by an intact estuarine microbial community in response to copper stress.

NASA Astrophysics Data System (ADS)

Bingham, J.; Dryden, C.; Gordon, A.

2002-12-01

Copper is both an important nutrient and a pollutant in the marine environment. By studying the interactions between microorganisms and copper in the Elizabeth River (VA), home to a major Naval Base, we field tested the hypothesis that picoplankton and/or bacterioplankton produce strong, copper-complexing ligands in response to elevated copper concentrations. A simple light/ dark test was used to distinguish between heterotrophic and phototrophic ligand production. Samples were bottled and moored, submerged one meter, for a week. Direct counts using DAPI stain and epiflourescence were conducted to find concentrations of picoplankton and bacterioplankton. Using cathodic stripping voltammetry, we found the total copper concentrations, and then from a titration of the ligands by copper, the ligand concentrations and conditional stability constants were obtained. The Elizabeth River naturally had between 10-20 nM total dissolved copper concentrations. However when copper complexation was considered we found that the levels of bio-available Cu(II) ions were much lower. In fact in the natural samples the levels were not high enough to affect the relative reproductive rates of several microorganisms. Naturally there was a 50 nM "buffer zone" of ligand to total dissolved copper concentration. Furthermore, when stressed with excess copper, healthy picoplankton produced enough ligand to alleviate toxicity, and rebuild the buffer zone. However bacterioplankton only produced enough ligand so that they were no longer affected. Therefore, intact estuarine communities regulate copper bioavailability and toxicity with ligand production.

Cationic copper (I) complexes with bulky 1,4-diaza-1,3-butadiene ligands - Synthesis, solid state structure and catalysis

NASA Astrophysics Data System (ADS)

Anga, Srinivas; Kottalanka, Ravi K.; Pal, Tigmansu; Panda, Tarun K.

2013-05-01

We report the full characterization of two glyoxal-based ligands N,N bis(diphenylmethyl)-1,4-diaza-1,3-butadiene ligand (DADPh2, 1) and more bulky N,N bis(triphenylmethyl)-1,4-diaza-1,3-butadiene ligand (DADPh3, 2) by the condensation reaction of glyoxal and diphenylmethanamine and triphenyl-methanamine respectively. The copper (I) complex of composition [Cu(DADPh2)2]PF6 (3) having two neutral bidentate N,N bis(diphenyl-methyl)-1,4-diaza-1,3-butadiene ligand was prepared by the reaction of [Cu(CH3CN)4]PF6 and 1 in 1:2 ratio in dichloromethane. In a similar reaction with N,N bis(triphenylmethyl)-1,4-diaza-1,3-butadiene ligand (2) and [Cu(CH3CN)4]PF6 in dichloromethane yielded corresponding heteroleptic copper (I) complex [Cu(DADPh3)(CH3CN)2]PF6 (4). Another copper (I) complex [Cu(DADPh2)(PPh3)]PF6 (5) can also be obtained by the one pot reaction involving ligand 1, [Cu(CH3CN)4]PF6 and triphenylphosphine. Solid state structures of all the five compounds were established by single crystal X-ray diffraction analysis. The solid state structures of the copper complexes 3-5 reveal a distorted tetrahedral geometry around the copper (I) centers. The copper complexes 3-5 were tested as catalysts for the coupling reaction of o-iodophenol and phenyl acetylene and it was observed that complex 4 exhibits the highest catalytic activity.

Copper Complex in Poly(vinyl chloride) as a Nitric Oxide-Generating Catalyst for the Control of Nitrifying Bacterial Biofilms.

PubMed

Wonoputri, Vita; Gunawan, Cindy; Liu, Sanly; Barraud, Nicolas; Yee, Lachlan H; Lim, May; Amal, Rose

2015-10-14

In this study, catalytic generation of nitric oxide by a copper(II) complex embedded within a poly(vinyl chloride) matrix in the presence of nitrite (source of nitric oxide) and ascorbic acid (reducing agent) was shown to effectively control the formation and dispersion of nitrifying bacteria biofilms. Amperometric measurements indicated increased and prolonged generation of nitric oxide with the addition of the copper complex when compared to that with nitrite and ascorbic acid alone. The effectiveness of the copper complex-nitrite-ascorbic acid system for biofilm control was quantified using protein analysis, which showed enhanced biofilm suppression when the copper complex was used in comparison to that with nitrite and ascorbic acid treatment alone. Confocal laser scanning microscopy (CLSM) and LIVE/DEAD staining revealed a reduction in cell surface coverage without a loss of viability with the copper complex and up to 5 mM of nitrite and ascorbic acid, suggesting that the nitric oxide generated from the system inhibits proliferation of the cells on surfaces. Induction of nitric oxide production by the copper complex system also triggered the dispersal of pre-established biofilms. However, the addition of a high concentration of nitrite and ascorbic acid to a pre-established biofilm induced bacterial membrane damage and strongly decreased the metabolic activity of planktonic and biofilm cells, as revealed by CLSM with LIVE/DEAD staining and intracellular adenosine triphosphate measurements, respectively. This study highlights the utility of the catalytic generation of nitric oxide for the long-term suppression and removal of nitrifying bacterial biofilms.

BSA binding and antimicrobial studies of branched polyethyleneimine-copper(II)bipyridine/phenanthroline complexes

NASA Astrophysics Data System (ADS)

Vignesh, Gopalaswamy; Arunachalam, Sankaralingam; Vignesh, Sivanandham; James, Rathinam Arthur

2012-10-01

The interaction of two water soluble branched polyethyleneimine-copper(II) complexes containing bipyridine/phenanthroline with bovine serum albumin (BSA) was studied by, UV-Visible absorption, fluorescence, lifetime measurements and circular dichroism spectroscopic techniques. The polymer-copper(II) complexes strongly quench the intrinsic fluorescence of BSA is the static quenching mechanism through hydrogen bonds and van der Waal's attraction. The distance r, between the BSA and the complexes seems to be less than 2 nm indicating that the energy transfer between the donor and acceptor occurs with high probability. Synchronous fluorescence studies indicate the binding of polymer-copper(II) complexes with BSA mostly changes the polarity around tryptophan residues rather than tyrosine residues. The circular dichroism studies indicate that the binding has induced considerable amount of conformational changes in the protein. The complexes also show some antibacterial and antifungal properties.

ON THE RELATIVE STABILITY OF ALUMINUM, TITANIUM, VANADIUM, IRON, AND COPPER TARTRATE COMPLEXES IN ALKALI MEDIA (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pyatnitskii, I.V.; Kostyshina, A.P.

1959-06-01

The stability of aluminum, copper, iron, titunium, and vanadium tartrate complexes was determined using bond magnitudes as criteria (the ratio between the concentrations of complexed and free ions at a certain standard acid condition). A method is suggested for determining the ratio of the bonds combining the complexes of two metals. The partition constaats of aluminum, copper, iron(III), and vanadium hydroxyquinolinates between the aqueous solution and chloroform were 2.6 x 10/sup -33/, 7.3 x 10/sup -23/, 1.5 x 10/sup -37/, and 4.2 x 10/sup -23/, respectively. The relative stability of copper and iron turtrate complexes in alkali solution (pH 13)more » and aluminum, iron(III), titunium, and vanadium(IV) tartrate complexes in ammonium solution (pH 9.5) was determined. (R.V.J.)« less

N-benzoylated 1,4,8,11-tetraazacyclotetradecane and their copper(II) and nickel(II) complexes: Spectral, magnetic, electrochemical, crystal structure, catalytic and antimicrobial studies

NASA Astrophysics Data System (ADS)

Nirmala, G.; Rahiman, A. Kalilur; Sreedaran, S.; Jegadeesh, R.; Raaman, N.; Narayanan, V.

2010-09-01

A series of N-benzoylated cyclam ligands incorporating three different benzoyl groups 1,4,8,11-tetra-(benzoyl)-1,4,8,11-tetraazacyclotetradecane (L 1), 1,4,8,11-tetra-(2-nitrobenzoyl)-1,4,8,11-tetraazacyclotetradecane (L 2) and 1,4,8,11-tetra-(4-nitrobenzoyl)-1,4,8,11-tetraazacyclotetradecane (L 3) and their nickel(II) and copper(II) complexes are described. Crystal structure of L 1 is also reported. The ligands and complexes were characterized by elemental analysis, electronic, IR, 1H NMR and 13C NMR spectral studies. N-benzoylation causes red shift in the λmax values of the complexes. The cyclic voltammogram of the complexes of ligand L 1 show one-electron, quasi-reversible reduction wave in the region -1.00 to -1.04 V, whereas that of L 2 and L 3 show two quasi-reversible reduction peaks. Nickel complexes show one-electron quasi-reversible oxidation wave at a positive potential in the range +1.05 to +1.15 V. The ESR spectra of the mononuclear copper(II) complexes show four lines, characteristic of square-planar geometry with nuclear hyperfine spin 3/2. All copper(II) complexes show a normal room temperature magnetic moment values μeff 1.70-1.73 BM which is close to the spin-only value of 1.73 BM. Kinetic studies on the oxidation of pyrocatechol to o-quinone using the copper(II) complexes as catalysts and hydrolysis of 4-nitrophenylphosphate using the copper(II) and nickel(II) complexes as catalysts were carried out. All the ligands and their complexes were also screened for antimicrobial activity against Gram-positive, Gram-negative bacteria and human pathogenic fungi.

Copper and Antibiotics: Discovery, Modes of Action, and Opportunities for Medicinal Applications.

PubMed

Dalecki, Alex G; Crawford, Cameron L; Wolschendorf, Frank

2017-01-01

Copper is a ubiquitous element in the environment as well as living organisms, with its redox capabilities and complexation potential making it indispensable for many cellular functions. However, these same properties can be highly detrimental to prokaryotes and eukaryotes when not properly controlled, damaging many biomolecules including DNA, lipids, and proteins. To restrict free copper concentrations, all bacteria have developed mechanisms of resistance, sequestering and effluxing labile copper to minimize its deleterious effects. This weakness is actively exploited by phagocytes, which utilize a copper burst to destroy pathogens. Though administration of free copper is an unreasonable therapeutic antimicrobial itself, due to insufficient selectivity between host and pathogen, small-molecule ligands may provide an opportunity for therapeutic mimicry of the immune system. By modulating cellular entry, complex stability, resistance evasion, and target selectivity, ligand/metal coordination complexes can synergistically result in high levels of antibacterial activity. Several established therapeutic drugs, such as disulfiram and pyrithione, display remarkable copper-dependent inhibitory activity. These findings have led to development of new drug discovery techniques, using copper ions as the focal point. High-throughput screens for copper-dependent inhibitors against Mycobacterium tuberculosis and Staphylococcus aureus uncovered several new compounds, including a new class of inhibitors, the NNSNs. In this review, we highlight the microbial biology of copper, its antibacterial activities, and mechanisms to discover new inhibitors that synergize with copper. © 2017 Elsevier Ltd. All rights reserved.

Spectroscopic and structural study of the newly synthesized heteroligand complex of copper with creatinine and urea.

PubMed

Gangopadhyay, Debraj; Singh, Sachin Kumar; Sharma, Poornima; Mishra, Hirdyesh; Unnikrishnan, V K; Singh, Bachcha; Singh, Ranjan K

2016-02-05

Study of copper complex of creatinine and urea is very important in life science and medicine. In this paper, spectroscopic and structural study of a newly synthesized heteroligand complex of copper with creatinine and urea has been discussed. Structural studies have been carried out using DFT calculations and spectroscopic analyses were carried out by FT-IR, Raman, UV-vis absorption and fluorescence techniques. The copper complex of creatinine and the heteroligand complex were found to have much increased water solubility as compared to pure creatinine. The analysis of FT-IR and Raman spectra helps to understand the coordination properties of the two ligands and to determine the probable structure of the heteroligand complex. The LIBS spectra of the heteroligand complex reveal that the complex is free from other metal impurities. UV-visible absorption spectra and the fluorescence emission spectra of the aqueous solution of Cu-Crn-urea heteroligand complex at different solute concentrations have been analyzed and the complex is found to be rigid and stable in its monomeric form at very low concentrations. Copyright © 2015 Elsevier B.V. All rights reserved.

Copper complexation screen reveals compounds with potent antibiotic properties against methicillin-resistant Staphylococcus aureus.

PubMed

Haeili, Mehri; Moore, Casey; Davis, Christopher J C; Cochran, James B; Shah, Santosh; Shrestha, Tej B; Zhang, Yaofang; Bossmann, Stefan H; Benjamin, William H; Kutsch, Olaf; Wolschendorf, Frank

2014-07-01

Macrophages take advantage of the antibacterial properties of copper ions in the killing of bacterial intruders. However, despite the importance of copper for innate immune functions, coordinated efforts to exploit copper ions for therapeutic interventions against bacterial infections are not yet in place. Here we report a novel high-throughput screening platform specifically developed for the discovery and characterization of compounds with copper-dependent antibacterial properties toward methicillin-resistant Staphylococcus aureus (MRSA). We detail how one of the identified compounds, glyoxal-bis(N4-methylthiosemicarbazone) (GTSM), exerts its potent strictly copper-dependent antibacterial properties on MRSA. Our data indicate that the activity of the GTSM-copper complex goes beyond the general antibacterial effects of accumulated copper ions and suggest that, in contrast to prevailing opinion, copper complexes can indeed exhibit species- and target-specific activities. Based on experimental evidence, we propose that copper ions impose structural changes upon binding to the otherwise inactive GTSM ligand and transfer antibacterial properties to the chelate. In turn, GTSM determines target specificity and utilizes a redox-sensitive release mechanism through which copper ions are deployed at or in close proximity to a putative target. According to our proof-of-concept screen, copper activation is not a rare event and even extends to already established drugs. Thus, copper-activated compounds could define a novel class of anti-MRSA agents that amplify copper-dependent innate immune functions of the host. To this end, we provide a blueprint for a high-throughput drug screening campaign which considers the antibacterial properties of copper ions at the host-pathogen interface. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Storm water runoff measurements of copper from a naturally patinated roof and from a parking space. Aspects on environmental fate and chemical speciation.

PubMed

Odnevall Wallinder, I; Hedberg, Y; Dromberg, P

2009-12-01

Release of copper from a naturally aged copper roof on a shopping centre building in a suburban site of Stockholm has been measured during different rain events after its interaction with the internal drainage system and storm drains made of cast iron and concrete. Concentrations of copper removed by means of urban storm water from a nearby parking space have been determined for comparison. Predictions and measurements of the chemical speciation of released copper are discussed compared to the total concentration, and to threshold values for freshwater and drinking water. The results clearly illustrate that the major part of the released copper from the roof is readily retained already during transport through the internal drainage system of the building, a pathway that also changes the chemical speciation of released copper and its bioavailable fraction. Most copper, not retained by cast iron and concrete surfaces, was strongly complexed to organic matter. The median concentration of free cupric ions and weak copper complexes was less than, or within the range of reported no effect concentrations, NOECs, of copper in surface waters. The parking space contributed with significantly higher and time-dependent concentrations of total copper compared to measured concentrations of copper from the roof after the interaction with the drainage system. Most copper in the surface runoff water was strongly complexed with organic matter, hence reducing the bioavailable fraction significantly to concentrations within the NOEC range. Dilution with other sources of urban storm water will reduce the released concentration of copper even further. The results illustrate that already the internal drainage system and the storm drains made of cast iron and concrete act as efficient sinks for released copper which means that any installation of additional infiltration devices is redundant.

All-metal aromatic cationic palladium triangles can mimic aromatic donor ligands with Lewis acidic cations† †Electronic supplementary information (ESI) available: Reaction procedures, characterization of complexes, copies of all spectra and cif files, modelling details and XYZ coordinates. CCDC 1410440–1410442. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc03475j Click here for additional data file. Click here for additional data file.

PubMed Central

Wang, Yanlan; Monfredini, Anna; Deyris, Pierre-Alexandre; Blanchard, Florent; Derat, Etienne; Malacria, Max

2017-01-01

We present that cationic rings can act as donor ligands thanks to suitably delocalized metal–metal bonds. This could grant parent complexes with the peculiar properties of aromatic rings that are crafted with main group elements. We assembled Pd nuclei into equilateral mono-cationic triangles with unhindered faces. Like their main group element counterparts and despite their positive charge, these noble-metal rings form stable bonding interactions with other cations, such as positively charged silver atoms, to deliver the corresponding tetranuclear dicationic complexes. Through a mix of modeling and experimental techniques we propose that this bonding mode is an original coordination-like one rather than a 4-centre–2-electron bond, which have already been observed in three dimensional aromatics. The present results thus pave the way for the use of suitable metal rings as ligands. PMID:29163890

Organogold oligomers: Exploiting iClick and aurophilic cluster formation to prepare solution stable Au 4 repeating units

DOE PAGES

Yang, Xi; Wang, Shanshan; Ghiviriga, Ion; ...

2015-05-19

A novel synthetic method to create gold based metallo–oligomers/polymers via the combination of inorganic click (iClick) with intermolecular aurophilic interactions is demonstrated. Complexes [PEt 3Au] 4(μ-N 3C 2C 6H 5) (1) and [PPhMe 2Au] 43C 2C 6H 5) (2) and {[PEt 3Au] 4[(μ-N 3C 2) 2-9,9-dihexyl-9H-fluorene]} n (8) have been synthesized via iClick. The tetranuclear structures of 1 and 2, induced by aurophilic bonding, are confirmed in the solid state through single crystal X-ray diffraction experiments and in solution via variable temperature NMR spectroscopy. The extended 1D structure of 8 is constructed by aurophilic induced self-assembly. 1H DOSY NMR analysismore » reveals that the aurophilic bonds in 1, 2, and 8 are retained in the solution phase. The degree of polymerization within complex 8 is temperature and concentration dependent, as determined by 1H DOSY NMR. The complex 8 is a rare example of a solution stable higher ordered structure linked by aurophilic interactions.« less

[(H2O)(terpy)Mn(μ-O)2Mn(terpy)(OH2)](NO3)3 (terpy = 2,2′:6,2″-terpyridine) and its relevance to the oxygen-evolving complex of photosystem II examined through pH dependent cyclic voltametry

PubMed Central

Cady, Clyde W.; Shinopoulos, Katherine E.; Crabtree, Robert H.; Brudvig, Gary W.

2010-01-01

Photosynthetic water oxidation occurs naturally at a tetranuclear manganese center in the photosystem II protein complex. Synthetically mimicking this tetramanganese center, known as the oxygen-evolving complex (OEC), has been an ongoing challenge of bioinorganic chemistry. Most past efforts have centered on water-oxidation catalysis using chemical oxidants. However, solar energy applications have drawn attention to electrochemical methods. In this paper, we examine the electrochemical behavior of the biomimetic water-oxidation catalyst [(H2O)(terpy)Mn(μ-O)2Mn(terpy)(H2O)](NO3)3 [terpy = 2,2′:6′,2″-terpyridine] (1) in water under a variety of pH and buffered conditions and in the presence of acetate that binds to 1 in place of one of the terminal water ligands. These experiments will show that 1 not only exhibits proton-coupled electron-transfer reactivity analogous to the OEC, but also may be capable of electrochemical oxidation of water to oxygen. PMID:20372724

An Ru(II)-Fe(III) bimetallic complex as a multifunctional device for detecting, signal amplifying, and degrading oxalate.

PubMed

Chow, Cheuk-Fai; Ho, Pui-Yu; Gong, Cheng-Bin

2014-09-07

A tetranuclear bimetallic complex, [Ru(II)((t)Bubpy)(CN)4]2-[Fe(III)(H2O)3Cl]2·8H2O (1) has been synthesized and characterized. It was found to be a multifunctional device that can detect, signal amplify, and degrade an organic pollutant, oxalate. Results of the chemosensing studies of 1 toward common anions show that only oxalate selectively induces naked-eye colorimetric and luminometric responses with method detection limits down to 78.7 and 5.5 ppm, respectively from 1. Meanwhile, results of the photo-degradation studies of 1 toward oxalate show that the dissolved organic carbon content of oxalate decreased and reached complete mineralization into CO2 within 6 hours. Complex 1 was also found as the catalyst that amplified the detection signal toward oxalate. Through the photoassisted Fenton reaction by 1, methyl orange, an additional coloring agent, could be degraded so that the visual detection limit of 1 toward oxalate was magnified 50 times from 100 to 2 ppm. The detection, degradation, mineralization and signal amplification were found applicable in real water bodies such as river, pond and underground water with excellent recoveries and relative standard deviation.

Structural measurements and cell line studies of the copper-PEG-Rifampicin complex against Mycobacterium tuberculosis.

PubMed

Manning, Thomas; Mikula, Rachel; Wylie, Greg; Phillips, Dennis; Jarvis, Jackie; Zhang, Fengli

2015-02-01

The bacterium responsible for tuberculosis is increasing its resistance to antibiotics resulting in new multidrug-resistant Mycobacterium tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB). In this study, several analytical techniques including NMR, FT-ICR, MALDI-MS, LC-MS and UV/Vis are used to study the copper-Rifampicin-Polyethylene glycol (PEG-3350) complex. The copper (II) cation is a carrier for the antibiotic Rifampicin as well as nutrients for the bacterium. The NIH-NIAID cell line containing several Tb strains (including antibiotic resistant strains) is tested against seven copper-PEG-RIF complex variations. Copyright © 2014 Elsevier Ltd. All rights reserved.

Bioinorganic Chemical Modeling of Dioxygen-Activating Copper Proteins.

ERIC Educational Resources Information Center

Karlin, Kenneth D.; Gultneh, Yilma

1985-01-01

Discusses studies done in modeling the copper centers in the proteins hemocyanin (a dioxygen carrier), tyrosinase, and dopamine beta-hydroxylase. Copper proteins, model approach in copper bioinorganic chemistry, characterization of reversible oxygen carriers and dioxygen-metal complexes, a copper mono-oxygenase model reaction, and other topics are…

Complex electronic waste treatment - An effective process to selectively recover copper with solutions containing different ammonium salts.

PubMed

Sun, Z H I; Xiao, Y; Sietsma, J; Agterhuis, H; Yang, Y

2016-11-01

Recovery of valuable metals from electronic waste has been highlighted by the EU directives. The difficulties for recycling are induced by the high complexity of such waste. In this research, copper could be selectively recovered using an ammonia-based process, from industrially processed information and communication technology (ICT) waste with high complexity. A detailed understanding on the role of ammonium salt was focused during both stages of leaching copper into a solution and the subsequent step for copper recovery from the solution. By comparing the reactivity of the leaching solution with different ammonium salts, their physiochemical behaviour as well as the leaching efficiency could be identified. The copper recovery rate could reach 95% with ammonium carbonate as the leaching salt. In the stage of copper recovery from the solution, electrodeposition was introduced without an additional solvent extraction step and the electrochemical behaviour of the solution was figured out. With a careful control of the electrodeposition conditions, the current efficiency could be improved to be 80-90% depending on the ammonia salts and high purity copper (99.9wt.%). This research provides basis for improving the recyclability and efficiency of copper recovery from such electronic waste and the whole process design for copper recycling. Copyright © 2016 Elsevier Ltd. All rights reserved.

Synthesis and Cytotoxic Evaluation of Steroidal Copper (Cu (II)) Complexes

PubMed Central

Huang, Yanmin; Kong, Erbin; Zhan, Junyan; Chen, Shuang; Gan, Chunfang; Liu, Zhiping; Pang, Liping

2017-01-01

Using estrone and pregnenolone as starting materials, some steroidal copper complexes were synthesized by the condensation of steroidal ketones with thiosemicarbazide or diazanyl pyridine and then complexation of steroidal thiosemicarbazones or steroidal diazanyl pyridines with Cu (II). The complexes were characterized by IR, NMR, and HRMS. The synthesized compounds were screened for their cytotoxicity against HeLa, Bel-7404, and 293T cell lines in vitro. The results show that all steroidal copper (II) complexes display obvious antiproliferative activity against the tested cancer cells. The IC50 values of complexes 5 and 12 against Bel-7404 (human liver carcinoma) are 5.0 and 7.0 μM. PMID:29180937

A series of silver(I) coordination polymers with saccarinate and flexible aliphatic diamines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yeşilel, Okan Zafer, E-mail: yesilel@ogu.edu.tr; Karamahmut, Bingül; Semerci, Fatih

A series of Ag(I) complexes with aliphatic diamines having a different chain length (NH{sub 2}-(CH{sub 2}){sub n}-NH{sub 2}, n=4–9), with the formulas, [Ag(μ-sac)(μ-db){sub 0.5}]{sub n} (1), ([Ag{sub 4}(sac){sub 4}(μ-dp){sub 2}]·4H{sub 2}O){sub n} (2){sub ,} ([Ag{sub 2}(sac){sub 2}(μ-dz)]·2H{sub 2}O){sub n} (3), ([Ag{sub 2}(sac){sub 2}(μ-dh)]·H{sub 2}O){sub n} (4), ([Ag{sub 2}(sac){sub 2}(μ-do)]·H{sub 2}O){sub n} (5a), [Ag{sub 2}(sac){sub 2}(μ-do){sub 2}] (5b) and [Ag{sub 4}(sac){sub 4}(μ-dn){sub 2}]·2H{sub 2}O (6), where sac=saccharinate, db=1,4-diaminobutane, dp=1,5-diaminopentane, dz=1,6-diaminohexane, dh=1,7-diaminoheptane, do=1,8-diaminooctane and dn=1,9-diaminononane, were synthesized and characterized by elemental analysis, infrared spectra and single-crystal X-ray diffraction analysis. In 1, the sac ligand bridges adjacent Ag(I) ions through the nitrogen andmore » carbonyl oxygen atoms to form eight-membered bimetallic rings with the Ag···Ag distance being 3.897 Å, which are linked by db ligands to give a 1D zigzag chain. The complexes 2–5a consist of a one-dimensional (1D) linear cationic chains and discrete mononuclear anions. The discreet complex units are further connected by ligand unsupported argentophilic interactions. In 6, the dn ligands bridge adjacent silver centers to form 24-membered macrometallacyclic rings, which are further connected to the anionic [Ag(sac){sub 2}]{sup -} units by argentophilic Ag1···Ag2 interactions to form a tetranuclear structure. The adjacent dinuclear units are further linked together through ligand-unsupported argentophilic Ag···Ag (3.207(1) Å) interactions, generating a one-dimensional linear chain. The most striking feature of complexes is the presence of the rare intermolecular C-H···Ag interactions. In 5b, the do ligand bridges two Ag(I) ions to form a dinuclear with a 22-membered macrometallacyclic ring. Furthermore, biological activities, luminescence properties and thermal analysis (TG/DTA) of the complexes were investigated. - Graphical abstract: In this study, six new silver coordination compounds were synthesized by using saccharinate and flexible aliphatic diamine derivatives. All the compounds were characterized by elemental analysis, IR and single-crystal X-ray analysis. TG/DTA. Furthermore, biological activities, luminescence properties and thermal analysis (TG/DTA) of the complexes have been investigated. Complexes 1–5a and 6 were synthesized with the same reactant ratio and room temperature by using a mixture of AgNO{sub 3}, sac and different length diamine derivatives. The complex 5b is also synthesized was similar to that of 1 at 80 °C. In the complexes, the diamine derivatives ligands show bis(bridging) coordination mode. The sac ligand exhibits a µ-bridging coordination mode in 1 and N-donor monodentate coordination mode in 2–6. Complexes 1–5 exhibit 1D chain structure while complex 6 are tetranuclear structure. In the crystal packing of complexes, 3D supramolecular frameworks are formed via C-H···Ag, Ag···π and Ag···Ag interactions.« less

Heptacopper(II) and dicopper(II)-adenine complexes: synthesis, structural characterization, and magnetic properties

DOE PAGES

Leite Ferreira, B. J. M.; Brandão, Paula; Dos Santos, A. M.; ...

2015-07-13

The syntheses, crystal structures, and magnetic properties of two new copper(II) complexes with molecular formulas [Cu 7(μ 2-OH 2) 6(μ 3-O) 6(adenine) 6(NO 3) 26H 2O (1) and [Cu 2(μ 2-H 2O) 2(adenine) 2(H 2O) 4](NO 3) 42H 2O (2) are reported. We composed the heptanuclear compound of a central octahedral CuO 6 core sharing edges with six adjacent copper octahedra. In 2, the copper octahedra shares one equatorial edge. In both compounds, these basic copper cluster units are further linked by water bridges and bridging adenine ligands through N3 and N9 donors. All copper(II) centers exhibit Jahn-Teller distorted octahedralmore » coordination characteristic of a d 9 center. Our study of the magnetic properties of the heptacopper complex revealed a dominant ferromagnetic intra-cluster interaction, while the dicopper complex exhibits antiferromagnetic intra-dimer interactions with weakly ferromagnetic inter-dimer interaction.« less

The electronic spectra and the structures of the individual copper(II) chloride and bromide complexes in acetonitrile according to steady-state absorption spectroscopy and DFT/TD-DFT calculations

NASA Astrophysics Data System (ADS)

Olshin, Pavel K.; Myasnikova, Olesya S.; Kashina, Maria V.; Gorbunov, Artem O.; Bogachev, Nikita A.; Kompanets, Viktor O.; Chekalin, Sergey V.; Pulkin, Sergey A.; Kochemirovsky, Vladimir A.; Skripkin, Mikhail Yu.; Mereshchenko, Andrey S.

2018-03-01

The results of spectrophotometric study and quantum chemical calculations for copper(II) chloro- and bromocomplexes in acetonitrile are reported. Electronic spectra of the individual copper(II) halide complexes were obtained in a wide spectral range 200-2200 nm. Stability constants of the individual copper(II) halide complexes in acetonitrile were calculated: log β1 = 8.5, log β2 = 15.6, log β3 = 22.5, log β4 = 25.7 for [CuCln]2-n and log β1 = 17.0, log β2 = 24.6, log β3 = 28.1, log β4 = 30.4 for [CuBrn]2-n. Structures of the studied complexes were optimized and electronic spectra were simulated using DFT and TD-DFT methodologies, respectively. According to the calculations, the more is the number of halide ligands the less is coordination number of copper ion.

Ternary copper(II) complexes with amino acid chains and heterocyclic bases: DNA binding, cytotoxic and cell apoptosis induction properties.

PubMed

Ma, Tieliang; Xu, Jun; Wang, Yuan; Yu, Hao; Yang, Yong; Liu, Yang; Ding, Weiliang; Zhu, Wenjiao; Chen, Ruhua; Ge, Zhijun; Tan, Yongfei; Jia, Lei; Zhu, Taofeng

2015-03-01

Nowadays, chemotherapy is a common means of oncology. However, it is difficult to find excellent chemotherapy drugs. Here we reported three new ternary copper(II) complexes which have potential chemotherapy characteristics with reduced Schiff base ligand and heterocyclic bases (TBHP), [Cu(phen)(TBHP)]H2O (1), [Cu(dpz)(TBHP)]H2O (2) and [Cu(dppz)(TBHP)]H2O (3) (phen=1,10-phenanthroline, dpz=dipyrido [3,2:2',3'-f]quinoxaline, dppz=dipyrido [3,2-a:2',3'-c]phenazine, H2TBHP=2-(3,5-di-tert-butyl-2-hydroxybenzylamino)-2-benzyl-acetic acid). The DNA-binding properties of the complexes were investigated by spectrometric titrations, ethidium bromide displacement experiments and viscosity measurements. The results indicated that the three complexes, especially the complex 13, can strongly bind to calf-thymus DNA (CT-DNA). The intrinsic binding constants Kb of the ternary copper(II) complexes with CT-DNA were 1.37×10(5), 1.81×10(5) and 3.21×10(5) for 1, 2 and 3 respectively. Comparative cytotoxic activities of the copper(II) complexes were also determined by 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results showed that the ternary copper(II) complexes had significant cytotoxic activity against the human lung cancer (A549), human esophageal cancer (Eca109) and human gastric cancer (SGC7901) cell lines. Cell apoptosis were detected by AnnexinV/PI flow cytometry and by Western blotting with the protein expression of p53, Bax and Bcl-2. All the three copper complexes can effectively induce apoptosis of the three human tumor cells. Copyright © 2014 Elsevier Inc. All rights reserved.

Reduction of paraquat-induced renal cytotoxicity by manganese and copper complexes of EGTA and EHPG.

PubMed

Samai, Mohamed; Hague, Theresa; Naughton, Declan P; Gard, Paul R; Chatterjee, Prabal K

2008-02-15

Superoxide anion generation plays an important role in the development of paraquat toxicity. Although superoxide dismutase mimetics (SODm) have provided protection against organ injury involving generation of superoxide anions, they often suffer problems, e.g., regarding their bioavailability or potential pro-oxidant activity. The aim here was to investigate and compare the therapeutic potential of two novel SODm, manganese(II) and copper(II) complexes of the calcium chelator ethylenebis(oxyethylenenitrilo)tetraacetic acid (EGTA) and of the contrast agent ethylenebis(hydroxyphenylglycine) (EHPG), against paraquat-induced renal toxicity in vitro. Incubation of renal NRK-52E cells with paraquat (1 mM) for 24 h produced submaximal, yet significant, reduction in cellular viability and cell death and produced significant increases in superoxide anion and hydroxyl radical generation. Manganese and copper complexes of EGTA (10-100 microM) and EHPG (30-100 microM) reduced paraquat-induced renal cell toxicity and reduced superoxide anion and hydroxyl radical generation significantly. Manganese complexes displayed greater efficacy than copper complexes and, at equivalent concentrations, manganese complexed with EHPG provided the greatest protection. Furthermore, these metal complexes did not interfere with the uptake of [methyl-(14)C]paraquat into NRK-52E cells, suggesting that they provided protection against paraquat cytotoxicity via intracellular mechanisms. These complexes did not display cytotoxicity at the concentrations examined. Together, these results suggest that manganese and copper complexes of EGTA and EHPG, and especially the manganese-EHPG complex, could provide benefit against paraquat nephrotoxicity.

Water oxidation chemistry of photosystem II.

PubMed Central

Vrettos, John S; Brudvig, Gary W

2002-01-01

The O(2)-evolving complex of photosystem II catalyses the light-driven four-electron oxidation of water to dioxygen in photosynthesis. In this article, the steps leading to photosynthetic O(2) evolution are discussed. Emphasis is given to the proton-coupled electron-transfer steps involved in oxidation of the manganese cluster by oxidized tyrosine Z (Y(*)(Z)), the function of Ca(2+) and the mechanism by which water is activated for formation of an O-O bond. Based on a consideration of the biophysical studies of photosystem II and inorganic manganese model chemistry, a mechanism for photosynthetic O(2) evolution is presented in which the O-O bond-forming step occurs via nucleophilic attack on an electron-deficient Mn(V)=O species by a calcium-bound water molecule. The proposed mechanism includes specific roles for the tetranuclear manganese cluster, calcium, chloride, Y(Z) and His190 of the D1 polypeptide. Recent studies of the ion selectivity of the calcium site in the O(2)-evolving complex and of a functional inorganic manganese model system that test key aspects of this mechanism are also discussed. PMID:12437878

Time-resolved vibrational spectroscopy detects protein-based intermediates in the photosynthetic oxygen-evolving cycle.

PubMed

Barry, Bridgette A; Cooper, Ian B; De Riso, Antonio; Brewer, Scott H; Vu, Dung M; Dyer, R Brian

2006-05-09

Photosynthetic oxygen production by photosystem II (PSII) is responsible for the maintenance of aerobic life on earth. The production of oxygen occurs at the PSII oxygen-evolving complex (OEC), which contains a tetranuclear manganese (Mn) cluster. Photo-induced electron transfer events in the reaction center lead to the accumulation of oxidizing equivalents on the OEC. Four sequential photooxidation reactions are required for oxygen production. The oxidizing complex cycles among five oxidation states, called the S(n) states, where n refers to the number of oxidizing equivalents stored. Oxygen release occurs during the S(3)-to-S(0) transition from an unstable intermediate, known as the S(4) state. In this report, we present data providing evidence for the production of an intermediate during each S state transition. These protein-derived intermediates are produced on the microsecond to millisecond time scale and are detected by time-resolved vibrational spectroscopy on the microsecond time scale. Our results suggest that a protein-derived conformational change or proton transfer reaction precedes Mn redox reactions during the S(2)-to-S(3) and S(3)-to-S(0) transitions.

[Biohydrometallurgical technology of a complex copper concentrate process].

PubMed

Murav'ev, M I; Fomchenko, N V; Kondrat'eva, T F

2011-01-01

Leaching of sulfide-oxidized copper concentrate of the Udokan deposit ore with a copper content of 37.4% was studied. In the course of treatment in a sulfuric acid solution with pH 1.2, a copper leaching rate was 6.9 g/kg h for 22 h, which allowed extraction of 40.6% of copper. As a result of subsequent chemical leaching at 80 degrees C during 7 h with a solution of sulphate ferric iron obtained after bio-oxidation by an association of microorganisms, the rate of copper recovery was 52.7 g/kg h. The total copper recovery was 94.5% (over 29 h). Regeneration of the Fe3+ ions was carried out by an association of moderately thermophilic microorganisms, including bacteria of genus Sulfobacillus and archaea of genus Ferroplasma acidiphilum, at 1.0 g/l h at 40 degrees C in the presence of 3% solids obtained by chemical leaching of copper concentrate. A technological scheme of a complex copper concentrate process with the use of bacterial-chemical leaching is proposed.

Cytotoxicity of copper(II)-complexes with some S-alkyl derivatives of thiosalicylic acid. Crystal structure of the binuclear copper(II)-complex with S-ethyl derivative of thiosalicylic acid

NASA Astrophysics Data System (ADS)

Nikolić, Miloš V.; Mijajlović, Marina Ž.; Jevtić, Verica V.; Ratković, Zoran R.; Novaković, Slađana B.; Bogdanović, Goran A.; Milovanović, Jelena; Arsenijević, Aleksandar; Stojanović, Bojana; Trifunović, Srećko R.; Radić, Gordana P.

2016-07-01

The spectroscopically predicted structure of the obtained copper(II)-complex with S-ethyl derivative of thiosalicylic acid was confirmed by X-ray structural study and compared to previously reported crystal structure of the Cu complex with S-methyl derivative. Single crystals suitable for X-ray measurements were obtained by slow crystallization from a water solution. Cytotoxic effects of S-alkyl (R = benzyl (L1), methyl (L2), ethyl (L3), propyl (L4) and butyl (L5)) derivatives of thiosalicylic acid and the corresponding binuclear copper(II)-complexes on murine colon carcinoma cell lines, CT26 and CT26.CL25 and human colon carcinoma cell line HCT-116 were reported here. The analysis of cancer cell viability showed that all the tested complexes had low cytotoxic effect on murine colon carcinoma cell lines, but several times higher cytotoxicity on normal human colon carcinoma cells.

Fluorescence and electron paramagnetic resonance studies of norfloxacin and N-donor mixed-ligand ternary copper(II) complexes: Stability and interaction with SDS micelles

NASA Astrophysics Data System (ADS)

Vignoli Muniz, Gabriel S.; Incio, Jimmy Llontop; Alves, Odivaldo C.; Krambrock, Klaus; Teixeira, Letícia R.; Louro, Sonia R. W.

2018-01-01

The stability of ternary copper(II) complexes of a heterocyclic ligand, L (L being 2,2‧-bipyridine (bipy) or 1,10-phenanthroline (phen)) and the fluorescent antibacterial agent norfloxacin (NFX) as the second ligand was studied at pH 7.4 and different ionic strengths. Fluorescence quenching upon titration of NFX with the binary complexes allowed to obtain stability constants for NFX binding, Kb, as a function of ionic strength. The Kb values vary by more than two orders of magnitude when buffer concentration varies from 0.5 to 100 mM. It was observed that previously synthesized ternary complexes dissociate in buffer according with the obtained stability constants. This shows that equimolar solutions of NFX and binary complexes are equivalent to solutions of synthesized ternary complexes. The interaction of the ternary copper complexes with anionic SDS (sodium dodecyl sulfate) micelles was studied by fluorescence and electron paramagnetic resonance (EPR). Titration of NFX-loaded SDS micelles with the complexes Cu:L allowed to determine the stability constants inside the micelles. Fluorescence quenching demonstrated that SDS micelles increase the stability constants by factors around 50. EPR spectra gave details of the copper(II) local environment, and demonstrated that the structure of the ternary complexes inside SDS micelles is different from that in buffer. Mononuclear ternary complexes formed inside the micelles, while in buffer most ternary complexes are binuclear. The results show that anionic membrane interfaces increase formation of copper fluoroquinolone complexes, which can influence bioavailability, membrane diffusion, and mechanism of action of the antibiotics.

Copper(II) complexes of methimazole, an anti Grave's disease drug. Synthesis, characterization and its potential biological behavior as alkaline phosphatase inhibitor.

PubMed

Urquiza, Nora M; Manca, Silvia G; Moyano, María A; Dellmans, Raquel Arrieta; Lezama, Luis; Rojo, Teófilo; Naso, Luciana G; Williams, Patricia A M; Ferrer, Evelina G

2010-04-01

Methimazole (MeimzH) is an anti-thyroid drug and the first choice for patients with Grave's disease. Two new copper(II) complexes of this drug: [Cu(MeimzH)(2)(NO(3))(2)]*0.5H(2)O and [Cu(MeimzH)(2)(H(2)O)(2)](NO(3))(2)*H(2)O were synthesized and characterized by elemental analysis, dissolution behavior, thermogravimetric analysis and UV-vis, diffuse reflectance, FTIR and EPR spectroscopies. As it is known that copper(II) cation can act as an inhibitor of alkaline phosphatase (ALP), the inhibitory effect of methimazole and its copper(II) complexes on ALP activity has also been investigated.

Copper uptake by the water hyacinth. [Eichornia crassipes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, T.A.; Hardy, J.K.

1987-01-01

Factors affecting Cu/sup +2/ uptake by the water hyacinth (Eichornia crassipes) were examined. Two phases of copper uptake were observed throughout the uptake range (1-1000 mg/1). An initial rapid uptake phase of 4 hours followed by a slower, near linear uptake phase extending past 48 hours was observed. Stirring the solution enhanced uptake, suggesting copper removal is partially diffusion limited. Variations in pH over the range of 3 to 10 did not significantly affect uptake. Increasing the root mass of the plant increased the amount of copper taken up. As solution volume was increased more copper was removed. The presencemore » of complexing agents during the uptake phase reduced copper uptake. The inability of complexing agents to recover all copper initially removed by a plant suggests a migration to sites within the plant.« less

Synthesis, structure and catechol-oxidase activity of copper(II) complexes of 17-hydroxy-16-(N-3-oxo-prop-1-enyl)amino steroids.

PubMed

Wegner, Rainer; Dubs, Manuela; Görls, Helmar; Robl, Christian; Schönecker, Bruno; Jäger, Ernst-G

2002-09-01

Copper is next to iron the most important element in the biological transport, storage and in redox reactions of dioxygen. A bioanalogous activation of dioxygen with copper complexes is used for catalytical epoxidation, allylic hydroxylation and oxidative coupling of aromatic substrates, for example. With stereochemical information in form of chiral ligands, enantioselective reactions may be possible. Another aspect of interest on copper catalyzed reactions with dioxygen is that the exact mechanism and biological function of some enzymes (especially catechol oxidase) is yet not fully clear. For studies mimicking the copper-containing catechol oxidase appropriate chiral steroid ligands with defined stereochemistry and conformation have been synthesized. The four diastereomeric 16,17-aminoalcohols of the 3-methoxy-estra-1,3,5(10)-triene series have been condensed with salicylic aldehyde and different beta-ketoenols to the chiral ligand types 1-5. These compounds with different steric and electronic properties and different arrangements of the neighboring hydroxy and nitrogen functions were reacted with copper(II) acetate to copper complexes. The structure of these complexes will be discussed. The bioanalogous oxidation of 3,5-di-tbutyl-catechol (dtbc) to the corresponding quinone was catalyzed by most of the complexes, indicating their ability to activate dioxygen. The trans configurations c and d showed an activity one magnitude higher than the cis configurations a and b. Comparing compounds with the same diastereomeric configuration, the main influence was that of the peripheral R(1-3) substituents at the beta-ketoenaminic group which are useful for the fine-tuning of the properties of the copper atoms like redox potential and Lewis acidity.

Biochemical characterization of the purple form of Marinobacter hydrocarbonoclasticus nitrous oxide reductase

PubMed Central

Dell'Acqua, Simone; Pauleta, Sofia R.; Moura, José J. G.; Moura, Isabel

2012-01-01

Nitrous oxide reductase (N2OR) catalyses the final step of the denitrification pathway—the reduction of nitrous oxide to nitrogen. The catalytic centre (CuZ) is a unique tetranuclear copper centre bridged by inorganic sulphur in a tetrahedron arrangement that can have different oxidation states. Previously, Marinobacter hydrocarbonoclasticus N2OR was isolated with the CuZ centre as CuZ*, in the [1Cu2+ : 3Cu+] redox state, which is redox inert and requires prolonged incubation under reductive conditions to be activated. In this work, we report, for the first time, the isolation of N2OR from M. hydrocarbonoclasticus in the ‘purple’ form, in which the CuZ centre is in the oxidized [2Cu2+ : 2Cu+] redox state and is redox active. This form of the enzyme was isolated in the presence of oxygen from a microaerobic culture in the presence of nitrate and also from a strictly anaerobic culture. The purple form of the enzyme was biochemically characterized and was shown to be a redox active species, although it is still catalytically non-competent, as its specific activity is lower than that of the activated fully reduced enzyme and comparable with that of the enzyme with the CuZ centre in either the [1Cu2+ : 3Cu+] redox state or in the redox inactive CuZ* state. PMID:22451106

A Mössbauer effect study of the bonding in several organoiron carbonyl clusters

NASA Astrophysics Data System (ADS)

Long, Gary J.; O'Brien, James F.

1988-02-01

After a brief review of the applications of the Mössbauer effect to cyclopentadienyl containing compounds, the chemistry and spectral properties of the various iron carbonyl complexes are described. The electronic properties of a series of trinuclear and tetranuclear organoiron clusters have been investigated through Fenske-Hall self-consistent field molecular orbital calculations, and the results are compared with the Mössbauer effect isomer shifts. A linear correlation is found between the Slater effective nuclear charge, as calculated from the Fenske-Hall partial orbital occupancy factors, and the isomer shift. In these compounds the 4s orbital populations are rather constant. However, the cis and trans isomers of [CpFe(CO)2]2 have a significantly lower 4s orbital populations. In this case, the reduced 4s population must be accounted for by adding it to the effective nuclear charge to obtain a good correlation with the isomer shift.

Photochemistry of copper(II) complexes with macrocyclic amine ligands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muralidharan, S.; Ferraudi, G.

1981-07-01

The photochemical properties of Cu(dl-Me/sub 6/(14)aneN/sub 4/)/sup 2 +/ and Cu(rac-Me/sub 6/(14)aneN/sub 4/)/sup 2 +/ in the presence and absence of axially coordinated ligands have been investigated by continuous and flash irradiations. Flash photolysis of the complexes in deaerated aqueous solutions revealed the presence of copper-ligand radical complexes with closed- and open-cycle ligands. Flash photolysis of methanolic solutions of the complexes, in the presence of halides and pseudohalides, shows Cu(III) macrocyclic intermediates. The experimental observations can be explained in terms of two primary photoprocesses with origins in distinctive charge transfer to metal states. These states have been assigned as aminomore » to copper(II) charge-transfer state and acido to copper(II) charge-transfer state.« less

Copper(II)-bis(thiosemicarbazonato) complexes as anti-chlamydial agents.

PubMed

Marsh, James W; Djoko, Karrera Y; McEwan, Alastair G; Huston, Wilhelmina M

2017-09-29

Lipophilic copper (Cu)-containing complexes have shown promising antibacterial activity against a range of bacterial pathogens. To examine the susceptibility of the intracellular human pathogen Chlamydia trachomatis to copper complexes containing bis(thiosemicarbazone) ligands [Cu(btsc)], we tested the in vitro effect of CuII-diacetyl- and CuII-glyoxal-bis[N(4)-methylthiosemicarbazonato] (Cu(atsm) and Cu(gtsm), respectively) on C. trachomatis. Cu(atsm) and to a greater extent, Cu(gtsm), prevented the formation of infectious chlamydial progeny. Impacts on host cell viability and respiration were also observed in addition to the Chlamydia impacts. This work suggests that copper-based complexes may represent a new lead approach for future development of new therapeutics against chlamydial infections, although host cell impacts need to be fully explored. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Uv Spectroscopy on Gas Phase Cu(I)-BIPYRIDYL Complexes

NASA Astrophysics Data System (ADS)

Xu, Shuang; Christopher, Casey; Weber, J. Mathias

2015-06-01

Transition metal complexes with bipyridine ligands are of great interest in metal-organic chemistry, since they are prototypes for many applications in photochemistry and homogeneous catalysis. Under-coordinated bipyridyl complexes are elusive species in the condensed phase, and the ligand-induced changes in electronic structure are of fundamental interest. We present UV photodissociation spectra of mass-selected monocationic copper(I)-bipyridyl complexes [bpy-Cu-L]+ with different ligands (L = H2O, D2, N2, MeOH, Cl). Complexes were prepared via electrospray ionization of copper/bipyridine solutions followed by accumulation and buffer gas cooling in a cryogenic Paul trap. In addition, we show spectra of similar species based on copper oxide, [bpy-CuO-L]+.

Optimizing the Readout of Lanthanide-DOTA Complexes for the Detection of Ligand-Bound Copper(I).

PubMed

Hanna, Jill R; Allan, Christopher; Lawrence, Charlotte; Meyer, Odile; Wilson, Neil D; Hulme, Alison N

2017-05-14

The CuAAC 'click' reaction was used to couple alkyne-functionalized lanthanide-DOTA complexes to a range of fluorescent antennae. Screening of the antenna components was aided by comparison of the luminescent output of the resultant sensors using data normalized to account for reaction conversion as assessed by IR. A maximum 82-fold enhanced signal:background luminescence output was achieved using a Eu(III)-DOTA complex coupled to a coumarin-azide, in a reaction which is specific to the presence of copper(I). This optimized complex provides a new lead design for lanthanide-DOTA complexes which can act as irreversible 'turn-on' catalytic sensors for the detection of ligand-bound copper(I).

Bismesitoylphosphinic Acid (BAPO-OH): A Ligand for Copper Complexes and Four-Electron Photoreductant for the Preparation of Copper Nanomaterials.

PubMed

Beil, Andreas; Müller, Georgina; Käser, Debora; Hattendorf, Bodo; Li, Zhongshu; Krumeich, Frank; Rosenthal, Amos; Rana, Vijay Kumar; Schönberg, Hartmut; Benkő, Zoltán; Grützmacher, Hansjörg

2018-05-16

Bismesitoylphosphinic acid, (HO)PO(COMes) 2 (BAPO-OH), is an efficient photoinitiator for free-radical polymerizations of olefins in aqueous phase. Described here are the structures of various copper(II) and copper(I) complexes with BAPO-OH as the ligand. The complex Cu II (BAPO-O) 2 (H 2 O) 2 is photoactive, and under irradiation with UV light in aqueous phase, it serves as a source of metallic copper in high purity and yield (>80 %). Simultaneously, the radical polymerization of acrylates can be initiated and allows the preparation of nanoparticle/polymer nanocomposites in which the metallic Cu nanoparticles are protected against oxidation. The determination of the stoichiometry of the photoreductions suggests an almost quantitative conversion from Cu II into Cu 0 with half an equivalent of BAPO-OH, which serves as a four-electron photoreductant. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Intralesional copper wire retention and pingyangmycin injection: an effective combinational therapy for complex venous malformation in soft tissue.

PubMed

Yuan, S-M; Hong, Z-J; Jiang, H-Q; Wang, J; Hu, X-B

2014-04-01

Complex venous malformations (VMs) may extensively involve the soft tissue. The treatment remains a challenge till now. Here we introduce a combinational therapy of copper wires and pingyangmycin (bleomycin A5,PYM). Copper wires were retained in VMs by repeated penetration with a straight needle. Subsequently, PYM solution was injected into the lesion. Eight to 10 days later, copper wires were removed. The dressing was changed every day until the puncture pores healed. Magnetic resonance imaging scanning was performed to observe the change of VMs. From January 2001 to December 2011, 56 patients were treated. During the follow-up period, most of the VMs shrunk obviously. The symptoms were relieved or disappeared. The complications included local pain, temporary paraesthesia and moderate fever, which disappeared quickly after the removal of copper wires. This combinational therapy is a safe and effective approach for the complex VMs in soft tissue.

Structure and spectroscopic properties of the dimeric copper(I) N-heterocyclic carbene complex [Cu₂(CNC(t-Bu))₂](PF₆)₂.

PubMed

Riener, Korbinian; Pöthig, Alexander; Cokoja, Mirza; Herrmann, Wolfgang A; Kühn, Fritz E

2015-08-01

In recent years, the use of copper N-heterocyclic carbene (NHC) complexes has expanded to fields besides catalysis, namely medicinal chemistry and luminescence applications. In the latter case, multinuclear copper NHC compounds have attracted interest, however, the number of these complexes in the literature is still quite limited. Bis[μ-1,3-bis(3-tert-butylimidazolin-2-yliden-1-yl)pyridine]-1κ(4)C(2),N:N,C(2');2κ(4)C(2),N:N,C(2')-dicopper(I) bis(hexafluoridophosphate), [Cu2(C19H25N5)2](PF6)2, is a dimeric copper(I) complex bridged by two CNC, i.e. bis(N-heterocyclic carbene)pyridine, ligands. Each Cu(I) atom is almost linearly coordinated by two NHC ligands and interactions are observed between the pyridine N atoms and the metal centres, while no cuprophilic interactions were observed. Very strong absorption bands are evident in the UV-Vis spectrum at 236 and 274 nm, and an emission band is observed at 450 nm. The reported complex is a new example of a multinuclear copper NHC complex and a member of a compound class which has only rarely been reported.

Physicochemical, antioxidant, DNA cleaving properties and antimicrobial activity of fisetin-copper chelates.

PubMed

Łodyga-Chruscińska, Elżbieta; Pilo, Maria; Zucca, Antonio; Garribba, Eugenio; Klewicka, Elżbieta; Rowińska-Żyrek, Magdalena; Symonowicz, Marzena; Chrusciński, Longin; Cheshchevik, Vitalij T

2018-03-01

Fisetin (3,3',4',7-tetrahydroxyflavone) metal chelates are of interest as this plant polyphenol has revealed broad prospects for its use as natural medicine in the treatment of various diseases. Metal interactions may change or enhance fisetin biological properties so understanding fisetin metal chelation is important for its application not only in medicine but also as a food additive in nutritional supplements. This work was aimed to determine and characterize copper complexes formed in different pH range at applying various metal/ligand ratios. Fisetin and Cu(II)-fisetin complexes were characterized by potentiometric titrations, UV-Vis (Ultraviolet-visible spectroscopy), EPR, ESI-MS, FTIR and cyclic voltammetry. Their effects on DNA were investigated by using circular dichroism, spectrofluorimetry and gel electrophoresis methods. The copper complex with the ratio of Cu(II)/fisetin 1/2 exhibited significant DNA cleavage activity, followed by complete degradation of DNA. The influence of copper(II) ions on antioxidant activity of fisetin in vitro has been studied using DPPH, ABTS and mitochondrial assays. The results have pointed out that fisetin or copper complexes can behave both as antioxidants or pro-oxidants. Antimicrobial activity of the compounds has been investigated towards several bacteria and fungi. The copper complex of Cu(II)/fisetin 1/2 ratio showed higher antagonistic activity against bacteria comparing to the ligand and it revealed a promising antifungal activity. Copyright © 2017 Elsevier Inc. All rights reserved.

Copper mercaptides as sulfur dioxide indicators

DOEpatents

Eller, Phillip G.; Kubas, Gregory J.

1979-01-01

Organophosphine copper(I) mercaptide complexes are useful as convenient and semiquantitative visual sulfur dioxide gas indicators. The air-stable complexes form 1:1 adducts in the presence of low concentrations of sulfur dioxide gas, with an associated color change from nearly colorless to yellow-orange. The mercaptides are made by mixing stoichiometric amounts of the appropriate copper(I) mercaptide and phosphine in an inert organic solvent.

Topical Treatment With Liposomal Sodium Copper Chlorophyllin Complex in Subjects With Facial Redness and Erythematotelangiectatic Rosacea: Case Studies.

PubMed

Vasily, David B

2015-10-01

Physicians are often presented with patients complaining of facial redness and difficult to control rosacea. The water soluble sodium copper chlorophyllin complex has been shown to have anti-oxidant, anti-inflammatory, and anti-bacterial activities in vitro and anti-redness, pore reduction, and anti-acne activities in pilot clinical studies. In these case studies, the safety and efficacy of a topical gel containing a liposomal suspension of sodium copper chlorophyllin complex was assessed in subjects with facial redness and erythematotelangiectatic rosacea.

Copper Recovery from Yulong Complex Copper Oxide Ore by Flotation and Magnetic Separation

NASA Astrophysics Data System (ADS)

Han, Junwei; Xiao, Jun; Qin, Wenqing; Chen, Daixiong; Liu, Wei

2017-09-01

A combined process of flotation and high-gradient magnetic separation was proposed to utilize Yulong complex copper oxide ore. The effects of particle size, activators, Na2S dosage, LA (a mixture of ammonium sulfate and ethylenediamine) dosage, activating time, collectors, COC (a combination collector of modified hydroxyl oxime acid and xanthate) dosage, and magnetic intensity on the copper recovery were investigated. The results showed that 74.08% Cu was recovered by flotation, while the average grade of the copper concentrates was 21.68%. Another 17.34% Cu was further recovered from the flotation tailing by magnetic separation at 0.8 T. The cumulative recovery of copper reached 91.42%. The modifier LA played a positive role in facilitating the sulfidation of copper oxide with Na2S, and the combined collector COC was better than other collectors for the copper flotation. This technology has been successfully applied to industrial production, and the results are consistent with the laboratory data.

Metallosupramolecular Architectures Obtained from Poly-N-heterocyclic Carbene Ligands.

PubMed

Sinha, Narayan; Hahn, F Ekkehardt

2017-09-19

Over the past two decades, self-assembly of supramolecular architectures has become a field of intensive research due to the wide range of applications for the resulting assemblies in various fields such as molecular encapsulation, supramolecular catalysis, drug delivery, metallopharmaceuticals, chemical and photochemical sensing, and light-emitting materials. For these purposes, a large number of coordination-driven metallacycles and metallacages featuring different sizes and shapes have been prepared and investigated. Almost all of these are Werner-type coordination compounds where metal centers are coordinated by nitrogen and/or oxygen donors of polydentate ligands. With the evolving interest in the coordination chemistry of N-heterocyclic carbenes (NHCs), discrete supramolecular complexes held together by M-C NHC bonds have recently become of interest. The construction of such metallosupramolecular assemblies requires the synthesis of suitable poly-NHC ligands where the NHC donors form labile bonds with metal centers thus enabling the formation of the thermodynamically most stable reaction product. In organometallic chemistry, these conditions are uniquely met by the combination of poly-NHCs and silver(I) ions where the resulting assemblies also offer the possibility to generate new structures by transmetalation of the poly-NHC ligands to additional metal centers forming more stable C NHC -M bonds. Stable metallosupramolecular assemblies obtained from poly-NHC ligands feature special properties such as good solubility in many less polar organic solvents and the presence of the often catalyticlly active {M(NHC) n } moiety as building block. In this Account, we review recent developments in organometallic supramolecular architectures derived from poly-NHC ligands. We describe dinuclear (M = Ag I , Au I , Cu I ) tetracarbene complexes obtained from bis-NHC ligands with an internal olefin or two external coumarin pendants and their postsynthetic modification via a photochemically induced single or double [2 + 2] cycloaddition to form dinuclear tetracarbene complexes featuring cyclobutane units. Even three-dimensional cage-like structures can be prepared by this postsynthetic strategy. Cylinder-like trinuclear, tetranuclear, and hexanuclear (M = Ag I , Au I , Cu I , Hg II , Pd II ) complexes have been obtained from benzene-bridged tris-, tetrakis-, or hexakis-NHC ligands. These complexes resemble polynuclear assemblies obtained from related polydentate Werner-type ligands. Contrary to the Werner-type complexes, cylinder-like assemblies with three, four, or six silver(I) ions sandwiched in between two tris-, tetrakis-, or hexakis-NHC ligands undergo a facile transmetalation reaction to give the complexes featuring more stable M-C NHC bonds, normally with retention of the metallosupramolecular structure. This unique behavior of NHC-Ag + complexes allows the prepration of assemblies containing various metals from the poly-NHC silver(I) assemblies. Narcissistic self-sorting phenomena have also been observed for mixtures of selected poly-NHC ligands and silver(I) ions. Even a very early type of metallosupramolecular assembly, the tetranuclear molecular square, can be prepared from four bridging dicarbene ligands and four transition metal ions either by a stepwise assembly or by a single-step protocol. At this point, it appears that procedures for the synthesis of metallosupramolecular assemblies using polydentate Werner-type ligands and metal ions can be transferred to organometallic chemistry by using suitable poly-NHC ligands. The resulting structures feature stable M-C NHC bonds (with the exception of the labile C NHC -Ag + bond) when compared to M-N/M-O bonds in classical Werner-type complexes. The generally good solubility of the compounds and the presence of the often catalytically active {M(NHC) n } moiety make organometallic supramolecular complexes a promising new class of molecular hosts for catalytic transformations and encapsulation of selected substrates.

Nanoscale Reaction Vessels Designed for Synthesis of Copper-Drug Complexes Suitable for Preclinical Development

PubMed Central

Wehbe, Mohamed; Anantha, Malathi; Backstrom, Ian; Leung, Ada; Chen, Kent; Malhotra, Armaan; Edwards, Katarina; Bally, Marcel B.

2016-01-01

The development of copper-drug complexes (CDCs) is hindered due to their very poor aqueous solubility. Diethyldithiocarbamate (DDC) is the primary metabolite of disulfiram, an approved drug for alcoholism that is being repurposed for cancer. The anticancer activity of DDC is dependent on complexation with copper to form copper bis-diethyldithiocarbamate (Cu(DDC)2), a highly insoluble complex that has not been possible to develop for indications requiring parenteral administration. We have resolved this issue by synthesizing Cu(DDC)2 inside liposomes. DDC crosses the liposomal lipid bilayer, reacting with the entrapped copper; a reaction that can be observed through a colour change as the solution goes from a light blue to dark brown. This method is successfully applied to other CDCs including the anti-parasitic drug clioquinol, the natural product quercetin and the novel targeted agent CX-5461. Our method provides a simple, transformative solution enabling, for the first time, the development of CDCs as viable candidate anticancer drugs; drugs that would represent a brand new class of therapeutics for cancer patients. PMID:27055237

Nanoscale Reaction Vessels Designed for Synthesis of Copper-Drug Complexes Suitable for Preclinical Development.

PubMed

Wehbe, Mohamed; Anantha, Malathi; Backstrom, Ian; Leung, Ada; Chen, Kent; Malhotra, Armaan; Edwards, Katarina; Bally, Marcel B

2016-01-01

The development of copper-drug complexes (CDCs) is hindered due to their very poor aqueous solubility. Diethyldithiocarbamate (DDC) is the primary metabolite of disulfiram, an approved drug for alcoholism that is being repurposed for cancer. The anticancer activity of DDC is dependent on complexation with copper to form copper bis-diethyldithiocarbamate (Cu(DDC)2), a highly insoluble complex that has not been possible to develop for indications requiring parenteral administration. We have resolved this issue by synthesizing Cu(DDC)2 inside liposomes. DDC crosses the liposomal lipid bilayer, reacting with the entrapped copper; a reaction that can be observed through a colour change as the solution goes from a light blue to dark brown. This method is successfully applied to other CDCs including the anti-parasitic drug clioquinol, the natural product quercetin and the novel targeted agent CX-5461. Our method provides a simple, transformative solution enabling, for the first time, the development of CDCs as viable candidate anticancer drugs; drugs that would represent a brand new class of therapeutics for cancer patients.

An efficient, cost effective, sensing behaviour liquid-liquid extraction and spectrophotometric determination of copper(II) incorporated with 4-(4‧-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole: Analysis of food samples, leafy vegetables, fertilizers and environmental samples

NASA Astrophysics Data System (ADS)

Barache, Umesh B.; Shaikh, Abdul B.; Lokhande, Tukaram N.; Kamble, Ganesh S.; Anuse, Mansing A.; Gaikwad, Shashikant H.

2018-01-01

The aim of the present work is to develop an efficient, simple and selective moreover cost-effective method for the extractive spectrophotometric determination of copper(II) by using the Schiff base 4-(4‧-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole [CBIMMT]. This chromogenic reagent forms a yellow coloured complex with copper(II) in acetate buffer at pH 4.2. The copper(II) complex with ligand is instantly extracted into chloroform and shows a maximum absorbance at 414 nm which remains stable for > 48 h. The composition of extracted complex is found to be 1:2 [copper(II): reagent] which was ascertained using Job's method of continuous variation, mole ratio method and slope ratio method. Under optimal conditions, the copper(II) complex in chloroform adheres to Beer's law up to 17.5 μg mL- 1 of copper(II). The optimum concentration range obtained from Ringbom's plot is from 5 μg mL- 1 to 17.5 μg mL- 1. The molar absorptivity, Sandell's sensitivity and enrichment factor of the extracted copper(II) chelate are 0.33813 × 104 L mol- 1 cm- 1, 0.01996 μg cm- 2 and 2.49 respectively. In the extraction of copper(II), several affecting factors including the solution pH, ligand concentration, equilibrium time, effect of foreign ions are optimized. The interfering effects of various cations and anions were also studied and use of masking agents enhances the selectivity of the method. The chromogenic sulphur containing reagent, 4-(4‧-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole has been synthesized in a single step with high purity and yield. The synthesized reagent has been successfully applied first time for determination of copper(II). The reagent forms stable chelate with copper(II) in buffer medium instantly and quantitatively extracted in chloroform within a minute. The method is successfully applied for the determination of copper(II) in various synthetic mixtures, complexes, fertilizers, environmental samples such as food samples, leafy vegetables, and water samples. The results are compared with those obtained with a reference procedure. Good agreement was attained. All the obtained results are indicative of a convenient, fast method for the extraction and quantification of micro levels of copper(II) from various environmental matrices without use of sophisticated instrumentation and procedure. The method showed a relative standard deviation of 0.42%.

An efficient, cost effective, sensing behaviour liquid-liquid extraction and spectrophotometric determination of copper(II) incorporated with 4-(4'-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole: Analysis of food samples, leafy vegetables, fertilizers and environmental samples.

PubMed

Barache, Umesh B; Shaikh, Abdul B; Lokhande, Tukaram N; Kamble, Ganesh S; Anuse, Mansing A; Gaikwad, Shashikant H

2018-01-15

The aim of the present work is to develop an efficient, simple and selective moreover cost-effective method for the extractive spectrophotometric determination of copper(II) by using the Schiff base 4-(4'-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole [CBIMMT]. This chromogenic reagent forms a yellow coloured complex with copper(II) in acetate buffer at pH4.2. The copper(II) complex with ligand is instantly extracted into chloroform and shows a maximum absorbance at 414nm which remains stable for >48h. The composition of extracted complex is found to be 1:2 [copper(II): reagent] which was ascertained using Job's method of continuous variation, mole ratio method and slope ratio method. Under optimal conditions, the copper(II) complex in chloroform adheres to Beer's law up to 17.5μgmL -1 of copper(II). The optimum concentration range obtained from Ringbom's plot is from 5μgmL -1 to 17.5μgmL -1 . The molar absorptivity, Sandell's sensitivity and enrichment factor of the extracted copper(II) chelate are 0.33813×10 4 Lmol -1 cm -1 , 0.01996μgcm -2 and 2.49 respectively. In the extraction of copper(II), several affecting factors including the solution pH, ligand concentration, equilibrium time, effect of foreign ions are optimized. The interfering effects of various cations and anions were also studied and use of masking agents enhances the selectivity of the method. The chromogenic sulphur containing reagent, 4-(4'-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole has been synthesized in a single step with high purity and yield. The synthesized reagent has been successfully applied first time for determination of copper(II). The reagent forms stable chelate with copper(II) in buffer medium instantly and quantitatively extracted in chloroform within a minute. The method is successfully applied for the determination of copper(II) in various synthetic mixtures, complexes, fertilizers, environmental samples such as food samples, leafy vegetables, and water samples. The results are compared with those obtained with a reference procedure. Good agreement was attained. All the obtained results are indicative of a convenient, fast method for the extraction and quantification of micro levels of copper(II) from various environmental matrices without use of sophisticated instrumentation and procedure. The method showed a relative standard deviation of 0.42%. Copyright © 2017 Elsevier B.V. All rights reserved.

Interaction of polyethyleneimine-anchored copper(II) complexes with tRNA studied by spectroscopy methods and biological activities.

PubMed

Lakshmipraba, Jagadeesan; Arunachalam, Sankaralingam; Gandi, Devadas A; Thirunalasundari, Thyagarajan; Vignesh, Sivanandham; James, Rathinam A

2017-05-01

Ultraviolet-visible, emission and circular dichroism spectroscopic methods were used in transfer RNA (tRNA) interaction studies performed for polyethyleneimine-copper(II) complexes [Cu(phen)(l-Tyr)BPEI]ClO 4 (where phen =1,10-phenanthroline, l-Tyr = l-tyrosine and BPEI = branched polyethyleneimine) with various degrees of coordination (x = 0.059, 0.149, 0.182) in the polymer chain. The results indicated that polyethyleneimine-copper(II) complexes bind with tRNA mostly through surface binding, although other binding modes, such as hydrogen bonding and van der Waals interactions, might also be present. Dye-exclusion, sulforhodamine B and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays of a polyethyleneimine-copper(II) complex with a higher degree of coordination against different cancer cell lines proved that the complex exhibited cytotoxic specificity and a significant cancer cell inhibition rate. Antimicrobial screening showed activity against some human pathogens. Copyright © 2016 John Wiley & Sons, Ltd.

Vectorization of copper complexes via biocompatible and biodegradable PLGA nanoparticles.

PubMed

Courant, T; Roullin, V G; Cadiou, C; Delavoie, F; Molinari, M; Andry, M C; Gafa, V; Chuburu, F

2010-04-23

A double emulsion-solvent diffusion approach with fully biocompatible materials was used to encapsulate copper complexes within biodegradable nanoparticles, for which the release kinetics profiles have highlighted their potential use for a prolonged circulating administration.

Decontamination and Disposal Methods for Chemical Agents - A Literature Survey

DTIC Science & Technology

1982-11-01

aqueous copper (I) ammonia complex to give a red copper (1) acetylide precipitate. The precipitate was determined either iodometricaily (sensitivity of I...ppm in decontamination solution) or colorintrically by a copper (11) ammonia complex (12 ppm). Lewisite was also assayed by gas liquid chromatography...to ammonia (then degraded to nitrogen) and carbonate ion. The latter reaction is relatively slow. The reaction may thus be con- sidered to consist of

Biomimetic Modeling of Copper Complexes: A Study of Enantioselective Catalytic Oxidation on D-(+)-Catechin and L-( − )-Epicatechin with Copper Complexes

PubMed Central

Mutti, Francesco G.; Pievo, Roberta; Sgobba, Maila; Gullotti, Michele; Santagostini, Laura

2008-01-01

The biomimetic catalytic oxidations of the dinuclear and trinuclear copper(II) complexes versus two catechols, namely, D-(+)-catechin and L-( − )-epicatechin to give the corresponding quinones are reported. The unstable quinones were trapped by the nucleophilic reagent, 3-methyl-2-benzothiazolinone hydrazone (MBTH), and have been calculated the molar absorptivities of the different quinones. The catalytic efficiency is moderate, as inferred by kinetic constants, but the complexes exhibit significant enantio-differentiating ability towards the catechols, albeit for the dinuclear complexes, this enantio-differentiating ability is lower. In all cases, the preferred enantiomeric substrate is D-(+)-catechin to respect the other catechol, because of the spatial disposition of this substrate. PMID:18825268

Design of copper DNA intercalators with leishmanicidal activity.

PubMed

Navarro, Maribel; Cisneros-Fajardo, Efrén José; Sierralta, Aníbal; Fernández-Mestre, Mercedes; Silva, Pedro; Arrieche, Dwight; Marchán, Edgar

2003-04-01

The complexes [Cu(dppz)(NO(3))]NO(3) (1), [Cu(dppz)(2)(NO(3))]NO(3) (2), [Cu(dpq)(NO(3))]NO(3) (3), and [Cu(dpq)(2)(NO(3))]NO(3) (4) were synthesized and characterized by elemental analysis, FAB-mass spectrometry, EPR, UV, and IR spectroscopies, and molar conductivity. DNA interaction studies showed that intercalation is an important way of interacting with DNA for these complexes. The biological activity of these copper complexes was evaluated on Leishmania braziliensis promastigotes, and the results showed leishmanicidal activity. Preliminary ultrastructural studies with the most active complex (2) at 1 h revealed parasite swelling and binucleated cells. This finding suggests that the leishmanicidal activity of the copper complexes could be associated with their interaction with the parasitic DNA.

Role of the P-Type ATPases, ATP7A and ATP7B in brain copper homeostasis.

PubMed

Telianidis, Jonathon; Hung, Ya Hui; Materia, Stephanie; Fontaine, Sharon La

2013-01-01

Over the past two decades there have been significant advances in our understanding of copper homeostasis and the pathological consequences of copper dysregulation. Cumulative evidence is revealing a complex regulatory network of proteins and pathways that maintain copper homeostasis. The recognition of copper dysregulation as a key pathological feature in prominent neurodegenerative disorders such as Alzheimer's, Parkinson's, and prion diseases has led to increased research focus on the mechanisms controlling copper homeostasis in the brain. The copper-transporting P-type ATPases (copper-ATPases), ATP7A and ATP7B, are critical components of the copper regulatory network. Our understanding of the biochemistry and cell biology of these complex proteins has grown significantly since their discovery in 1993. They are large polytopic transmembrane proteins with six copper-binding motifs within the cytoplasmic N-terminal domain, eight transmembrane domains, and highly conserved catalytic domains. These proteins catalyze ATP-dependent copper transport across cell membranes for the metallation of many essential cuproenzymes, as well as for the removal of excess cellular copper to prevent copper toxicity. A key functional aspect of these copper transporters is their copper-responsive trafficking between the trans-Golgi network and the cell periphery. ATP7A- and ATP7B-deficiency, due to genetic mutation, underlie the inherited copper transport disorders, Menkes and Wilson diseases, respectively. Their importance in maintaining brain copper homeostasis is underscored by the severe neuropathological deficits in these disorders. Herein we will review and update our current knowledge of these copper transporters in the brain and the central nervous system, their distribution and regulation, their role in normal brain copper homeostasis, and how their absence or dysfunction contributes to disturbances in copper homeostasis and neurodegeneration.

Role of the P-Type ATPases, ATP7A and ATP7B in brain copper homeostasis

PubMed Central

Telianidis, Jonathon; Hung, Ya Hui; Materia, Stephanie; Fontaine, Sharon La

2013-01-01

Over the past two decades there have been significant advances in our understanding of copper homeostasis and the pathological consequences of copper dysregulation. Cumulative evidence is revealing a complex regulatory network of proteins and pathways that maintain copper homeostasis. The recognition of copper dysregulation as a key pathological feature in prominent neurodegenerative disorders such as Alzheimer’s, Parkinson’s, and prion diseases has led to increased research focus on the mechanisms controlling copper homeostasis in the brain. The copper-transporting P-type ATPases (copper-ATPases), ATP7A and ATP7B, are critical components of the copper regulatory network. Our understanding of the biochemistry and cell biology of these complex proteins has grown significantly since their discovery in 1993. They are large polytopic transmembrane proteins with six copper-binding motifs within the cytoplasmic N-terminal domain, eight transmembrane domains, and highly conserved catalytic domains. These proteins catalyze ATP-dependent copper transport across cell membranes for the metallation of many essential cuproenzymes, as well as for the removal of excess cellular copper to prevent copper toxicity. A key functional aspect of these copper transporters is their copper-responsive trafficking between the trans-Golgi network and the cell periphery. ATP7A- and ATP7B-deficiency, due to genetic mutation, underlie the inherited copper transport disorders, Menkes and Wilson diseases, respectively. Their importance in maintaining brain copper homeostasis is underscored by the severe neuropathological deficits in these disorders. Herein we will review and update our current knowledge of these copper transporters in the brain and the central nervous system, their distribution and regulation, their role in normal brain copper homeostasis, and how their absence or dysfunction contributes to disturbances in copper homeostasis and neurodegeneration. PMID:23986700

Effect of copper sulphate treatment on natural phytoplanktonic communities.

PubMed

Le Jeune, Anne-Hélène; Charpin, Marie; Deluchat, Véronique; Briand, Jean-François; Lenain, Jean-François; Baudu, Michel; Amblard, Christian

2006-12-01

Copper sulphate treatment is widely used as a global and empirical method to remove or control phytoplankton blooms without precise description of the impact on phytoplanktonic populations. The effects of two copper sulphate treatments on natural phytoplanktonic communities sampled in the spring and summer seasons, were assessed by indoor mesocosm experiments. The initial copper-complexing capacity of each water sample was evaluated before each treatment. The copper concentrations applied were 80 microg l(-1) and 160 microg l(-1) of copper, below and above the water complexation capacity, respectively. The phytoplanktonic biomass recovered within a few days after treatment. The highest copper concentration, which generated a highly toxic environment, caused a global decrease in phytoplankton diversity, and led to the development and dominance of nanophytoplanktonic Chlorophyceae. In mesocosms treated with 80 microg l(-1) of copper, the effect on phytoplanktonic community size-class structure and composition was dependent on seasonal variation. This could be related to differences in community composition, and thus to species sensitivity to copper and to differences in copper bioavailability between spring and summer. Both treatments significantly affected cyanobacterial biomass and caused changes in the size-class structure and composition of phytoplanktonic communities which may imply modifications of the ecosystem structure and function.

Chemical speciation and bioavailability of Cu(II). Study of the ionic copper(II) and bis(glycinate)-copper(II) accumulation by Lemna species

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benda, F.; Kouba, J.

1991-03-01

In this paper, the authors examined the accumulation of copper(II) in, and its toxic effect on, duckweed, a plant which exhibits extremely high concentration factors. The effect of copper(II) was investigated by adding it to the minimal medium in two forms: CuSO{sub 4} and (Cu(Gly){sub 2}). The neutral (2:1) tetracoordinated bis(glycinate)-copper(II) complex is constituted by two five-membered rings bonded to the central copper atom with the cis configuration. This complex was chosen to model the function of a neutral species (eliminating the charge effect) involving a nontoxic ligand, for which - in contrast to the hydrated Cu{sup 2+} species -more » direct permeation through the cell wall is conceivable.« less

Antimicrobial Activity and Urease Inhibition of Schiff Bases Derived from Isoniazid and Fluorinated Benzaldehydes and of Their Copper(II) Complexes.

PubMed

Habala, Ladislav; Varényi, Samuel; Bilková, Andrea; Herich, Peter; Valentová, Jindra; Kožíšek, Jozef; Devínsky, Ferdinand

2016-12-17

In order to evaluate the influence of substitution on biological properties of Schiff bases and their metal complexes, a series of differently substituted fluorine-containing Schiff bases starting from the drug isoniazid (isonicotinylhydrazide) were prepared and their structures were established by single-crystal X-ray diffraction. Also, four copper(II) complexes of these Schiff bases were synthesized. The prepared compounds were evaluated for their antimicrobial activity and urease inhibition. Two of the Schiff bases exerted activity against C. albicans . All copper(II) complexes showed excellent inhibitory properties against jack bean urease, considerably better than that of the standard inhibitor acetohydroxamic acid.

Hydrothermal growth of cross-linked hyperbranched copper dendrites using copper oxalate complex

NASA Astrophysics Data System (ADS)

Truong, Quang Duc; Kakihana, Masato

2012-06-01

A facile and surfactant-free approach has been developed for the synthesis of cross-linked hyperbranched copper dendrites using copper oxalate complex as a precursor and oxalic acid as a reducing and structure-directing agent. The synthesized particles are composed of highly branched nanostructures with unusual cross-linked hierarchical networks. The formation of copper dendrites can be explained in view of both diffusion control and aggregation-based growth model accompanied by the chelation-assisted assembly. Oxalic acid was found to play dual roles as reducing and structure-directing agent based on the investigation results. The understanding on the crystal growth and the roles of oxalic acid provides clear insight into the formation mechanism of hyperbranched metal dendrites.

Surface Structures Formed by a Copper(II) Complex of Alkyl-Derivatized Indigo

PubMed Central

Honda, Akinori; Noda, Keisuke; Tamaki, Yoshinori; Miyamura, Kazuo

2016-01-01

Assembled structures of dyes have great influence on their coloring function. For example, metal ions added in the dyeing process are known to prevent fading of color. Thus, we have investigated the influence of an addition of copper(II) ion on the surface structure of alkyl-derivatized indigo. Scanning tunneling microscope (STM) analysis revealed that the copper(II) complexes of indigo formed orderly lamellar structures on a HOPG substrate. These lamellar structures of the complexes are found to be more stable than those of alkyl-derivatized indigos alone. Furthermore, 2D chirality was observed. PMID:28773957

Phosphate effects on copper(II) and lead(II) sorption to ferrihydrite

NASA Astrophysics Data System (ADS)

Tiberg, Charlotta; Sjöstedt, Carin; Persson, Ingmar; Gustafsson, Jon Petter

2013-11-01

Transport of lead(II) and copper(II) ions in soil is affected by the soil phosphorus status. Part of the explanation may be that phosphate increases the adsorption of copper(II) and lead(II) to iron (hydr)oxides in soil, but the details of these interactions are poorly known. Knowledge about such mechanisms is important, for example, in risk assessments of contaminated sites and development of remediation methods. We used a combination of batch experiments, extended X-ray absorption fine structure (EXAFS) spectroscopy and surface complexation modeling with the three-plane CD-MUSIC model to study the effect of phosphate on sorption of copper(II) and lead(II) to ferrihydrite. The aim was to identify the surface complexes formed and to derive constants for the surface complexation reactions. In the batch experiments phosphate greatly enhanced the adsorption of copper(II) and lead(II) to ferrihydrite at pH < 6. The largest effects were seen for lead(II).

Structural diversity of three Cu(II) compounds based on a new tripodal zwitterionic ligand: Syntheses, structures and properties

NASA Astrophysics Data System (ADS)

Zhou, Jie; Zhao, Jing-Song; Feng, Jing; Zhang, Xiao-Feng; Xu, Jian; Du, Lin; Xie, Ming-Jin; Zhao, Qi-Hua

2018-03-01

An exploration of reactions of 1,1‧,1″-(benzene-1,3,5-triyltris(methylene))tris(4-carboxypyridinium)-tribromide (H3LBr3) with Cu(II) salt under different pH conditions has led to the formation of three complexes, [Cu(HL)2(H2O)3]·4(ClO4)·3H2O (1), [Cu2(HL)(μ3-OH)(μ2-H2O)(H2O)2]·4(ClO4)·6H2O (2), and [Cu3(L)2Cl6(H2O)4]·4H2O (3). Single-crystal X-ray analyses revealed that complex 1 displays a discrete mononuclear structure with the ligand in a bowl-shaped configuration. Complex 2 possesses a tetranuclear 1D beaded chain structure. While complex 3 features a discrete trinuclear 'H-type' structure with the ligand in a chair-like configuration. The distinct compositions and structures of 1-3 are mainly ascribed to the different pH values of the reaction solution, the influences of anions, as well as the configurations which the zwitterion ligands adopt. The magnetic properties of 2, and the photoluminescence properties of 2, and 3 have been investigated. Moreover, powder X-ray diffraction, infrared spectroscopy, and elemental analysis were also performed.

Electrochemical Water Oxidation and Stereoselective Oxygen Atom Transfer Mediated by a Copper Complex.

PubMed

Kafentzi, Maria-Chrysanthi; Papadakis, Raffaello; Gennarini, Federica; Kochem, Amélie; Iranzo, Olga; Le Mest, Yves; Le Poul, Nicolas; Tron, Thierry; Faure, Bruno; Simaan, A Jalila; Réglier, Marius

2018-04-06

Water oxidation by copper-based complexes to form dioxygen has attracted attention in recent years, with the aim of developing efficient and cheap catalysts for chemical energy storage. In addition, high-valent metal-oxo species produced by the oxidation of metal complexes in the presence of water can be used to achieve substrate oxygenation with the use of H 2 O as an oxygen source. To date, this strategy has not been reported for copper complexes. Herein, a copper(II) complex, [(RPY2)Cu(OTf) 2 ] (RPY2=N-substituted bis[2-pyridyl(ethylamine)] ligands; R=indane; OTf=triflate), is used. This complex, which contains an oxidizable substrate moiety (indane), is used as a tool to monitor an intramolecular oxygen atom transfer reaction. Electrochemical properties were investigated and, upon electrolysis at 1.30 V versus a normal hydrogen electrode (NHE), both dioxygen production and oxygenation of the indane moiety were observed. The ligand was oxidized in a highly diastereoselective manner, which indicated that the observed reactivity was mediated by metal-centered reactive species. The pH dependence of the reactivity was monitored and correlated with speciation deduced from different techniques, ranging from potentiometric titrations to spectroscopic studies and DFT calculations. Water oxidation for dioxygen production occurs at neutral pH and is probably mediated by the oxidation of a mononuclear copper(II) precursor. It is achieved with a rather low overpotential (280 mV at pH 7), although with limited efficiency. On the other hand, oxygenation is maximum at pH 8-8.5 and is probably mediated by the electrochemical oxidation of an antiferromagnetically coupled dinuclear bis(μ-hydroxo) copper(II) precursor. This constitutes the first example of copper-centered oxidative water activation for a selective oxygenation reaction. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis, crystal structure and spectroscopic and electrochemical properties of bridged trisbenzoato copper-zinc heterobinuclear complex of 2,2‧-bipyridine

NASA Astrophysics Data System (ADS)

Koch, Angira; Kumar, Arvind; Singh, Suryabhan; Borthakur, Rosmita; Basumatary, Debajani; Lal, Ram A.; Shangpung, Sankey

2015-03-01

The synthesis of the heterobinuclear copper-zinc complex [CuZn(bz)3(bpy)2]ClO4 (bz = benzoate) from benzoic acid and bipyridine is described. Single crystal X-ray diffraction studies of the heterobinuclear complex reveals the geometry of the benzoato bridged Cu(II)-Zn(II) centre. The copper or zinc atom is pentacoordinate, with two oxygen atoms from bridging benzoato groups and two nitrogen atoms from one bipyridine forming an approximate plane and a bridging oxygen atom from a monodentate benzoate group. The Cu-Zn distance is 3.345 Å. The complex is normal paramagnetic having μeff value equal to 1.75 BM, ruling out the possibility of Cu-Cu interaction in the structural unit. The ESR spectrum of the complex in CH3CN at RT exhibit an isotropic four line spectrum centred at g = 2.142 and hyperfine coupling constants Aav = 63 × 10-4 cm-1, characteristic of a mononuclear square-pyramidal copper(II) complexes. At LNT, the complex shows an isotropic spectrum with g|| = 2.254 and g⊥ = 2.071 and A|| = 160 × 10-4 cm-1. The Hamiltonian parameters are characteristic of distorted square pyramidal geometry. Cyclic voltammetric studies of the complex have indicated quasi-reversible behaviour in acetonitrile solution.

COPPER COMPLEXATION BY NATURAL ORGANIC MATTER IN CONTAMINATED AND UNCOMTAINATED GROUND WATER

EPA Science Inventory

Ground-water samples were collected from an uncontaminated and a contaminated site. Copper complexation was characterized by ion-selective electrode (ISE), fluorescence quenching (FQ), and cathodic stripping voltammetric (CSV) titrations. All of the samples were titrated at their...

Activation of dioxygen by copper metalloproteins and insights from model complexes

PubMed Central

Quist, David A.; Diaz, Daniel E.; Liu, Jeffrey J.; Karlin, Kenneth D.

2017-01-01

Nature uses dioxygen as a key oxidant in the transformation of biomolecules. Among the enzymes that are utilized for these reactions are copper-containing met-alloenzymes, which are responsible for important biological functions such as the regulation of neurotransmitters, dioxygen transport, and cellular respiration. Enzymatic and model system studies work in tandem in order to gain an understanding of the fundamental reductive activation of dioxygen by copper complexes. This review covers the most recent advancements in the structures, spectroscopy, and reaction mechanisms for dioxygen-activating copper proteins and relevant synthetic models thereof. An emphasis has also been placed on cofactor biogenesis, a fundamentally important process whereby biomolecules are post-translationally modified by the pro-enzyme active site to generate cofactors which are essential for the catalytic enzymatic reaction. Significant questions remaining in copper-ion-mediated O2-activation in copper proteins are addressed. PMID:27921179

Activation of dioxygen by copper metalloproteins and insights from model complexes.

PubMed

Quist, David A; Diaz, Daniel E; Liu, Jeffrey J; Karlin, Kenneth D

2017-04-01

Nature uses dioxygen as a key oxidant in the transformation of biomolecules. Among the enzymes that are utilized for these reactions are copper-containing metalloenzymes, which are responsible for important biological functions such as the regulation of neurotransmitters, dioxygen transport, and cellular respiration. Enzymatic and model system studies work in tandem in order to gain an understanding of the fundamental reductive activation of dioxygen by copper complexes. This review covers the most recent advancements in the structures, spectroscopy, and reaction mechanisms for dioxygen-activating copper proteins and relevant synthetic models thereof. An emphasis has also been placed on cofactor biogenesis, a fundamentally important process whereby biomolecules are post-translationally modified by the pro-enzyme active site to generate cofactors which are essential for the catalytic enzymatic reaction. Significant questions remaining in copper-ion-mediated O 2 -activation in copper proteins are addressed.

Synthesis, characterization, electrical conductivity and luminescence properties of two copper(II) complexes with tridentate N2O chelating ligands containing imine bond

NASA Astrophysics Data System (ADS)

Gönül, İlyas; Ay, Burak; Karaca, Serkan; Şahin, Onur; Serin, Selahattin

2018-03-01

In the present study, we describe the synthesis and characterization of two tridentate N2O donor ligands, namely, (E)-2-(((2-(diethylamino)ethyl)imino)methyl)-6-methoxyphenol (HL1) and (E)-2-(((2-(diethylamino)ethyl)imino)methyl)-6-ethoxyphenol (HL2), and their copper(II) complexes, [Cu(L1)(CH3COO)] (1), [Cu(L2)(CH3COO)] (2). They have been synthesized under conventional methods and characterized by elemental analysis, FTIR, 1H and 13C NMR, ICP-OES, TGA and GC/MS analysis. For the morphological analysis field emission scanning electron microscopy (FESEM) was used. The geometry of the copper(II) complexes was determined by single crystal X-ray diffraction analysis. The copper(II) ions are in distorted square-pyramidal coordination environments. Complexes crystallize in monoclinic space group, P21/c. The electrical conductivity and luminescence properties of 1-2 have been investigated.

Differential affinity of BsSCO for Cu(II) and Cu(I) suggests a redox role in copper transfer to the Cu(A) center of cytochrome c oxidase.

PubMed

Hill, Bruce C; Andrews, Diann

2012-06-01

SCO (synthesis of cytochrome c oxidase) proteins are involved in the assembly of the respiratory chain enzyme cytochrome c oxidase acting to assist in the assembly of the Cu(A) center contained within subunit II of the oxidase complex. The Cu(A) center receives electrons from the reductive substrate ferrocytochrome c, and passes them on to the cytochrome a center. Cytochrome a feeds electrons to the oxygen reaction site composed of cytochrome a(3) and Cu(B). Cu(A) consists of two copper ions positioned within bonding distance and ligated by two histidine side chains, one methionine, a backbone carbonyl and two bridging cysteine residues. The complex structure and redox capacity of Cu(A) present a potential assembly challenge. SCO proteins are members of the thioredoxin family which led to the early suggestion of a disulfide exchange function for SCO in Cu(A) assembly, whereas the copper binding capacity of the Bacillus subtilis version of SCO (i.e., BsSCO) suggests a direct role for SCO proteins in copper transfer. We have characterized redox and copper exchange properties of apo- and metalated-BsSCO. The release of copper (II) from its complex with BsSCO is best achieved by reducing it to Cu(I). We propose a mechanism involving both disulfide and copper exchange between BsSCO and the apo-Cu(A) site. This article is part of a Special Issue entitled: Biogenesis/Assembly of Respiratory Enzyme Complexes. Copyright © 2011 Elsevier B.V. All rights reserved.

Chitosan-Copper (II) complex as antibacterial agent: synthesis, characterization and coordinating bond- activity correlation study

NASA Astrophysics Data System (ADS)

Mekahlia, S.; Bouzid, B.

2009-11-01

The antimicrobial activity of chitosan is unstable and sensitive to many factors such as molecular weight. Recent investigations showed that low molecular weight chitosan exhibited strong bactericidal activities compared to chitosan with high molecular weight. Since chitosan degradation can be caused by the coordinating bond, we attempt to synthesize and characterize the chitosan-Cu (II) complex, and thereafter study the coordinating bond effect on its antibacterial activity against Salmonella enteritidis. Seven chitosan-copper complexes with different copper contents were prepared and characterized by FT-IR, UV-vis, XRD and atomic absorption spectrophotometry (AAS). Results indicated that for chitosan-Cu (II) complexes with molar ratio close to 1:1, the inhibition rate reached 100%.

Copper speciation in the gill microenvironment of carp (Cyprinus carpio) at various levels of pH.

PubMed

Tao, Shu; Long, Aimin; Xu, Fuliu; Dawson, R W

2002-07-01

The fish gill microenvironment of Cyprinus carpio under stress of copper exposure was investigated. pH and other parameters including free copper activity, alkalinity, and inorganic and organic carbons in the surrounding water (inspired water) and in the gill microenvironment (expired water) were measured or calculated at various levels of pH and varying total copper concentrations. The chemical equilibrium calculation (from MINEQA2) and complexation modeling (mucus-copper) were coupled to calculate both species distribution. The results indicate that the pH in the fish gill microenvironment was different from that in the surrounding water with a balance point around 6.9. The secretion of both CO(2) and mucus was affected in both linear and nonlinear ways when the fish were exposed to elevated concentrations of copper. The complexation capacity of the gill mucus was characterized by a conditional stability constant (logk(Cu-mucus)) of 5.37 along with a complexation equivalent concentration (L(Cu-mucus)) of 0.96 mmol Cu/mg C. For both the fish microenvironment and the surrounding water, the dominant copper species shifted from Cu(2+) to CuCO(3)(0) and to Cu(OH)(2)(0) when the pH of the surrounding water changed from 6.12 to 8.11. The change in copper speciation in the gill microenvironment is smaller than that in the surrounding water due to the pH buffering capacity of the fish gills.

Synthesis, characterization, antibacterial activity, SOD mimic and interaction with DNA of drug based copper(II) complexes

NASA Astrophysics Data System (ADS)

Patel, Mohan N.; Dosi, Promise A.; Bhatt, Bhupesh S.; Thakkar, Vasudev R.

2011-02-01

Novel metal complexes of the second-generation quinolone antibacterial agent enrofloxacin with copper(II) and neutral bidentate ligands have been prepared and characterized with elemental analysis reflectance, IR and mass spectroscopy. Complexes have been screened for their in-vitro antibacterial activity against two Gram (+ve)Staphylococcus aureus, Bacillus subtilis, and three Gram (-ve)Serratia marcescens, Escherichia coli and Pseudomonas aeruginosa organisms using the double dilution technique. The binding of this complex with CT-DNA has been investigated by absorption titration, salt effect and viscosity measurements. Binding constant is ranging from 1.3 × 10 4-3.7 × 10 4. The cleavage ability of complexes has been assessed by gel electrophoresis using pUC19 DNA. The catalytic activity of the copper(II) complexes towards the superoxide anion (O 2rad -) dismutation was assayed by their ability to inhibit the reduction of nitroblue tetrazolium (NBT).

New Approach to Remove Metals from Chromated Copper Arsenate (CCA)-Treated Wood

Treesearch

Todd F. Shupe; Chung Y. Hse; Hui Pan

2012-01-01

Recovery of metals from chromated copper arsenate (CCA)-treated southern pine wood particles was investigated using binary acid solutions consisting of acetic, oxalic, and phosphoric acids in a microwave reactor. Formation of an insoluble copper oxalate complex in the binary solution containing oxalic acid was the major factor for low copper removal. Furthermore, the...

GOLGI IN COPPER HOMEOSTASIS: A VIEW FROM THE MEMBRANE TRAFFICKING FIELD

PubMed Central

Polishchuk, Roman; Lutsenko, Svetlana

2013-01-01

Copper is essential for a variety of important biological processes as a cofactor and regulator of many enzymes. Incorporation of copper into the secreted and plasma membrane-targeted cuproenzymes takes place in Golgi, a compartment central for normal copper homeostasis. The Golgi complex harbors copper-transporting ATPases, ATP7A and ATP7B, that transfer copper from the cytosol into Golgi lumen for incorporation into copper-dependent enzymes. The Golgi complex also sends these ATPases to appropriate post-Golgi destinations to ensure correct Cu fluxes in the body and to avoid potentially toxic copper accumulation. Mutations in ATP7A or ATP7B or in the proteins that regulate their trafficking affect their exit from Golgi or subsequent retrieval to this organelle. This, in turn, disrupts the homeostatic Cu balance, resulting in copper deficiency (Menkes disease) or copper overload (Wilson disease). Research over the last decade has yielded significant insights into the enzymatic properties and cell biology of the copper-ATPases. However, the mechanisms through which the Golgi regulates trafficking of ATP7A/7B and, therefore, maintain Cu homeostasis remain unclear. This review summarizes current data on the role of the Golgi in Cu metabolism and outlines questions and challenges that should be addressed to understand ATP7A and ATP7B trafficking mechanisms in health and disease. PMID:23846821

Biotin Decorated Gold Nanoparticles for Targeted Delivery of a Smart-Linked Anticancer Active Copper Complex: In Vitro and In Vivo Studies.

PubMed

Pramanik, Anup K; Siddikuzzaman; Palanimuthu, Duraippandi; Somasundaram, Kumaravel; Samuelson, Ashoka G

2016-12-21

The synthesis and anticancer activity of a copper(II) diacetyl-bis(N4-methylthiosemicarbazone) complex and its nanoconjugates are reported. The copper(II) complex is connected to a carboxylic acid group through a cleavable disulfide link to enable smart delivery. The copper complex is tethered to highly water-soluble 20 nm gold nanoparticles (AuNPs), stabilized by amine terminated lipoic acid-polyethylene glycol (PEG). The gold nanoparticle carrier was further decorated with biotin to achieve targeted action. The copper complex and the conjugates with and without biotin, were tested against HeLa and HaCaT cells. They show very good anticancer activity against HeLa cells, a cell line derived from cervical cancer and are less active against HaCaT cells. Slow and sustained release of the complex from conjugates is demonstrated through cleavage of disulfide linker in the presence of glutathione (GSH), a reducing agent intrinsically present in high concentrations within cancer cells. Biotin appended conjugates do not show greater activity than conjugates without biotin against HeLa cells. This is consistent with drug uptake studies, which suggests similar uptake profiles for both conjugates in vitro. However, in vivo studies using a HeLa cell xenograft tumor model shows 3.8-fold reduction in tumor volume for the biotin conjugated nanoparticle compared to the control whereas the conjugate without biotin shows only 2.3-fold reduction in the tumor volume suggesting significant targeting.

Synthesis, spectral characterization and structural studies of a novel O, N, O donor semicarbazone and its binuclear copper complex with hydrogen bond stabilized lattice

NASA Astrophysics Data System (ADS)

Layana, S. R.; Saritha, S. R.; Anitha, L.; Sithambaresan, M.; Sudarsanakumar, M. R.; Suma, S.

2018-04-01

A novel O,N,O donor salicylaldehyde-N4-phenylsemicarbazone, (H2L) has been synthesized and physicochemically characterized. Detailed structural studies of H2L using single crystal X-ray diffraction technique reveals the existence of intra and inter molecular hydrogen bonding interactions, which provide extra stability to the molecule. We have successfully synthesized a binuclear copper(II) complex, [Cu2(HL)2(NO3)(H2O)2]NO3 with phenoxy bridging between the two copper centers. The complex was characterized by elemental analysis, magnetic susceptibility and conductivity measurements, FT-IR, UV-Visible, mass and EPR spectral methods. The grown crystals of the copper complex were employed for the single crystal X-ray diffraction studies. The complex possesses geometrically different metal centers, in which the ligand coordinates through ketoamide oxygen, azomethine nitrogen and deprotonated phenoxy oxygen. The extensive intermolecular hydrogen bonding interactions of the coordinated and the lattice nitrate groups interconnect the complex units to form a 2D supramolecular assembly. The ESI mass spectrum substantiates the existence of 1:1 complex. The g values obtained from the EPR spectrum in frozen DMF suggest dx2 -y2 ground state for the unpaired electron.

Spectroscopic characterization, antioxidant and antitumour studies of novel bromo substituted thiosemicarbazone and its copper(II), nickel(II) and palladium(II) complexes

NASA Astrophysics Data System (ADS)

Jagadeesh, M.; Lavanya, M.; Kalangi, Suresh K.; Sarala, Y.; Ramachandraiah, C.; Varada Reddy, A.

2015-01-01

A new, slightly distorted octahedral complex of copper(II), square planar complexes of nickel(II) and palladium(II) with 2,4‧-dibromoacetophenone thiosemicarbazone (DBAPTSC) are synthesized. The ligand and the complexes are characterized by FT-IR, FT-Raman, powder X-ray diffraction studies. The IR and Raman data are correlated for the presence of the functional groups which specifically helped in the confirmation of the compounds. In addition, the free ligand is unambiguously characterized by 1H and 13C NMR spectroscopy while the copper(II) complex is characterized by electron paramagnetic resonance spectroscopy (EPR). The g values for the same are found to be 2.246 (g1), 2.012 (g2) and 2.005 (g3) which suggested rhombic distortions. The HOMO-LUMO band gap calculations for these compounds are found to be in between 0.5 and 4.0 eV and these compounds are identified as semiconducting materials. The synthesized ligand and its copper(II), nickel(II) and palladium(II) complexes are subjected to antitumour activity against the HepG2 human hepatoblastoma cell lines. Among all the compounds, nickel(II) complex is found to exert better antitumour activity with 57.6% of cytotoxicity.

Synthesis of isocoumarins through three-component couplings of arynes, terminal alkynes, and carbon dioxide catalyzed by an NHC-copper complex.

PubMed

Yoo, Woo-Jin; Nguyen, Thanh V Q; Kobayashi, Shū

2014-09-15

A copper-catalyzed multicomponent coupling reaction between in situ generated ortho-arynes, terminal alkynes, and carbon dioxide was developed to access isocoumarins in moderate to good yields. The key to this CO2-incorporating reaction was the use of a versatile N-heterocyclic carbene/copper complex that was able to catalyze multiple transformations within the three-component reaction. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

21 CFR 73.3110 - Chlorophyllin-copper complex, oil soluble.

Code of Federal Regulations, 2010 CFR

2010-04-01

... oil, peanut oil, and hydrogenated peanut oil), may be safely used to color polymethylmethacrylate bone... the bone cement. (2) Authorization for this use shall not be construed as waiving any of the... the polymethylmethacrylate bone cement in which chlorophyllin-copper complex, oil soluble, is used. (d...

21 CFR 73.3110 - Chlorophyllin-copper complex, oil soluble.

Code of Federal Regulations, 2013 CFR

2013-04-01

... oil, peanut oil, and hydrogenated peanut oil), may be safely used to color polymethylmethacrylate bone... the bone cement. (2) Authorization for this use shall not be construed as waiving any of the... the polymethylmethacrylate bone cement in which chlorophyllin-copper complex, oil soluble, is used. (d...

21 CFR 73.3110 - Chlorophyllin-copper complex, oil soluble.

Code of Federal Regulations, 2014 CFR

2014-04-01

... oil, peanut oil, and hydrogenated peanut oil), may be safely used to color polymethylmethacrylate bone... the bone cement. (2) Authorization for this use shall not be construed as waiving any of the... the polymethylmethacrylate bone cement in which chlorophyllin-copper complex, oil soluble, is used. (d...

21 CFR 73.3110 - Chlorophyllin-copper complex, oil soluble.

Code of Federal Regulations, 2012 CFR

2012-04-01

... oil, peanut oil, and hydrogenated peanut oil), may be safely used to color polymethylmethacrylate bone... the bone cement. (2) Authorization for this use shall not be construed as waiving any of the... the polymethylmethacrylate bone cement in which chlorophyllin-copper complex, oil soluble, is used. (d...

21 CFR 73.3110 - Chlorophyllin-copper complex, oil soluble.

Code of Federal Regulations, 2011 CFR

2011-04-01

... oil, peanut oil, and hydrogenated peanut oil), may be safely used to color polymethylmethacrylate bone... the bone cement. (2) Authorization for this use shall not be construed as waiving any of the... the polymethylmethacrylate bone cement in which chlorophyllin-copper complex, oil soluble, is used. (d...

Preparation of Some Novel Copper(I) Complexes and their Molar Conductances in Organic Solvents

NASA Astrophysics Data System (ADS)

Gill, Dip Singh; Rana, Dilbag

2009-04-01

Attempts have been made to prepare some novel copper(I) nitrate, sulfate, and perchlorate complexes. Molar conductances of these complexes have been measured in organic solvents like acetonitrile (AN), acetone (AC), methanol (MeOH), N,N-dimethylformamide (DMF), N,Ndimethylacetamide (DMA), and dimethylsulfoxide (DMSO) at 298 K. The molar conductance data have been analyzed to obtain limiting molar conductances (λ0) and ion association constants (KA) of the electrolytes. The results showed that all these complexes are strong electrolytes in all organic solvents. The limiting ionic molar conductances (λo± ) for various ions have been calculated using Bu4NBPh4 as reference electrolyte. The actual radii for copper(I) complex ions are very large and different in different solvents and indicate some solvation effects in each solvent system

cis-2,2'-Bipyrimidine-bridged polynuclear complex: a stairway-like mixed-valent {Fe(4)} cluster.

PubMed

Alborés, Pablo; Rentschler, Eva

2010-10-04

We report the first example of a polynuclear discrete coordination compound exhibiting only bpym bridges and containing a first-row d transition metal. A smooth self-assembly one-pot synthetic route, starting from simply FeCl(2) and FeCl(3) hydrates, allowed us to prepare a tetranuclear Fe(4) cluster with a stairway-like structure and the formula cis-{[(H(2)O)Cl(3)Fe(III)-μ(bpym)Fe(II)Cl(2)]}(2)-μ(bpym) (1) . All spectroscopic data suggest that complex 1 is a valence-localized mixed-valent Fe(II)-Fe(III) cluster with typical Mössbauer lines for both sites, which do not change with temperature. Reflectance spectroscopy did not allow one to distinguish an intervalence charge-transfer band. However, time-dependent density functional theory (DFT) calculations predict a weak high-energy Fe(II) → Fe(III) transition. Regarding the magnetic properties, the high-spin Fe(II) and Fe(III) ions interact in a weakly antiferromagnetic way with isotropic J constants of only a few wavenumbers as derived from direct-current susceptibility and magnetization data. Broken-symmetry DFT calculations support these observations.

a Moessbauer Effect and Fenske-Hall Molecular Orbital Study of the Electronic Properties of Organoiron Clusters.

NASA Astrophysics Data System (ADS)

Buhl, Margaret Linn

The electronic properties of trinuclear iron, tetranuclear iron butterfly, iron-cobalt, and iron-copper clusters have been studied experimentally at 78K by the Mossbauer effect and theoretically by Fenske-Hall molecular orbital calculations. The Mossbauer effect isomer shift is very sensitive to the differences in the iron s-electron densities in these clusters and, as expected, decreases as the sum of the iron 4s Mulliken population and the Clementi and Raimondi effective nuclear charge increases. The molecular orbital wave functions and the Mulliken atomic charges are used to calculate the electric field gradient at the metal nuclei and the iron Mossbauer effect quadrupole splittings. The valence contribution was found to be the major component of the electric field gradient in all the clusters studied. In general the calculated value of Delta E_ {Q} is larger than the observed value, as a result of neglect of the valence Sternheimer factor, R. The metal charge depends upon its electronegativity and upon the nature of its Lewis base ligands. The carbonyl ligand carbon charge becomes more positive as the metal electronegativity increases. The oxygen charge becomes more negative as the anionic cluster charge increases, and in so doing, yields the maximum anionic charge separation. The electronic properties of the terminal carbonyl ligands are similar to those of carbon monoxide, whereas the electronic properties of the bridging carbonyl ligands are similar to those of the carbonyl group found in aldehydes and ketones.

The impact of tertiary wastewater treatment on copper and zinc complexation.

PubMed

Constantino, C; Gardner, M; Comber, S D W; Scrimshaw, M D; Ellor, B

2015-01-01

Tightening quality standards for European waters has seen a move towards enhanced wastewater treatment technologies such as granulated organic carbon treatment and ozonation. Although these technologies are likely to be successful in degrading certain micro-organic contaminants, these may also destroy compounds which would otherwise complex and render metals significantly less toxic. This study examined the impact of enhanced tertiary treatment on the capacity of organic compounds within sewage effluents to complex copper and zinc. The data show that granulated organic carbon treatment removes a dissolved organic carbon (DOC) fraction that is unimportant to complexation such that no detrimental impact on complexation or metal bioavailability is likely to occur from this treatment type. High concentrations of ozone (>1 mg O3/mg DOC) are, however, likely to impact the complexation capacity for copper although this is unlikely to be important at the concentrations of copper typically found in effluent discharges or in rivers. Ozone treatment did not affect zinc complexation capacity. The complexation profiles of the sewage effluents show these to contain a category of non-humic ligand that appears unaffected by tertiary treatment and which displays a high affinity for zinc, suggesting these may substantially reduce the bioavailability of zinc in effluent discharges. The implication is that traditional metal bioavailability assessment approaches such as the biotic ligand model may overestimate zinc bioavailability in sewage effluents and effluent-impacted waters.

Copper thiobis(alkylphenols) and antioxidant compositions thereof

DOE Office of Scientific and Technical Information (OSTI.GOV)

Braid, M.

1980-09-30

Novel copper thiobis(alkylphenol-phenolate) complexes are effective antioxidant additives for various organic media such as oils of lubricating viscosity and plastics. Additionally these novel copper organo-sulfur compounds are highly useful as energy quenchers and antisludging agents in a variety of organic substrates.

Radiation induced deposition of copper nanoparticles inside the nanochannels of poly(acrylic acid)-grafted poly(ethylene terephthalate) track-etched membranes

NASA Astrophysics Data System (ADS)

Korolkov, Ilya V.; Güven, Olgun; Mashentseva, Anastassiya A.; Atıcı, Ayse Bakar; Gorin, Yevgeniy G.; Zdorovets, Maxim V.; Taltenov, Abzal A.

2017-01-01

Poly(ethylene terephthalate) PET, track-etched membranes (TeMs) with 400 nm average pore size were UV-grafted with poly(acrylic acid) (PAA) after oxidation of inner surfaces by H2O2/UV system. Carboxylate groups of grafted PAA chains were easily complexed with Cu2+ ions in aqueous solutions. These ions were converted into metallic copper nanoparticles (NPs) by radiation-induced reduction of copper ions in aqueous-alcohol solution by gamma rays in the dose range of 46-250 kGy. Copper ions chelating with -COOH groups of PAA chains grafted on PET TeMs form polymer-metal ion complex that prevent the formation of agglomerates during reduction of copper ions to metallic nanoparticles. The detailed analysis by X-Ray diffraction technique (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed the deposition of copper nanoparticles with the average size of 70 nm on the inner surface of nanochannels of PET TeMs. Samples were also investigated by FTIR, ESR spectroscopies to follow copper ion reduction.

Modular "Click" Preparation of Bifunctional Polymeric Heterometallic Catalysts.

PubMed

Wang, Wenlong; Zhao, Liyuan; Lv, Hui; Zhang, Guodong; Xia, Chungu; Hahn, F Ekkehardt; Li, Fuwei

2016-06-27

Heterobimetallic molecular complexes or strictly alternating metallated polymers are obtained by a click reaction between mononuclear metal complexes (secondary building units, SBUs) bearing NHCs functionalized with either p-azidophenyl or p-ethynylphenyl wingtips. With a copper-NHC complex as SBU the formation of molecular or polymeric compounds did not require any additives as the copper complex catalyzes the click reaction. Transmetallation from heterobimetallic Cu/Ag derivatives to Cu/Pd derivatives was achieved. The linker between the SBUs (flexible or rigid) influences the catalytic activity of the heterobimetallic compounds. The polymer with alternating copper-NHC and silver-NHC units and a flexible methylene-triazole bridge between them shows the highest activity in the catalytic alkynylation of trifluoromethyl ketones to give fluorinated propargylic alcohols. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis, structure, spectroscopic and electrochemical properties of (2-amino-4-methylpyrimidine)-(pyridine-2,6-dicarboxylato)copper(II) monohydrate

NASA Astrophysics Data System (ADS)

Uçar, İbrahim; Karabulut, Bünyamin; Bulut, Ahmet; Büyükgüngör, Orhan

2007-05-01

The (2-amino-4-methylpyrimidine)-(pyridine-2,6-dicarboxylato)copper(II) monohydrate complex was synthesized and characterized by spectroscopic (IR, UV/Vis, EPR), thermal (TG/DTA) and electrochemical methods. X-ray structural analysis of the title complex revealed that the copper ion can be considered to have two coordination spheres. In the first coordination sphere the copper ion forms distorted square-planar geometry with trans-N 2O 2 donor set, and also the metal ion is weakly bonded to the amino-nitrogen in the layer over and to the carboxylic oxygen in the layer underneath in the second coordination sphere. The second coordination environment on the copper ion is attributed to pseudo octahedron. The powder EPR spectra of Cu(II) complex at room and liquid nitrogen temperature were recorded. The calculated g and A parameters have indicated that the paramagnetic centre is axially symmetric. The molecular orbital bond coefficients of the Cu(II) ion in d 9 state is also calculated by using EPR and optical absorption parameters. The cyclic voltammogram of the title complex investigated in DMSO (dimethylsulfoxide) solution exhibits only metal centered electroactivity in the potential range -1.25 to 1.5 V versus Ag/AgCl reference electrode.

A heterobimetallic complex featuring a Ti–Co multiple bond and its application to the reductive coupling of ketones to alkenes† †Electronic supplementary information (ESI) available: Experimental procedures, additional spectroscopic data for 1–4, and computational details of 2 and 3. CCDC 1037714–1037716. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4sc03772c Click here for additional data file. Click here for additional data file.

PubMed Central

Wu, Bing; Bezpalko, Mark W.; Foxman, Bruce M.

2015-01-01

To explore metal–metal multiple bonds between first row transition metals, Ti/Co complexes supported by two phosphinoamide ligands have been synthesized and characterized. The Ti metalloligand Cl2Ti(XylNPiPr2)2 (1) was treated with CoI2 under reducing conditions, permitting isolation of the Ti/Co complex [(μ-Cl)Ti(XylNPiPr2)2CoI]2 (2). One electron reduction of complex 2 affords ClTi(XylNPiPr2)2CoPMe3 (3), which features a metal–metal triple bond and an unprecedentedly short Ti–Co distance of 2.0236(9) Å. This complex is shown to promote the McMurry coupling reaction of aryl ketones into alkenes, with concomitant formation of the tetranuclear complex [Ti(μ3-O)(NXylPiPr2)2CoI]2 (4). A cooperative mechanism involving bimetallic C 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 O bond activation and a cobalt carbene intermediate is proposed. PMID:29142672

Is copper chelation an effective anti-angiogenic strategy for cancer treatment?

PubMed

Antoniades, V; Sioga, A; Dietrich, E M; Meditskou, S; Ekonomou, L; Antoniades, K

2013-12-01

Angiogenesis and the acquisition of an angiogenic phenotype is important for cancer cell proliferation. Copper in an essential trace element that participates in many enzymatic complexes like the cytochrome c, superoxide dismutase and lysyl oxidase and it is involved in processes, like embryogenesis, growth, angiogenesis and carcinogenesis. In particular, its involvement in carcinogenesis was described for the first time in oral submucous fibrosis, where fibroblasts produce large amounts of collagen in the presence of copper. Copper's action in carcinogenesis is two-fold: (1) it participates in reactions with an increased redox potential that result in the production of oxidative products and oxidative stress. Through this mechanism, copper may cause DNA mutations in the nucleus and mitochondria or alterations to membrane phospholipids, (2) it participates in angiogenesis even in the absence of angiogenic molecules, as it was reported for the first time in rabbit cornea models with copolymer pellets charged with PGE1. Copper chelation regimens like penicillamine and tetrathiomolybdate are being described in the literature as having anti-angiogenic, anti-fibrotic and anti-inflammatory actions. Animal models of brain cancer that evaluated the anti-angiogenic properties of copper, have proven evidence of the reduction of tumor's microvascular supply, tumor volume and vascular permeability after plasma copper levels reduction. Interestingly, plasma copper levels reduction was shown to suppress micrometastases generation in mice models of breast cancer. We hypothesize that copper chelation therapy: increases oxidative stress in cancer cells to a level that does not allow survival because of the reduction of anti-oxidative enzymes production. It may also result in inhibition of angiogenesis and of the initiation of the angiogenic switch, because copper normally enhances endothelial cell migration and proliferation, improves binding of growth factors to endothelial cells and enhances the expression of angiogenic molecules. Copper chelation may also reduce extracellular matrix degradation and cancer spread, through reduction of MMP-9 production and probably of other collagenases and may inhibit propagation of micrometastases. However, copper chelation therapy may enhance angiogenesis through reduction of thrombospondin-1, that results into an increase in VEGF-VEGFR2 complexes and a high level of active MMP-9. These hypotheses help in understanding of the anti-angiogenic action of copper chelation therapies and of the complex network of interactions between copper and other molecules involved in angiogenesis. It may also stimulate further research regarding differences in copper metabolism, the effects of anti-copper regimens on organs, the development of resistance, and their possible angiogenic action through thrombospondin expression reduction. Copyright © 2013 Elsevier Ltd. All rights reserved.

Comparative study of copper(II)-curcumin complexes as superoxide dismutase mimics and free radical scavengers.

PubMed

Barik, Atanu; Mishra, Beena; Kunwar, Amit; Kadam, Ramakant M; Shen, Liang; Dutta, Sabari; Padhye, Subhash; Satpati, Ashis K; Zhang, Hong-Yu; Indira Priyadarsini, K

2007-04-01

Two stoichiometrically different copper(II) complexes of curcumin (stoichiometry, 1:1 and 1:2 for copper:curcumin), were examined for their superoxide dismutase (SOD) activity, free radical-scavenging ability and antioxidant potential. Both the complexes are soluble in lipids and DMSO. The formation constants of the complexes were determined by voltammetry. EPR spectra of the complexes in DMSO at 77K showed that the 1:2 Cu(II)-curcumin complex is square planar and the 1:1 Cu(II)-curcumin complex is distorted orthorhombic. Cu(II)-curcumin complex (1:1) with larger distortion from square planar structure shows higher SOD activity. These complexes inhibit gamma-radiation induced lipid peroxidation in liposomes and react with DPPH acting as free radical scavengers. One-electron oxidation of the two complexes by radiolytically generated azide radicals in Tx-100 micellar solutions produced phenoxyl radicals, indicating that the phenolic moiety of curcumin in the complexes participates in free radical reactions. Depending on the structure, these two complexes possess different SOD activities, free radical neutralizing abilities and antioxidant potentials. In addition, quantum chemical calculations with density functional theory have been performed to support the experimental observations.

Synthesis, characterization and toxicity studies of pyridinecarboxaldehydes and L-tryptophan derived Schiff bases and corresponding copper (II) complexes.

PubMed

Malakyan, Margarita; Babayan, Nelly; Grigoryan, Ruzanna; Sarkisyan, Natalya; Tonoyan, Vahan; Tadevosyan, Davit; Matosyan, Vladimir; Aroutiounian, Rouben; Arakelyan, Arsen

2016-01-01

Schiff bases and their metal-complexes are versatile compounds exhibiting a broad range of biological activities and thus actively used in the drug development process. The aim of the present study was the synthesis and characterization of new Schiff bases and their copper (II) complexes, derived from L-tryptophan and isomeric (2-; 3-; 4-) pyridinecarboxaldehydes, as well as the assessment of their toxicity in vitro . The optimal conditions of the Schiff base synthesis resulting in up to 75-85% yield of target products were identified. The structure-activity relationship analysis indicated that the location of the carboxaldehyde group at 2-, 3- or 4-position with regard to nitrogen of the pyridine ring in aldehyde component of the L-tryptophan derivative Schiff bases and corresponding copper complexes essentially change the biological activity of the compounds. The carboxaldehyde group at 2- and 4-positions leads to the higher cytotoxic activity, than that of at 3-position, and the presence of the copper in the complexes increases the cytotoxicity. Based on toxicity classification data, the compounds with non-toxic profile were identified, which can be used as new entities in the drug development process using Schiff base scaffold.

Synthesis, characterization and toxicity studies of pyridinecarboxaldehydes and L-tryptophan derived Schiff bases and corresponding copper (II) complexes

PubMed Central

Malakyan, Margarita; Babayan, Nelly; Grigoryan, Ruzanna; Sarkisyan, Natalya; Tonoyan, Vahan; Tadevosyan, Davit; Matosyan, Vladimir; Aroutiounian, Rouben; Arakelyan, Arsen

2016-01-01

Schiff bases and their metal-complexes are versatile compounds exhibiting a broad range of biological activities and thus actively used in the drug development process. The aim of the present study was the synthesis and characterization of new Schiff bases and their copper (II) complexes, derived from L-tryptophan and isomeric (2-; 3-; 4-) pyridinecarboxaldehydes, as well as the assessment of their toxicity in vitro. The optimal conditions of the Schiff base synthesis resulting in up to 75-85% yield of target products were identified. The structure-activity relationship analysis indicated that the location of the carboxaldehyde group at 2-, 3- or 4-position with regard to nitrogen of the pyridine ring in aldehyde component of the L-tryptophan derivative Schiff bases and corresponding copper complexes essentially change the biological activity of the compounds. The carboxaldehyde group at 2- and 4-positions leads to the higher cytotoxic activity, than that of at 3-position, and the presence of the copper in the complexes increases the cytotoxicity. Based on toxicity classification data, the compounds with non-toxic profile were identified, which can be used as new entities in the drug development process using Schiff base scaffold. PMID:28344771

Synthesis and spectral characterization of mono- and binuclear copper(II) complexes derived from 2-benzoylpyridine-N4-methyl-3-thiosemicarbazone: Crystal structure of a novel sulfur bridged copper(II) box-dimer

NASA Astrophysics Data System (ADS)

Jayakumar, K.; Sithambaresan, M.; Aiswarya, N.; Kurup, M. R. Prathapachandra

2015-03-01

Mononuclear and binuclear copper(II) complexes of 2-benzoylpyridine-N4-methyl thiosemicarbazone (HL) were prepared and characterized by a variety of spectroscopic techniques. Structural evidence for the novel sulfur bridged copper(II) iodo binuclear complex is obtained by single crystal X-ray diffraction analysis. The complex [Cu2L2I2], a non-centrosymmetric box dimer, crystallizes in monoclinic C2/c space group and it was found to have distorted square pyramidal geometry (Addison parameter, τ = 0.238) with the square basal plane occupied by the thiosemicarbazone moiety and iodine atom whereas the sulfur atom from the other coordinated thiosemicarbazone moiety occupies the apical position. This is the first crystallographically studied system having non-centrosymmetrical entities bridged via thiolate S atoms with Cu(II)sbnd I bond. The tridentate thiosemicarbazone coordinates in mono deprotonated thionic tautomeric form in all complexes except in sulfato complex, [Cu(HL)(SO4)]·H2O (1) where it binds to the metal centre in neutral form. The magnetic moment values and the EPR spectral studies reflect the binuclearity of some of the complexes. The spin Hamiltonian and bonding parameters are calculated based on EPR studies. In all the complexes g|| > g⊥ > 2.0023 and the g values in frozen DMF are consistent with the dx2-y2 ground state. The thermal stabilities of some of the complexes were also determined.

Pharmacological Evaluation of Naproxen Metal Complexes on Antinociceptive, Anxiolytic, CNS Depressant, and Hypoglycemic Properties

PubMed Central

Das, Narhari; Abdur Rahman, S. M.

2016-01-01

Purpose. The present study was designed to investigate the antinociceptive, anxiolytic, CNS depressant, and hypoglycemic effects of the naproxen metal complexes. Methods. The antinociceptive activity was evaluated by acetic acid-induced writhing method and radiant heat tail-flick method while anxiolytic activity was evaluated by elevated plus maze model. The CNS depressant activity of naproxen metal complexes was assessed using phenobarbitone-induced sleeping time test and the hypoglycemic test was performed using oral glucose tolerance test. Results. Metal complexes significantly (P < 0.001) reduced the number of abdominal muscle contractions induced by 0.7% acetic acid solution in a dose dependent manner. At the dose of 25 mg/kg body weight p.o. copper, cobalt, and zinc complexes exhibited higher antinociceptive activity having 59.15%, 60.56%, and 57.75% of writhing inhibition, respectively, than the parent ligand naproxen (54.93%). In tail-flick test, at both doses of 25 and 50 mg/kg, the copper, cobalt, silver, and zinc complexes showed higher antinociceptive activity after 90 minutes than the parent drug naproxen. In elevated plus maze (EPM) model the cobalt and zinc complexes of naproxen showed significant anxiolytic effects in dose dependent manner, while the copper, cobalt, and zinc complexes showed significant CNS depressant and hypoglycemic activity. Conclusion. The present study demonstrated that copper, cobalt, and zinc complexes possess higher antinociceptive, anxiolytic, CNS depressant, and hypoglycemic properties than the parent ligand. PMID:27478435

The coordination- and photochemistry of copper(i) complexes: variation of N^N ligands from imidazole to tetrazole.

PubMed

Bergmann, Larissa; Braun, Carolin; Nieger, Martin; Bräse, Stefan

2018-01-02

The prediction of coordination modes is of high importance when structure-property relationships are discussed. Herein, the coordination chemistry of copper(i) with pyridine-amines with a varying number of coordinating N-atoms, namely pyridine-benzimidazole, -triazole and -tetrazole, or their deprotonated analogues, and different phosphines was systematically studied and the photoluminescence properties of all synthesized complexes examined and related to DFT data. Each complex was characterized by single-crystal X-ray analysis and elemental analysis, and a set of prediction rules derived for the coordination chemistry of copper(i) with these ligands. A mononuclear cationic coordination motif was found for PPh 3 or DPEPhos with all N^N ligands, which exhibits blue to green luminescence of MLCT character d(Cu) → π*(pyridine-amine ligand) with quantum yields up to 46%. With the deprotonated N^N ligands, mononuclear neutral complexes were only expected with DPEPhos. The emission's nature of this complex type is strongly dependent on the electronic effects of the N^N ligand and was characterized as (ML + IL)CT transition. In contrast to the high quantum yields up to 78% for the tetrazolate complexes (as reported before), the triazolate and imidazolate based complexes show much lower emission efficiencies below 10%. Besides the mononuclear copper(i) complexes, cluster-type complexes were obtained, which show moderate luminescence in the blue to green region of the visible spectrum (469-505 nm).

Infrared spectroscopy of copper-resveratrol complexes: A joint experimental and theoretical study

NASA Astrophysics Data System (ADS)

Chiavarino, B.; Crestoni, M. E.; Fornarini, S.; Taioli, S.; Mancini, I.; Tosi, P.

2012-07-01

Infrared multiple-photon dissociation spectroscopy has been used to record vibrational spectra of charged copper-resveratrol complexes in the 3500-3700 cm-1 and 1100-1900 cm-1 regions. Minimum energy structures have been determined by density functional theory calculations using plane waves and pseudopotentials. In particular, the copper(I)-resveratrol complex presents a tetra-coordinated metal bound with two carbon atoms of the alkenyl moiety and two closest carbons of the adjoining resorcinol ring. For these geometries vibrational spectra have been calculated by using linear response theory. The good agreement between experimental and calculated IR spectra for the selected species confirms the overall reliability of the proposed geometries.

Reactivity of dinuclear copper(II) complexes towards melanoma cells: Correlation with its stability, tyrosinase mimicking and nuclease activity.

PubMed

Nunes, Cléia Justino; Borges, Beatriz Essenfelder; Nakao, Lia Sumie; Peyroux, Eugénie; Hardré, Renaud; Faure, Bruno; Réglier, Marius; Giorgi, Michel; Prieto, Marcela Bach; Oliveira, Carla Columbano; Da Costa Ferreira, Ana M

2015-08-01

In this work, the influence of two new dinuclear copper(II) complexes in the viability of melanoma cells (B16F10 and TM1MNG3) was investigated, with the aim of verifying possible correlations between their cytotoxicity and their structure. One of the complexes had a polydentate dinucleating amine-imine ligand (complex 2), and the other a tridentate imine and a diamine-bridging ligand (complex 4). The analogous mononuclear copper(II) species (complexes 1 and 3, respectively) were also prepared for comparative studies. Crystal structure determination of complex 2 indicated a square-based pyramidal geometry around each copper, coordinated to three N atoms from the ligand and the remaining sites being occupied by either solvent molecules or counter-ions. Complex 4 has a tetragonal geometry. Interactions of these complexes with human albumin protein (HSA) allowed an estimation of their relative stabilities. Complementary studies of their reactivity towards DNA indicated that all of them are able of causing significant oxidative damage, with single and double strand cleavages, in the presence of hydrogen peroxide. However, nuclease activity of the dinuclear species was very similar and much higher than that of the corresponding mononuclear compounds. Although complex 2, with a more flexible structure, exhibits a much higher tyrosinase activity than complex 4, having a more rigid environment around the metal ion, both complexes showed comparable cytotoxicity towards melanoma cells. Corresponding mononuclear complexes showed to be remarkably less reactive as tyrosinase mimics as well as cytotoxic agents. Moreover, the dinuclear complexes showed higher cytotoxicity towards more melanogenic cells. The obtained results indicated that the structure of these species is decisive for its activity towards the malignant tumor cells tested. Copyright © 2015 Elsevier Inc. All rights reserved.

Synthesis of Well-Defined Copper "N"-Heterocyclic Carbene Complexes and Their Use as Catalysts for a "Click Reaction": A Multistep Experiment that Emphasizes the Role of Catalysis in Green Chemistry

ERIC Educational Resources Information Center

Ison, Elon A.; Ison, Ana

2012-01-01

A multistep experiment for an advanced synthesis lab course that incorporates topics in organic-inorganic synthesis and catalysis and highlights green chemistry principles was developed. Students synthesized two "N"-heterocyclic carbene ligands, used them to prepare two well-defined copper(I) complexes and subsequently utilized the complexes as…

Photoinduced water oxidation sensitized by a tetranuclear Ru(II) dendrimer.

PubMed

La Ganga, Giuseppina; Nastasi, Francesco; Campagna, Sebastiano; Puntoriero, Fausto

2009-12-07

A multimetallic ruthenium(II) dendrimer is used for the first time to photosensitize dioxygen production from water by IrO2 nanoparticles; the system is more efficient than an analogous system based on the more commonly used [Ru(bpy)3]2+-type photosensitizers, in particular for the ability of the dendrimer to take advantage of the red portion of the solar spectrum.

The copper complexation ability of a synthetic humic-like acid formed by an abiotic humification process and the effect of experimental factors on its copper complexation ability.

PubMed

Yang, Ting; Hodson, Mark E

2018-03-26

Humic acids have an important impact on the distribution, toxicity, and bioavailability of hazardous metals in the environment. In this study, a synthetic humic-like acid (SHLA) was prepared by an abiotic humification process using catechol and glycine as humic precursors and a MnO 2 catalyst. The effect of physico-chemical conditions (ionic strength from 0.01 to 0.5 M NaNO 3 , pH from 4 to 8, temperature from 25 to 45 °C, and humic acid concentration from 5 to 100 mg/L) on the complexation ability of SHLA for Cu 2+ were investigated. A commercial humic acid (CHA, CAS: 1415-93-6) from Sigma-Aldrich was also studied for comparison. The results showed that for pH 4 to 8, the conditional stability constants (log K) of SHLA and CHA were in the range 5.63-8.62 and 4.87-6.23, respectively, and complexation capacities (CC) were 1.34-2.61 and 1.42-2.31 mmol/g, respectively. The Cu complexation ability of SHLA was higher than that of the CHA due to its higher number of acidic functional groups (SHLA 19.19 mmol/g; CHA 3.87 mmol/g), extent of humification and aromaticity (AL/AR: 0.333 (SHLA); 1.554 (CHA)), and O-alkyl functional groups (SHLA 15.56%; CHA 3.45%). The log K and complexation efficiency (fraction of metal bound to SHLA) of SHLA were higher at higher pH, lower ionic strength, higher temperature, and higher SHLA concentration. Overall, SHLA was a good and promising complexation agent for copper in both soil washing of copper contaminated soil and the treatment of copper-containing wastewater.

Carbonate formation within a nickel dimer: synthesis of a coordinatively unsaturated bis(mu-hydroxo) dinickel complex and its reactivity toward carbon dioxide.

PubMed

Wikstrom, Jeffrey P; Filatov, Alexander S; Mikhalyova, Elena A; Shatruk, Michael; Foxman, Bruce M; Rybak-Akimova, Elena V

2010-03-14

The tridentate aminopyridine ligand bearing a bulky tert-butyl substituent at the amine nitrogen, tert-butyl-dipicolylamine (tBuDPA), occupies three coordination sites in six-coordinate complexes of nickel(ii), leaving the remaining three sites available for additional ligand binding and activation. New crystallographically characterized complexes include two mononuclear species with 1:1 metal:ligand complexation: a trihydrate solvate (1.3H(2)O) and a monohydrate biacetonitrile solvate (1.H(2)O.2CH(3)CN). Complexation in the presence of sodium hydroxide results in a bis(mu-hydroxo) complex (2), the bridging hydroxide anions of which are labile and become displaced by methoxide anions in methanol solvent, affording bis-methoxo-bridged (4). Nickel(II) centers in 2 are five-coordinate and antiferromagnetically coupled (with J = -31.4(5) cm(-1), H = -2JS(1)S(2), in agreement with Ni-O-Ni angle of 103.7 degrees). Bridging hydroxide or alkoxide anions in coordinatively unsaturated dinuclear nickel(II) complexes with tBuDPA react as active nucleophiles. 2 readily performs carbon dioxide fixation, resulting in the formation of a bis(mu-carbonato) tetrameric complex (3), which features a novel binding geometry in the form of an inverted butterfly-type nickel-carbonate core. Temperature-dependent magnetic measurements of tetranuclear carbonato-bridged revealed relatively weak antiferromagnetic coupling (J(1) = -3.1(2) cm(-1)) between the two nickel centers in the core of the cluster, as well as weak antiferromagnetic pairwise interactions (J(2) = J(3) = -4.54(5) cm(-1)) between central and terminal nickel ions.

40 CFR 721.2577 - Copper complex of (substituted sulfonaphthyl azo substituted phenyl) disulfonaphthyl azo, amine...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Copper complex of (substituted sulfonaphthyl azo substituted phenyl) disulfonaphthyl azo, amine salt (generic). 721.2577 Section 721.2577 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES...

Towards a thermally regenerative all-copper redox flow battery.

PubMed

Peljo, Pekka; Lloyd, David; Doan, Nguyet; Majaneva, Marko; Kontturi, Kyösti

2014-02-21

An all-copper redox flow battery based on strong complexation of Cu(+) with acetonitrile is demonstrated, exhibiting reasonable battery performance. More interestingly, the battery can be charged by heat sources of 100 °C, by distilling off the acetonitrile. This destabilizes the Cu(+) complex, leading to recovery of the starting materials.

Synthesis, crystal structure and DFT studies of a novel dinuclear copper(I) complex with triphenylphosphine and 2-mercaptonicotinic acid

NASA Astrophysics Data System (ADS)

Ahmad, Tayyaba; Mahmood, Rashid; Georgieva, Ivelina; Zahariev, Tsvetan; Tahir, Muhammad Nawaz; Shaheen, Muhammad Ashraf; Gilani, Mazhar Amjad; Ahmad, Saeed

2018-02-01

A novel dinuclear copper(I) complex, {[Cu2(Mnt)2(PPh3)2Cl2].2H2O.CH3CN}2 (1) (Mnt = Mercaptonicotinic acid, PPh3 = triphenylphosphine) was prepared and its structure was determined by X-ray crystallography. The complex 1 consists of two dinuclear molecules and in each molecule, the two copper atoms are bridged by S atoms of N-protonated mercaptonicotinic acid forming a four-membered ring. The planar Cu2S2 core is characterized by significant cuprophilic interactions (Cusbnd Cu distance = 2.7671(8), 2.8471(8) Å). Each copper atom in 1 is coordinated by two sulfur atoms of Mnt, one phosphorus atom of PPh3 and a chloride ion adopting a tetrahedral geometry. The calculated Gibbs energies for reaction in CH3CN supported the experimental structure and predicted more favorable formation of dinuclear Cu(I) complex as compared to the mononuclear Cu(I) complex. The dinuclear complex is stabilized by 65.98 kJ mol-1 by coupling of two mononuclear Cu(I) complexes. The IR spectra of 1 and Mnt ligand were reliably interpreted and the Mnt vibrations, which are sensitive to the ligand coordination to Cu(I) ion in 1 were selected with the help of DFT/ωB97XD calculations.

Synthesis and Characterization of Tetrakis(2-amino-3-methylpyridine)copper(II) Sulfate Tetrahydrate

NASA Astrophysics Data System (ADS)

Rahardjo, S. B.; Saraswati, T. E.; Masykur, A.; Finantrena, N. N. F.; Syaima, H.

2018-04-01

The complex of Tetrakis(2-amino-3-methylpyridine)copper(II) sulfate tetrahydrate has been synthesized in a ratio of 1: 6 metal to ligand in methanol. The percentage of copper in the complex measured by Atomic Absorption Spectrometer (AAS) showed the complex formula was Cu(2-amino-3-metilpyridine)4SO4(H2O)n (n = 3, 4, or 5). The analysis of TG/DTA showed that 1 mole of complex contains 4 moles of H2O. The conductivity measurement indicated that the complex is in 1 to 1 electrolyte. The formula of the complex was estimated as [Cu(2-amino-3-metilpyridine)4]SO4·4H2O. The complex was paramagnetic with µeff of 1.85 BM. The UV-Vis spectra showed a band peak at 730 nm with an electronic transition Eg→T2g. IR spectral data indicated that the functional groups of N-pyridine 2-amino-3-metilpyridine coordinated to ion Cu(II). The geometry of the complex was probably square planar.

Cyclam Derivatives with a Bis(phosphinate) or a Phosphinato-Phosphonate Pendant Arm: Ligands for Fast and Efficient Copper(II) Complexation for Nuclear Medical Applications.

PubMed

David, Tomáš; Kubíček, Vojtěch; Gutten, Ondrej; Lubal, Přemysl; Kotek, Jan; Pietzsch, Hans-Jürgen; Rulíšek, Lubomír; Hermann, Petr

2015-12-21

Cyclam derivatives bearing one geminal bis(phosphinic acid), -CH2PO2HCH2PO2H2 (H2L(1)), or phosphinic-phosphonic acid, -CH2PO2HCH2PO3H2 (H3L(2)), pendant arm were synthesized and studied as potential copper(II) chelators for nuclear medical applications. The ligands showed good selectivity for copper(II) over zinc(II) and nickel(II) ions (log KCuL = 25.8 and 27.7 for H2L(1) and H3L(2), respectively). Kinetic study revealed an unusual three-step complex formation mechanism. The initial equilibrium step leads to out-of-cage complexes with Cu(2+) bound by the phosphorus-containing pendant arm. These species quickly rearrange to an in-cage complex with cyclam conformation II, which isomerizes to another in-cage complex with cyclam conformation I. The first in-cage complex is quantitatively formed in seconds (pH ≈5, 25 °C, Cu:L = 1:1, cM ≈ 1 mM). At pH >12, I isomers undergo nitrogen atom inversion, leading to III isomers; the structure of the III-[Cu(HL(2))] complex in the solid state was confirmed by X-ray diffraction analysis. In an alkaline solution, interconversion of the I and III isomers is mutual, leading to the same equilibrium isomeric mixture; such behavior has been observed here for the first time for copper(II) complexes of cyclam derivatives. Quantum-chemical calculations showed small energetic differences between the isomeric complexes of H3L(2) compared with analogous data for isomeric complexes of cyclam derivatives with one or two methylphosphonic acid pendant arm(s). Acid-assisted dissociation proved the kinetic inertness of the complexes. Preliminary radiolabeling of H2L(1) and H3L(2) with (64)Cu was fast and efficient, even at room temperature, giving specific activities of around 70 GBq of (64)Cu per 1 μmol of the ligand (pH 6.2, 10 min, ca. 90 equiv of the ligand). These specific activities were much higher than those of H3nota and H4dota complexes prepared under identical conditions. The rare combination of simple ligand synthesis, very fast copper(II) complex formation, high thermodynamic stability, kinetic inertness, efficient radiolabeling, and expected low bone tissue affinity makes such ligands suitably predisposed to serve as chelators of copper radioisotopes in nuclear medicine.

Newly identified interfibrillar collagen crosslinking suppresses cell proliferation and remodelling.

PubMed

Marelli, Benedetto; Le Nihouannen, Damien; Hacking, S Adam; Tran, Simon; Li, Jingjing; Murshed, Monzur; Doillon, Charles J; Ghezzi, Chiara E; Zhang, Yu Ling; Nazhat, Showan N; Barralet, Jake E

2015-06-01

Copper is becoming recognised as a key cation in a variety of biological processes. Copper chelation has been studied as a potential anti-angiogenic strategy for arresting tumour growth. Conversely the delivery of copper ions and complexes in vivo can elicit a pro-angiogenic effect. Previously we unexpectedly found that copper-stimulated intraperitoneal angiogenesis was accompanied by collagen deposition. Here, in hard tissue, not only was healing accelerated by copper, but again enhanced deposition of collagen was detected at 2 weeks. Experiments with reconstituted collagen showed that addition of copper ions post-fibrillogenesis rendered plastically-compressed gels resistant to collagenases, enhanced their mechanical properties and increased the denaturation temperature of the protein. Unexpectedly, this apparently interfibrillar crosslinking was not affected by addition of glucose or ascorbic acid, which are required for crosslinking by advanced glycation end products (AGEs). Fibroblasts cultured on copper-crosslinked gels did not proliferate, whereas those cultured with an equivalent quantity of copper on either tissue culture plastic or collagen showed no effect compared with controls. Although non-proliferative, fibroblasts grown on copper-cross-linked collagen could migrate, remained metabolically active for at least 14 days and displayed a 6-fold increase in Mmps 1 and 3 mRNA expression compared with copper-free controls. The ability of copper ions to crosslink collagen fibrils during densification and independently of AGEs or Fenton type reactions is previously unreported. The effect on MMP susceptibility of collagen and the dramatic change in cell behaviour on this crosslinked ECM may contribute to shedding some light on unexplained phenomena as the apparent benefit of copper complexation in fibrotic disorders or the enhanced collagen deposition in response to localised copper delivery. Copyright © 2015 Elsevier Ltd. All rights reserved.

Design, syntheses, characterization, and cytotoxicity studies of novel heterobinuclear oxindolimine copper(II)-platinum(II) complexes.

PubMed

Aranda, Esther Escribano; Matias, Tiago Araújo; Araki, Koiti; Vieira, Adriana Pires; de Mattos, Elaine Andrade; Colepicolo, Pio; Luz, Carolina Portela; Marques, Fábio Luiz Navarro; da Costa Ferreira, Ana Maria

2016-12-01

Herein, the design and syntheses of two new mononuclear oxindolimine-copper(II) (1 and 2) and corresponding heterobinuclear oxindolimine Cu(II)Pt(II) complexes (3 and 4), are described. All the isolated complexes were characterized by spectroscopic techniques (UV/Vis, IR, EPR), in addition to elemental analysis and mass spectrometry. Cyclic voltammetry (CV) measurements showed that in all cases, one-electron quasi-reversible waves were observed, and ascribed to the formation of corresponding copper(I) complexes. Additionally, waves related to oxindolimine ligand reduction was verified, and confirmed using analogous oxindolimine-Zn(II) complexes. The Pt(IV/II) reduction, and corresponding oxidation, for complexes 3 and 4 occurred at very close values to those observed for cisplatin. By complementary fluorescence studies, it was shown that glutathione (GSH) cannot reduce any of these complexes, under the experimental conditions (room temperature, phosphate buffer 50mM, pH7.4), using an excess of 20-fold [GSH]. All these complexes showed characteristic EPR spectral profile, with parameters values g ǁ >g ⊥ suggesting an axially distorted environment around the copper(II) center. Interactions with calf thymus-DNA, monitored by circular dichroism (CD), indicated different effects modulated by the ligands. Finally, the cytotoxicity of each complex was tested toward different tumor cells, in comparison to cisplatin, and low values of IC 50 in the range 0.6 to 4.0μM were obtained, after 24 or 48h incubation at 37°C. The obtained results indicate that such complexes can be promising alternative antitumor agents. Copyright © 2016 Elsevier Inc. All rights reserved.

Synthesis of Bis(1,2-Dimethylimidazole)Copper(I)Hexafluorophosphate: An Experiment Using a Glove Box

ERIC Educational Resources Information Center

Niewahner, J. H.; Walters, Keith A.

2007-01-01

A detailed description of the synthesis of bis(1,2-dimethylimidazole)copper(I) hexafluorophosphate by using techniques in a glove box is presented. The results shows that the synthesis of the copper complex has a distinct color change indicating by-product oxidation by oxygen.

Theoretical, biological and in silico studies of pendant-armed heteroleptic copper(II) phenolate complexes

NASA Astrophysics Data System (ADS)

Arthi, P.; Mahendiran, D.; Shobana, S.; Srinivasan, P.; Rahiman, A. Kalilur

2018-06-01

A new series of pendant-armed heteroleptic copper(II) phenolate complexes of the type [CuL1-3(diimine)] (1-6) have been synthesized by the reaction of pendant-armed ligands 2,2'-(benzoyliminodiethylene)bissalicylidene (H2L1), 2,2'-(4-nitrobenzoyliminodiethylene)bissalicylidene (H2L2) or 2,2'-(3,5-dinitrobenzoyliminodiethylene)bissalicylidene (H2L3) with coligands (diimine; 2,2‧-bipyridyl (bpy) or 1,10-phenanthroline (phen)) in the presence of copper(II) chloride, and characterized by spectroscopic techniques. The seven coordinated pentagonal-bipyramidal geometry around the copper(II) center was inferred from the electronic spectra of the complexes. The bond length, bond angle and HOMO-LUMO energy gap calculations were carried out by DFT studies, using Gaussian 03 program. Electrochemical studies of the mononuclear complexes evidenced one-electron irreversible reduction wave in the cathodic region (Epc = -0.61 to -0.65 V). Experimental and in silico molecular docking studies support groove mode of binding with DNA. Further, the molecular docking studies of complexes with B-DNA indicate the binding of the guanine-cytosine residues in the minor groove of the DNA. Molecular docking studies also revealed the interaction of complexes with protein ERK2 kinase and significant topoisomerase (Topo-I) inhibitory activity. All the complexes display pronounced cleavage activity against supercoiled pBR322 DNA in the presence of H2O2. In vitro cytotoxicity of the complexes was tested against liver cancer cell line (HepG2) by MTT reduction assay.

Biomineralization of copper: Solutions for waste remediation and biomining

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashby, C.R.; Thompson, S.A.; Crusberg, T.C.

1997-12-31

The fungus Penicillium ochro-chloron is able to extract copper from aqueous solutions and form insoluble copper precipitates within the matrix of fungal mycelia. The formation of these complexes is probably a detoxification mechanism used by the organism to deal with the potentially lethal concentrations of heavy metals. Metal immobilization occurs external to the cells but within the mycelia when the solubility products of copper phosphate and copper oxalate are exceeded. This process may be exploited in biomining to remove and recover copper and perhaps other heavy metals that have become solubilized in pit mine lakes.

Synthesis of mononuclear copper(II) complexes of N3O2 and N4O2 donors containing Schiff base ligands: Theoretical and biological observations

NASA Astrophysics Data System (ADS)

Mancha Madha, K.; Gurumoorthy, P.; Arul Antony, S.; Ramalakshmi, N.

2017-09-01

A new series of six mononuclear copper(II) complexes were synthesized from N3O2 and N4O2 donors containing Schiff base ligands, and characterized by various spectral methods. The geometry of the complexes was determined using UV-Vis, EPR and DFT calculations. The complexes of N3O2 donors (1-3) adopted square pyramidal geometry and the remaining complexes of N4O2 donors (4-6) show distorted octahedral geometry around copper(II) nuclei. Redox properties of the complexes show a one-electron irreversible reduction process in the cathodic potential (Epc) region from -0.74 to -0.98 V. The complexes show potent antioxidant activity against DPPH radicals. Molecular docking studies of complexes showed σ-π interaction, hydrogen bonding, electrostatic and van der Waals interactions with VEGFR2 kinase receptor. In vitro cytotoxicity of the complexes was tested against human breast cancer (MDA-MB-231) cell lines and one normal human dermal fibroblasts (NHDF) cell line through MTT assay. The morphological assessment data obtained by Hoechst 33258 and AO/EB staining revealed that the complexes induce apoptosis pathway of cell death.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rana, Abhinandan; Jana, Swapan Kumar; Datta, Sayanti

The synthesis of two new lead(II) coordination polymers, [Pb{sub 2}(mpic){sub 4}(H{sub 2}O)]·0.5H{sub 2}O (1) and [Pb{sub 2}(phen){sub 2}(cit)(mes)]·2H{sub 2}O (2) has been reported, where mpic=3-methyl picolinate, phen=o-phenanthroline, H{sub 2}cit=citraconic acid, H{sub 2}mes mesaconic acid. X-ray single crystal diffraction analyses showed that the complexes comprise topologically different 1D polymeric chains stabilized by weak interactions and both containing tetranuclear Pb{sub 4} units connected by carboxylate groups. In compound 1 3-methylpicolinic acid is formed in situ from 3-methyl piconitrile, and mesaconate and citraconate anions were surprisingly formed from itaconic acid during the synthesis of 2. The photoluminescence and thermal properties of the complexesmore » have been studied. - Graphical abstract: Two new topologically different 1D coordination polymers formed by Pb{sub 4} clusters have been synthesized and characterized by X-ray analysis. The luminescence and thermal properties have been studied. Display Omitted - Highlights: • Both the complexes, made up of different ligands, forms topologycally different 1D polymeric chains containing Pb{sub 4} clusters. • The final structures are stabilized by weak interactions (H-bond, π∙∙∙π stacking). • In complex 1, the 3-methylpicolinic acid is generated in situ from 3-methyl piconitrile. • Mesaconate and citraconate anions are surprisingly formed in situ from itaconic acid during the synthesis of complex 2, indicating an exceptional transformation.« less

Polymeric networks of copper(II) phenylmalonate with heteroaromatic n-donor ligands: synthesis, crystal structure, and magnetic properties.

PubMed

Pasán, Jorge; Sanchiz, Joaquín; Ruiz-Pérez, Catalina; Lloret, Francesc; Julve, Miguel

2005-10-31

Two new phenylmalonate-bridged copper(II) complexes with the formulas [Cu(4,4'-bpy)(Phmal)](n).2nH(2)O (1) and [Cu(2,4'-bpy)(Phmal)(H(2)O)](n)() (2) (Phmal = phenylmalonate dianion, 4,4'-bpy = 4,4'-bipyridine, 2,4'-bpy = 2,4'-bipyridine) have been synthesized and characterized by X-ray diffraction. Complex 1 crystallizes in monoclinic space group P2(1), Z = 4, with unit cell parameters of a = 9.0837(6) Angstroms, b = 9.3514(4) Angstroms, c = 11.0831(8) Angstroms, and beta = 107.807(6) degrees , whereas complex 2 crystallizes in orthorhombic space group C2cb, Z = 8, with unit cell parameters of a = 10.1579(7) Angstroms, b = 10.3640(8) Angstroms, and c = 33.313(4) Angstroms. The structures of 1 and 2 consist of layers of copper(II) ions with bridging bis-monodentate phenylmalonate (1 and 2) and 4,4'-bpy (1) ligands and terminal monodentate 2,4'-bpy (2) groups. Each layer in 1 contains rectangles with dimensions of 11.08 x 4.99 Angstroms(2), the edges being defined by the Phmal and 4,4'-bpy ligands. The intralayer copper-copper separations in 1 through the anti-syn equatorial-apical carboxylate-bridge and the 4,4'-bpy molecule are 4.9922(4) and 11.083(1) Angstroms, respectively. The anti-syn equatorial-equatorial carboxylate bridge links the copper(II) atoms in complex 2 within each layer with a mean copper-copper separation of 5.3709(8) Angstroms. The presence of 2,4'-bpy as a terminal ligand accounts for the large interlayer separation of 15.22 Angstroms. The copper(II) environment presents a static pseudo-Jahn-Teller disorder which has been studied by EPR and low-temperature X-ray diffraction. Magnetic susceptibility measurements of both compounds in the temperature range 2-290 K show the occurrence of weak antiferromagnetic [J = -0.59(1) cm(-1) (1)] and ferromagnetic [J = +0.77(1) cm(-1) (2)] interactions between the copper(II) ions. The conformation of the phenylmalonate-carboxylate bridge and other structural factors, such as the planarity of the exchange pathway in 1, account for the different nature of the magnetic interaction.

Structure of the manganese complex in photosystem II: insights from X-ray spectroscopy.

PubMed Central

Yachandra, Vittal K

2002-01-01

We have used Mn K-edge absorption and Kbeta emission spectroscopy to determine the oxidation states of the Mn complex in the various S states. We have started exploring the new technique of resonant inelastic X-ray scattering spectroscopy; this technique can be characterized as a Raman process that uses K-edge energies (1s to 4p, ca. 6550 eV) to obtain L-edge-like spectra (2p to 3d, ca. 650 eV). The relevance of these data to the oxidation states and structure of the Mn complex is presented. We have obtained extended X-ray absorption fine structure data from the S(0) and S(3) states and observed heterogeneity in the Mn-Mn distances leading us to conclude that there may be three rather than two di-mu-oxo-bridged units present per tetranuclear Mn cluster. In addition, we have obtained data using Ca and Sr X-ray spectroscopy that provide evidence for a heteronuclear Mn-Ca cluster. The possibility of three di-mu-oxo-bridged Mn-Mn moieties and the proximity of Ca is incorporated into developing structural models for the Mn cluster. The involvement of bridging and terminal O ligands of Mn in the mechanism of oxygen evolution is discussed in the context of our X-ray spectroscopy results. PMID:12437873

Bonding and structure of copper nitrenes.

PubMed

Cundari, Thomas R; Dinescu, Adriana; Kazi, Abul B

2008-11-03

Copper nitrenes are of interest as intermediates in the catalytic aziridination of olefins and the amination of C-H bonds. However, despite advances in the isolation and study of late-transition-metal multiply bonded complexes, a bona fide structurally characterized example of a terminal copper nitrene has, to our knowledge, not been reported. In anticipation of such a report, terminal copper nitrenes are studied from a computational perspective. The nitrene complexes studied here are of the form (beta-diketiminate)Cu(NPh). Density functional theory (DFT), complete active space self-consistent-field (CASSCF) electronic structure techniques, and hybrid quantum mechanical/molecular mechanical (QM/MM) methods are employed to study such species. While DFT methods indicate that a triplet (S = 1) is the ground state, CASSCF calculations indicate that a singlet (S = 0) is the ground state, with only a small energy gap between the singlet and triplet. Moreover, the ground-state (open-shell) singlet copper nitrene is found to be highly multiconfigurational (i.e., biradical) and to possess a bent geometry about the nitrene nitrogen, contrasting with the linear nitrene geometry of the triplet copper nitrenes. CASSCF calculations also reveal the existence of a closed-shell singlet state with some degree of multiple bonding character for the copper-nitrene bond.

Disulfiram and Copper Ions Kill Mycobacterium tuberculosis in a Synergistic Manner

PubMed Central

Dalecki, Alex G.; Haeili, Mehri; Shah, Santosh; Speer, Alexander; Niederweis, Michael; Kutsch, Olaf

2015-01-01

Tuberculosis is a severe disease affecting millions worldwide. Unfortunately, treatment strategies are hampered both by the prohibitively long treatment regimen and the rise of drug-resistant strains. Significant effort has been expended in the search for new treatments, but few options have successfully emerged, and new treatment modalities are desperately needed. Recently, there has been growing interest in the synergistic antibacterial effects of copper ions (CuII/I) in combination with certain small molecular compounds, and we have previously reported development of a drug screening strategy to harness the intrinsic bactericidal properties of CuII/I. Here, we describe the copper-dependent antimycobacterial properties of disulfiram, an FDA-approved and well-tolerated sobriety aid. Disulfiram was inhibitory to mycobacteria only in the presence of CuII/I and exerted its bactericidal activity well below the active concentration of CuII/I or disulfiram alone. No other physiologically relevant bivalent transition metals (e.g., FeII, NiII, MnII, and CoII) exhibited this effect. We demonstrate that the movement of the disulfiram-copper complex across the cell envelope is porin independent and can inhibit intracellular protein functions. Additionally, the complex is able to synergistically induce intracellular copper stress responses significantly more than CuII/I alone. Our data suggest that by complexing with disulfiram, CuII/I is likely allowed unfettered access to vulnerable intracellular components, bypassing the normally sufficient copper homeostatic machinery. Overall, the synergistic antibacterial activity of CuII/I and disulfiram reveals the susceptibility of the copper homeostasis system of Mycobacterium tuberculosis to chemical attacks and establishes compounds that act in concert with copper as a new class of bacterial inhibitors. PMID:26033731

Acetate-Bridged Platinum(III) Complexes Derived from Cisplatin

PubMed Central

Wilson, Justin J.

2012-01-01

Oxidation of the acetate-bridged half-lantern platinum(II) complex, cis-[PtII(NH3)2(µ-OAc)2PtII(NH3)2](NO3)2, [1](NO3)2, with iodobenzene dichloride or bromine generates the halide-capped platinum(III) species, cis-[XPtIII(NH3)2(µ-OAc)2PtIII(NH3)2X](NO3)2, where X is Cl in [2](NO3)2, or Br in [3](NO3)2, respectively. These three complexes, characterized structurally by X-ray crystallography, feature short (≈ 2.6 Å) Pt–Pt separations, consistent with formation of a formal metal-metal bond upon oxidation. Elongated axial Pt–X distances occur, reflecting the strong trans influence of the metal-metal bond. The three structures are compared to those of other known dinuclear platinum complexes. A combination of 1H, 13C, 14N, and 195Pt NMR spectroscopy was used to characterize [1]2+–[3]2+ in solution. All resonances shift downfield upon oxidation of [1]2+ to [2]2+ and [3]2+. For the platinum(III) complexes, the 14N and 195Pt resonances exhibit decreased linewidths by comparison to those of [1]2+. Density functional theory (DFT) calculations suggest that the decrease in 14N linewidth arises from a diminished electric field gradient (EFG) at the 14N nuclei in the higher valent compounds. The oxidation of [1](NO3)2 with the alternative oxidizing agent, bis(trifluoroacetoxy) iodobenzene, affords the novel tetranuclear complex, cis-[(O2CCF3)PtIII(NH3)2(µ-OAc)2PtIII(NH3)(µ-NH2)]2(NO3)4, [4](NO3)4, also characterized structurally by X-ray crystallography. In solution, this complex exists as a mixture of species, the identities of which are proposed. PMID:22946515

X-Ray absorption spectroscopy quantitative analysis of biomimetic copper(II) complexes with tridentate nitrogen ligands mimicking the tris(imidazole) array of protein centres.

PubMed

Borghi, Elena; Casella, Luigi

2010-02-21

In this study copper(ii) complexes with the tridentate nitrogen ligand bis[2-(1-methylbenzimidazol-2-yl)ethyl]amine (2-BB) are considered as model compounds for the Cu-tris(imidazole) array found in several copper proteins. 2-BB chelates copper(ii) forming two six-membered rings and the complexes contain methanol, nitrite, azide and water as ancillary ligands; both the coordination numbers and stereochemistries differ in these complexes. Their key structural features were investigated by using full multiple-scattering theoretical analysis of the copper K-edge X-ray absorption spectrum with the MXAN code. We showed that using cluster sizes large enough to include all atoms of the ligand, the analysis of the XANES region can give both a structural model of the metal centre and map the structure of the 2-BB complexes. Complex [Cu(2-BB)(N(3))](+) provided a critical test through the comparison of the XANES simulation results with crystallographic data, thus permitting the extension of the method to the complex [Cu(2-BB)(H(2)O)(n)](+) (n = 1 or 2), for which crystallographic data are not available but is expected to bear a five-coordinated Cu(3N)(2O) core (n = 2). The structural data of [Cu(2-BB)(MeOH)(ClO(4))](+) and [Cu(2-BB)(NO(2))](+), both with a Cu(3N)(2O) core but with a different stereochemistry, were used as the starting parameters for two independent simulations of the XANES region of the [Cu(2-BB)(H(2)O)(2)](+) cation. The two structural models generated by simulation converge towards a structure for the aqua-cation with a lower coordination number. New calculations, where four-coordinated Cu(3N)(O) cores were considered as the starting structures, validated that the structure of the aqua-complex in the powder state has a copper(ii) centre with a four-coordinated Cu(3N)(O) core and a molecular formula [Cu(2-BB)(H(2)O)](ClO(4)).(H(2)O). A water solvation molecule, presumed to be disordered from the simulations with the two Cu(3N)(2O) cores, is present. The successful treatment of this Cu-2-BB complex system allows the extension of the method to other biomimetic compounds when a structural characterization is lacking.

Halo-substituted thiosemicarbazones and their copper(II), nickel(II) complexes: Detailed spectroscopic characterization and study of antitumour activity against HepG2 human hepatoblastoma cells

NASA Astrophysics Data System (ADS)

Jagadeesh, M.; Kalangi, Suresh K.; Sivarama Krishna, L.; Reddy, A. Varada

2014-01-01

Copper(II) and nickel(II) complexes of two different halogen substituted thiosemicarbazone ligands were synthesized. The ligands 3,4-difluoroacetophenone thiosemicarbazone (1) and 2-bromo-4'-chloroacetophenone thiosemicarbazone (2) were characterized and confirmed spectroscopically by FT-IR, FT-Raman, UV-vis and fluorescence spectral analysis, while the respective copper(II) complexes [Cu(C9H9N3F2S)2Cl2] (1a), [Cu(C9H9N3ClBrS)2Cl2] (2a) and nickel(II) complexes [Ni(C9H9N3F2S)2] (1b), [Ni(C9H9N3ClBrS)2] (2b) were characterized by FT-IR, UV-vis and electron paramagnetic spectroscopy (EPR). The EPR spectra of the Cu(II) complexes provided the rhombic octahedral and axial symmetry of the complexes 1a and 2a respectively. For the complex 1a, the g values calculated as g1 = 2.1228, g2 = 2.0706 and g3 = 2.001 between 2900 and 3300 G. While for the complex 2a, a set of two resonance absorptions were observed. The synthesized compounds were tested for antitumor activity and showed that the ability to kill liver cancer cells significantly. Out of all the synthesized compounds, copper(II) complexes 1a and 2a showed high cytotoxic effect on liver cancer cells with 67.51% and 42.77% of cytotoxicity respectively at 100 μM.

Synthesis and spectral characterization of mono- and binuclear copper(II) complexes derived from 2-benzoylpyridine-N⁴-methyl-3-thiosemicarbazone: crystal structure of a novel sulfur bridged copper(II) box-dimer.

PubMed

Jayakumar, K; Sithambaresan, M; Aiswarya, N; Kurup, M R Prathapachandra

2015-03-15

Mononuclear and binuclear copper(II) complexes of 2-benzoylpyridine-N(4)-methyl thiosemicarbazone (HL) were prepared and characterized by a variety of spectroscopic techniques. Structural evidence for the novel sulfur bridged copper(II) iodo binuclear complex is obtained by single crystal X-ray diffraction analysis. The complex [Cu2L2I2], a non-centrosymmetric box dimer, crystallizes in monoclinic C2/c space group and it was found to have distorted square pyramidal geometry (Addison parameter, τ=0.238) with the square basal plane occupied by the thiosemicarbazone moiety and iodine atom whereas the sulfur atom from the other coordinated thiosemicarbazone moiety occupies the apical position. This is the first crystallographically studied system having non-centrosymmetrical entities bridged via thiolate S atoms with Cu(II)I bond. The tridentate thiosemicarbazone coordinates in mono deprotonated thionic tautomeric form in all complexes except in sulfato complex, [Cu(HL)(SO4)]·H2O (1) where it binds to the metal centre in neutral form. The magnetic moment values and the EPR spectral studies reflect the binuclearity of some of the complexes. The spin Hamiltonian and bonding parameters are calculated based on EPR studies. In all the complexes g||>g⊥>2.0023 and the g values in frozen DMF are consistent with the d(x2-y2) ground state. The thermal stabilities of some of the complexes were also determined. Copyright © 2014 Elsevier B.V. All rights reserved.

Copper-promoted methylene C-H oxidation to a ketone derivative by O2.

PubMed

Deville, Claire; McKee, Vickie; McKenzie, Christine J

2017-01-17

The methylene group of the ligand 1,2-di(pyridin-2-yl)-ethanone oxime (dpeo) is slowly oxygenated by the O 2 in air under ambient conditions when [Cu(dpeo) 2 ](ClO 4 ) 2 is dissolved in ethanol or acetonitrile. An initial transient ketone product, 2-(hydroxyimino)-1,2-di(pyridine-2-yl)ethanone, (hidpe) was characterized in the heteroleptic copper(ii) complex [Cu(bpca)(hidpe)](ClO 4 ). The co-ligand in this complex, N-(2'-pyridylcarbonyl)pyridine-2-carboximidate (bpca - ), is derived from a copper-promoted Beckmann rearrangement of hidpe. In the presence of bromide only [Cu(bpca)Br] is isolated. When significant water is present in reaction mixtures copper complexes of dpeo, hidpe and bpca - are not recovered and [Cu(pic) 2 H 2 O] is isolated. This occurs since two equivalents of picolinate are ultimately generated from one equivalent of oxidized and hydrolysed dpeo. The copper-dependent O 2 activation and consequent stoichiometric dpeo C-H oxidation is reminiscent of the previously observed catalysis of dpeo oxidation by Mn(ii) [C. Deville, S. K. Padamati, J. Sundberg, V. McKee, W. R. Browne, C. J. McKenzie, Angew. Chem., Int. Ed., 2016, 55, 545-549]. By contrast dpeo oxidation is not observed during complexation reactions with other late transition metal(ii) ions (M = Fe, Co, Ni, Zn) under aerobic conditions. In these cases bis and tris complexes of bidentate dpeo are isolated in good yields. It is interesting to note that dpeo is not oxidised by H 2 O 2 in the absence of Cu or Mn, suggesting that metal-based oxidants capable of C-H activation are produced from the dpeo-Cu/Mn systems and specifically O 2 . The metastable copper complexes [Cu(dpeo) 2 ](ClO 4 ) 2 and [Cu(bpca)(hidpe)](ClO 4 ), along with [NiX 2 (dpeo) 2 ] (X = Cl, Br), [Ni(dpeo) 3 ](ClO 4 ) 2 , [Co(dpeo) 3 ](ClO 4 ) 3 and the mixed valence complex [Fe III Fe(dpeo-H) 3 (dpeo) 3 ](PF 6 ) 4 , have been structurally characterized.

Protective role of quercetin against copper(II)-induced oxidative stress: A spectroscopic, theoretical and DNA damage study.

PubMed

Jomova, Klaudia; Lawson, Michael; Drostinova, Lenka; Lauro, Peter; Poprac, Patrik; Brezova, Vlasta; Michalik, Martin; Lukes, Vladimir; Valko, Marian

2017-12-01

The radical scavenging and metal chelating properties of flavonoids indicate that they may play a protective role in diseases with perturbed metal homeostasis such as Alzheimer's disease. In this work we investigated the effect of the coordination of quercetin to copper(II) in view of the formation of ROS in Cu-catalyzed Fenton reaction. ABTS and DPPH assays confirmed that the copper(II)-quercetin complex exhibits a stronger radical scavenging activity than does quercetin alone. EPR spin trapping experiments have shown that chelation of quercetin to copper significantly suppressed the formation of hydroxyl radicals in the Cu(II)-Fenton reaction. DNA damage experiments revealed a protective effect for quercetin, but only at higher stoichiometric ratios of quercetin relative to copper. DNA protective effect of quercetin against ROS attack was described by two mechanisms. The first mechanism lies in suppressed formation of ROS due to the decreased catalytic action of copper in the Fenton reaction, as a consequence of its chelation and direct scavenging of ROS by free quercetin. Since the Cu-quercetin complex intercalates into DNA, the second mechanism was attributed to a suppressed intercalating ability of the Cu-quercetin complex due to the mildly intercalating free quercetin into DNA, thus creating a protective wall against stronger intercalators. Copyright © 2017 Elsevier Ltd. All rights reserved.

Thermodynamics of the complex formation of copper(II) with L-phenylalanine in aqueous ethanol solutions

NASA Astrophysics Data System (ADS)

Burov, D. M.; Ledenkov, S. F.; Vandyshev, V. N.

2013-05-01

Constants of the acid dissociation and complexation of L-phenylalanine (HPhe) with copper(II) ions are determined by potentiometry in aqueous ethanol solutions containing 0 to 0.7 molar fraction of alcohol. Changes in the Gibbs energy for the transfer from water to a binary solvent of L-phenylalanine, Phe- anion, and [CuPhe]+ complex are calculated. It is found that the weakening of solvation of the ligand donor groups in solvents with high ethanol contents is accompanied by an increase in the stability of [CuPhe]+ complex.

Structural influence in the interaction of cysteine with five coordinated copper complexes: Theoretical and experimental studies

NASA Astrophysics Data System (ADS)

Huerta-Aguilar, Carlos Alberto; Thangarasu, Pandiyan; Mora, Jesús Gracia

2018-04-01

Copper complexes of N,N,N‧,N‧-tetrakis(pyridyl-2-ylmethyl)-1,2-diaminoethane (L1) and N,N,N‧,N‧-tetrakis(pyridyl-2-ylmethyl)-1,3-diaminopropane (L2) prepared were characterized completely by different analytical methods. The X-structure of the complexes shows that Cu(II) presents in trigonal bi-pyramidal (TBP) geometry, consisting with the electronic spectra where two visible bands corresponding to five coordinated structure were observed. Thus TD-DFT was used to analyze the orbital contribution to the electronic transitions for the visible bands. Furthermore, the interaction of cysteine with the complexes was spectrally studied, and the results were explained through DFT analysis, observing that the geometrical parameters and oxidation state of metal ions play a vital role in the binding of cysteine with copper ion. It appears that the TBP structure is being changed into octahedral geometry during the addition of cysteine to the complexes as two bands (from complex) is turned to a broad band in visible region, signifying the occupation of cysteine molecule at sixth position of octahedral geometry. In the molecular orbital analysis, the existence of a strong overlapping of HOMOs (from cysteine) with LUMOs of Cu ion was observed. The total energy of the systems calculated by DFT shows that cysteine binds favorably with copper (I) than that with Cu(II).

Polynuclear Hydroxido-Bridged Complexes of Platinum(IV) with Terminal Nitrato Ligands.

PubMed

Vasilchenko, Danila; Berdugin, Semen; Tkachev, Sergey; Baidina, Iraida; Romanenko, Galina; Gerasko, Olga; Korenev, Sergey

2015-05-18

For the first time the polynuclear hydroxido-bridged platinum(IV) nitrato complexes with nuclearity higher than two were isolated from nitric acid solutions of [Pt(H2O)2(OH)4] and crystallized as supramolecular compounds of macrocyclic cavitands cucurbit[n]uril (CB[n], n = 6,8) and 18-crown-6 ether: [Pt4(μ3-OH)2(μ2-OH)4(NO3)10]·CB[6]·25H2O (I), [Pt6(μ3-OH)4(μ2-OH)6(NO3)12](NO3)2·CB[8]·50H2O (II), and [H3O⊂18-crown-6]2[Pt2(μ2-OH)2(NO3)8][Pt4(μ3-OH)2(μ2-OH)4(NO3)10] (III). The isolation of the compounds in the single crystalline state allows the determination of the structure of the tetranuclear and hexanuclear complexes [Pt4(μ3-OH)2(μ2-OH)4(NO3)10] and [Pt6(μ3-OH)4(μ2-OH)6(NO3)12](2+), which have been previously unknown in the solid state. Stability of Ptx(OH)y cores of the polynuclear nitrato complexes toward alkaline hydrolysis was verified by (195)Pt NMR spectroscopy. Analysis of (195)Pt NMR spectra of the compound III reveals that addition of every Pt(μ-OH)2Pt ring results in ∼260 ppm downfield shift relative to the mononuclear form, which allows the prediction of signal positions for complexes of higher nuclearity.

Nitric oxide donors or nitrite counteract copper-[dithiocarbamate](2)-mediated tumor cell death and inducible nitric oxide synthase down-regulation: possible role of a nitrosyl-copper [dithiocarbamate](2) complex.

PubMed

Rhenals, Maricela Viola; Strasberg-Rieber, Mary; Rieber, Manuel

2010-02-25

In contrast to other metal-dithiocarbamate [DEDTC] complexes, the copper-DEDTC complex is highly cytotoxic, inducing oxidative stress, preferentially in tumor cells. Because nitric oxide (NO) forms adducts with Cu[DEDTC](2), we investigated whether NO donors like S-nitroso-N-acetyl penicillamine (SNAP) or sodium nitroprusside (SNP), and nitrite, a NO decomposition product, modulate Cu[DEDTC](2) cytotoxicity against human tumor cells. We show that apoptosis-associated PARP cleavage and inducible nitric oxide synthase (iNOS) down-regulation induced by nanomolar Cu[DEDTC](2), are counteracted by 50 muM SNAP, SNP, or CoCl(2), an inducer of hypoxia and NO signaling. Nitrite was stochiometrically effective in antagonizing Cu[DEDTC](2) cytotoxicity and inducing shifts in the absorption spectrum of the binary complex in the 280 and 450 nm regions. Subtoxic concentrations of Cu[DEDTC](2) became lethal when tumor cells were pretreated with c-PTIO, a membrane-impermeable scavenger for extracellular NO. Our results suggest that: (a) reactive oxygen species induced by Cu[DEDTC](2) are scavenged by nitrite released from NO, (b) the extent of lethality of Cu[DEDTC](2) is dependent on the reciprocal formation of an inactive ternary Cu[DEDTC](2)NO copper-nitrosyl complex.

Synthesis, spectroscopy, magnetic and redox behaviors of copper(II) complexes with tert-butylated salen type ligands bearing bis(4-aminophenyl)ethane and bis(4-aminophenyl)amide backbones.

PubMed

Kasumov, Veli T; Yerli, Yusuf; Kutluay, Aysegul; Aslanoglu, Mehmet

2013-03-01

New salen type ligands, N,N'-bis(X-3-tert-butylsalicylidene)-4,4'-ethylenedianiline [(X=H (1), 5-tert-butyl (2)] and N,N'-bis(X-3-tert-butylsalicylidene)-4,4'-amidedianiline [X=H (3), 5-tert (4)] and their copper(II) complexes 5-8, have been synthesized. Their spectroscopic (IR, (1)H NMR, UV/vis, ESR) properties, as well as magnetic and redox-reactivity behavior are reported. IR spectra of 7 and 8 indicate the coordination of amide oxygen atoms of 3 and 4 ligands to Cu(II). The solid state ESR spectra of 5-8 exhibits less informative exchange narrowed isotropic or anisotropic signals with weak unresolved low field patterns. The magnetic moments of 5 (2.92 μ(B) per Cu(II)) and 6 (2.79 μ(B) per Cu(II)) are unusual for copper(II) complexes and considerably higher than those for complexes 7 and 8. Cryogenic measurements (300-10 K) show weak antiferromagnetic exchange interactions between the copper(II) centers in complexes 6 and 8. The results of electrochemical and chemical redox-reactivity studies are discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

Structural characterization of two solvates of a luminescent copper(II) bis­(pyridine)-substituted benzimidazole complex

PubMed Central

DeStefano, Matthew R.; Lewis, Robert A.

2017-01-01

Copper(II) complexes of benzimidazole are known to exhibit biological activity that makes them of inter­est for chemotherapeutic and other pharmaceutical uses. The complex bis­(acetato-κO){5,6-dimethyl-2-(pyridin-2-yl)-1-[(pyridin-2-yl)meth­yl]-1H-benzimidazole-κ2 N 2,N 3}copper(II), has been prepared. The absorption spectrum has features attributed to intra­ligand and ligand-field transitions and the complex exhibits ligand-centered room-temperature luminescence in solution. The aceto­nitrile monosolvate, [Cu(C2H3O2)2(C20H18N4)]·C2H3N (1), and the ethanol hemisolvate, [Cu(C2H3O2)2(C20H18N4)]·0.5C2H6O (2), have been structurally characterized. Compound 2 has two copper(II) complexes in the asymmetric unit. In both 1 and 2, distorted square-planar N2O2 coordination geometries are observed and the Cu—N(Im) bond distance is slightly shorter than the Cu—N(py) bond distance. Inter­molecular π–π inter­actions are found in 1 and 2. A weak C—H⋯π inter­action is observed in 1. PMID:29152336

A ruthenium(II) complex as turn-on Cu(II) luminescent sensor based on oxidative cyclization mechanism and its application in vivo

NASA Astrophysics Data System (ADS)

Zhang, Yunfei; Liu, Zonglun; Yang, Kui; Zhang, Yi; Xu, Yongqian; Li, Hongjuan; Wang, Chaoxia; Lu, Aiping; Sun, Shiguo

2015-02-01

Copper ions play a vital role in a variety of fundamental physiological processes not only in human beings and plants, but also for extensive insects and microorganisms. In this paper, a novel water-soluble ruthenium(II) complex as a turn-on copper(II) ions luminescent sensor based on o-(phenylazo)aniline was designed and synthesized. The azo group would undergo a specific oxidative cyclization reaction with copper(II) ions and turn into high luminescent benzotriazole, triggering significant luminescent increasements which were linear to the concentrations of copper(II) ions. The sensor distinguished by its high sensitivity (over 80-fold luminescent switch-on response), good selectivity (the changes of the emission intensity in the presence of other metal ions or amino acids were negligible) and low detection limit (4.42 nM) in water. Moreover, the copper(II) luminescent sensor exhibited good photostability under light irradiation. Furthermore, the applicability of the proposed sensor in biological samples assay was also studied and imaged copper(II) ions in living pea aphids successfully.

Rapid determination of trace copper in animal feed based on micro-plate colorimetric reaction and statistical partitioning correction.

PubMed

Niu, Yiming; Wang, Jiayi; Zhang, Chi; Chen, Yiqiang

2017-04-15

The objective of this study was to develop a micro-plate based colorimetric assay for rapid and high-throughput detection of copper in animal feed. Copper ion in animal feed was extracted by trichloroacetic acid solution and reduced to cuprous ion by hydroxylamine. The cuprous ion can chelate with 2,2'-bicinchoninic acid to form a Cu-BCA complex which was detected with high sensitivity by micro-plate reader at 354nm. The whole assay procedure can be completed within 20min. To eliminate matrix interference, a statistical partitioning correction approach was proposed, which makes the detection of copper in complex samples possible. The limit of detection was 0.035μg/mL and the detection range was 0.1-10μg/mL of copper in buffer solution. Actual sample analysis indicated that this colorimetric assay produced results consistent with atomic absorption spectrometry analysis. These results demonstrated that the developed assay can be used for rapid determination of copper in animal feed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ultra-deep oxidation and exotic copper formation at the late pliocene boyongan and bayugo porphyry copper-gold deposits, surigao, philippines: Geology, mineralogy, paleoaltimetry, and their implications for Geologic, physiographic, and tectonic controls

USGS Publications Warehouse

Braxton, D.P.; Cooke, D.R.; Ignacio, A.M.; Rye, R.O.; Waters, P.J.

2009-01-01

The Boyongan and Bayugo porphyry copper-gold deposits are part of an emerging belt of intrusion-centered gold-rich deposits in the Surigao district of northeast Mindanao, Philippines. Exhumation and weathering of these Late Pliocene-age deposits has led to the development of the world's deepest known porphyry oxidation profile at Boyongan (600 m), and yet only a modest (30-70 m) oxidation profile at adjacent Bayugo. Debris flows, volcanic rocks, and fluviolacustrine sediments accumulating in the actively extending Mainit graben subsequently covered the deposits and preserved the supergene profiles. At Boyongan and Bayugo, there is a vertical transition from shallower supergene copper oxide minerals (malachite + azurite + cuprite) to deeper sulfide-stable assemblages (chalcocite ?? hypogene sulfides). This transition provides a time-integrated proxy for the position of the water table at the base of the saturated zone during supergene oxidation. Contours of the elevation of the paleopotentiometric surface based on this min- eralogical transition show that the thickest portions of the unsaturated zone coincided with a silt-sand matrix diatreme breccia complex at Boyongan. Within the breccia complex, the thickness of the unsaturated zone approached 600 in, whereas outside the breccia complex (e.g., at Bayugo), the thickness averaged 50 m. Contours of the paleopotentiometric surface suggest that during weathering, groundwater flowed into the breccia complex from the north, south, and east, and exited along a high permeability zone to the west. The high relief (>550 m) on the elevation of the paleopotentiometric surface is consistent with an environment of high topographic relief, and the outflow zone to the west of the breccia complex probably reflects proximity to a steep scarp intersecting the western breccia complex margin. Stable isotope paleoaltimetry has enabled estimation of the elevation of the land surface, which further constrains the physiographic setting during supergene oxidation. Isotopic measurements of oxygen in supergene kaolinite from Boyongan suggest that local paleometeoric water involved in weathering had a ??180 composition of approximately -5.7 per mil. At the latitude of the southern Philippines, this value corresponds to Pleistocene rain water condensing at elevations between 750 and 1,050 m above contemporary sea level, providing a maximum estimate for the surface elevation during weathering of the porphyry systems. Physiographic reconstuctions suggest that the deep oxidation profile at Boyongan formed in an environment of high topographic relief immediately east of a prominent (>550 m) escarpment. The high permeability contrast between the breccia complex and the surrounding wall rocks, coupled with the proximity of the breccia complex to the escarpment, led to a depressed groundwater table and a vertically extensive unsaturated zone in the immediate vicinity of Boyongan. This thick vadose zone and the low hypogene pyrite/copper sulfide ratios (0.6) at Boyongan promoted in situ oxidation of copper sulfides with only modest (<200 m) supergene remobilization of copper. In contrast, higher hypogene pyrite/chalcopyrite ratios (2.3) at Bayugo led to greater acid production during weathering and more complete leaching of copper above the base of oxidation. This process promoted significant (600 m) lateral dispersion of copper down the paleohydraulic gradient into the diatreme breccia comple, ultimately leading to the formation of an exotic copper deposit. ?? 2009 Society of Economices Geologists, Inc.

A study of the effects of phosphates on copper corrosion in drinking water: Copper release, electrochemical, and surface analysis approach

NASA Astrophysics Data System (ADS)

Kang, Young C.

The following work is the study to evaluate the impact of corrosion inhibitors on the copper metal in drinking water and to investigate the corrosion mechanism in the presence and absence of inhibitors. Electrochemical experiments were conducted to understand the effect of specific corrosion inhibitors in synthetic drinking water which was prepared with controlled specific water quality parameters. Water chemistry was studied by Inductively Coupled Plasma--Atomic Emission Spectroscopy (ICP--AES) to investigate the copper leaching rate with time. Surface morphology, crystallinity of corrosion products, copper oxidation status, and surface composition were characterized by various solid surface analysis methods, such as Scanning Electron Microscopy/Energy--Dispersive Spectrometry (SEM/EDS), Grazing-Incidence-angle X-ray Diffraction (GIXRD), X-ray Photoelectron Spectroscopy (XPS), and Time-of-Flight Secondary Ions Mass Spectrometry (ToF-SIMS). The purpose of the first set of experiments was to test various electrochemical techniques for copper corrosion for short term before studying a long term loop system. Surface analysis techniques were carried out to identify and study the corrosion products that form on the fresh copper metal surface when copper coupons were exposed to test solutions for 2 days of experiments time. The second phase of experiments was conducted with a copper pipe loop system in a synthetic tap water over an extended period of time, i.e., 4 months. Copper release and electrochemically measured corrosion activity profiles were monitored carefully with and without corrosion inhibitor, polyphosphate. A correlation between the copper released into the solution and the electrochemically measured corrosion activities was also attempted. To investigate corrosion products on the copper pipe samples, various surface analysis techniques were applied in this study. Especially, static mass spectra acquisition and element distribution mapping were carried out by ToF-SIMS. Dynamic SIMS provided shallow depth profile of corroded copper sample. The third set of the experiments was related to electrochemical noise (EN) measurement through copper coupons to pipes. Calculating corrosion rate of a metal and predicting exactly how long it lasts are problematic since the metal corrosion may be caused by combined corrosion types. Many other metals undergo not only uniform corrosion, but localized corrosion. Uniform corrosion may be conducive for copper pipe to prevent it from further severe corrosion and form passivated film, but localized corrosion causes pinhole leaks and limits the copper pipe applications. The objective of this set of experiment is to discuss the application of electrochemical noise approaches to drinking water copper corrosion problems. Specially, a fundamental description of EN is presented including a discussion of how to interpret the results and technique limitations. Although it was indicated with electrochemical analysis that the corrosion activity was affected by orthophosphate addition in the short-term test, no copper-phosphate complex or compound was found by copper surface characterization. Apparently, orthophosphate can inhibit corrosion by adsorption on the copper surface, but cannot form solid complexes with copper in such a short time, 2 days. When polyphosphate was added into recirculating copper pipe system, copper level increased and polarization resistance decreased. Greenish blue residue on the copper pipe was suspected as copper phosphate complex and corrosion inhibition mechanism was proposed.

Rapid microwave-assisted acid extraction of southern pine waste wood to remove metals from chromated copper arsenate (CCA) treatment

Treesearch

Chung-Yun Hse; Todd F. Shupe; Bin Yu

2013-01-01

Recovery of metals from chromated copper arsenate (CCA)-treated southern pine wood particles was investigated by extraction in a microwave reactor with binary combinations of acetic acid (AA), oxalic acid (OxA), and phosphoric acid (PhA). Use of OxA was not successful, as insoluble copper oxalate complexes impeded copper removal. The combination of OxA and AA also had...

Non-covalent interactions in 2-methylimidazolium copper(II) complex (MeImH)2[Cu(pfbz)4]: Synthesis, characterization, single crystal X-ray structure and packing analysis

NASA Astrophysics Data System (ADS)

Sharma, Raj Pal; Saini, Anju; Kumar, Santosh; Kumar, Jitendra; Sathishkumar, Ranganathan; Venugopalan, Paloth

2017-01-01

A new anionic copper(II) complex, (MeImH)2 [Cu(pfbz)4] (1) where, MeImH = 2-methylimidazolium and pfbz = pentafluorobenzoate has been isolated by reacting copper(II) sulfate pentahydrate, pentafluorobenzoic acid and 2-methylimidazole in ethanol: water mixture in 1:2:2 molar ratio. This complex 1 has been characterized by elemental analysis, thermogravimetric analysis, spectroscopic techniques (UV-Vis, FT-IR) and conductance measurements. The complex salt crystallizes in monoclinic crystal system with space group C2/c. Single crystal X-ray structure determination revealed the presence of discrete ions: [Cu(pfbz)4]2- anion and two 2-methylimidazolium cation (C4H7N2)+. The crystal lattice is stabilized by strong hydrogen bonding and F⋯F interactions between cationic-anionic and the anionic-anionic moieties respectively, besides π-π interactions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Hang; Ha, Emmeline; Donaldson, Robert P.

Native electrospray ionization (ESI) mass spectrometry (MS) is often used to monitor noncovalent complex formation between peptides and ligands. The relatively low throughput of this technique, however, is not compatible with extensive screening. Laser ablation electrospray ionization (LAESI) MS combined with ion mobility separation (IMS) can analyze complex formation and provide conformation information within a matter of seconds. Islet amyloid polypeptide (IAPP) or amylin, a 37-amino acid residue peptide, is produced in pancreatic beta-cells through proteolytic cleavage of its prohormone. Both amylin and its precursor can aggregate and produce toxic oligomers and fibrils leading to cell death in the pancreasmore » that can eventually contribute to the development of type 2 diabetes mellitus. The inhibitory effect of the copper(II) ion on amylin aggregation has been recently discovered, but details of the interaction remain unknown. Finding other more physiologically tolerated approaches requires large scale screening of potential inhibitors. In this paper, we demonstrate that LAESI-IMS-MS can reveal the binding stoichiometry, copper oxidation state, and the dissociation constant of human amylin–copper(II) complex. The conformations of hIAPP in the presence of copper(II) ions were also analyzed by IMS, and preferential association between the β-hairpin amylin monomer and the metal ion was found. The copper(II) ion exhibited strong association with the —HSSNN– residues of the amylin. In the absence of copper(II), amylin dimers were detected with collision cross sections consistent with monomers of β-hairpin conformation. When copper(II) was present in the solution, no dimers were detected. Thus, the copper(II) ions disrupt the association pathway to the formation of β-sheet rich amylin fibrils. Using LAESI-IMS-MS for the assessment of amylin–copper(II) interactions demonstrates the utility of this technique for the high-throughput screening of potential inhibitors of amylin oligomerization and fibril formation. Finally and more generally, this rapid technique opens the door for high-throughput screening of potential inhibitors of amyloid protein aggregation.« less

Equilibrium isotopic fractionation of copper during oxidation/reduction, aqueous complexation and ore-forming processes: Predictions from hybrid density functional theory

NASA Astrophysics Data System (ADS)

Sherman, David M.

2013-10-01

Copper exists as two isotopes: 65Cu (∼30.85%) and 63Cu (∼69.15%). The isotopic composition of copper in secondary minerals, surface waters and oxic groundwaters is 1-12‰ heavier than that of copper in primary sulfides. Changes in oxidation state and complexation should yield substantial isotopic fractionation between copper species but it is unclear to what extent the observed Cu isotopic variations reflect equilibrium fractionation. Here, I calculate the reduced partition function ratios for chalcopyrite (CuFeS2), cuprite (Cu2O), tenorite (CuO) and aqueous Cu+, Cu+2 complexes using periodic and molecular hybrid density functional theory to predict the equilibrium isotopic fractionation of Cu resulting from oxidation of Cu+ to Cu+2 and by complexation of dissolved Cu. Among the various copper(II) complexes in aqueous environments, there is a significant (1.3‰) range in the reduced partition function ratios. Oxidation and congruent dissolution of chalcopyrite (CuFeS2) to dissolved Cu+2 (as Cu(H2O)5+2) yields 65-63δ(Cu+2-CuFeS2) = 3.1‰ at 25 °C; however, chalcopyrite oxidation/dissolution is incongruent so that the observed isotopic fractionation will be less. Secondary precipitation of cuprite (Cu2O) would yield further enrichment of dissolved 65Cu since 65-63δ(Cu+2-Cu2O) is 1.2‰ at 25 °C. However, precipitation of tenorite (CuO) will favor the heavy isotope by +1.0‰ making dissolved Cu isotopically lighter. These are upper-limit estimates for equilibrium fractionation. Therefore, the extremely large (9‰) fractionations between dissolved Cu+2 (or Cu+2 minerals) and primary Cu+ sulfides observed in supergene environments must reflect Rayleigh (open-system) or kinetic fractionation. Finally the previously proposed (Asael et al., 2009) use of δ65Cu in chalcopyrite to estimate the oxidation state of fluids that transported Cu in stratiform sediment-hosted copper deposits is refined.

Molecular structure, spectroscopic studies, and coppersbnd oxygen bond strength of α-methyl and α-ethyl derivatives of copper (II) acetylacetonate; Experimental and theoretical approach

NASA Astrophysics Data System (ADS)

Seyedkatouli, Seyedabdollah; Vakili, Mohammad; Tayyari, Sayyed Faramarz; Afzali, Raheleh

2018-05-01

This paper presents a combined experimental and theoretical study on the Cusbnd O bond strength of copper (II) α-methylacetylacetonate, Cu(3-Meacac)2, and copper (II) α-ethylacetylacetonate, Cu(3-Etacac)2, complexes in comparison to that in copper (II) acetylacetonate, Cu(acac)2. For this purpose, the molecular structure, UV spectra, and complete vibrational assignment of target molecules were investigated by DFT, Natural Bond Orbital (NBO) theory, and Atoms-in-Molecules (AIM) analysis at the B3LYP/6-311G* level of theory. The mentioned results are compared with those in Cu(acac)2. Fourier transform-Raman, IR, and UV spectra of these complexes have been also recorded. A complete assignment of the observed band frequencies has been done. All theoretical and experimental spectroscopic results are consisting with a stronger metal-oxygen bond in Cu(3-Meacac)2 and Cu(3-Etacac)2 complexes compared with Cu(acac)2. In addition, these results confirm that there is no significant difference between the Cusbnd O bond strength of the Cu(3-Meacac)2 and Cu(3-Etacac)2 complexes.

Mineralogical Characterization of Copper Slag from Tongling Nonferrous Metals Group China

NASA Astrophysics Data System (ADS)

Chun, Tiejun; Ning, Chao; Long, Hongming; Li, Jiaxin; Yang, Jialong

2016-09-01

In this paper, the mineralogical characterization of typical copper slag supplied by the Tongling Nonferrous Metals Group China was performed based on x-ray fluorescence, x-ray diffraction, and scanning electron microscopy with energy dispersive spectroscopy. The results show that the dominant phases of the slag are fayalite, glassy substance and magnetite. The minor accessory phases consist of copper matte, metallic copper and other complex lead and zinc minerals. The contents of iron, copper, lead and zinc in copper slag are 40.21%, 0.79%, 0.24%, and 2.80%, respectively. The mineralogy of copper slag indicates that these valuable elements are difficult to recover by beneficiation processes due to the complicated occurrences. Instead, the pyro-metallurgical processes appear promising in recovering the valuable metals from copper slag.

Liver mitochondrial dysfunction and electron transport chain defect induced by high dietary copper in broilers.

PubMed

Yang, Fan; Cao, Huabin; Su, Rongsheng; Guo, Jianying; Li, Chengmei; Pan, Jiaqiang; Tang, Zhaoxin

2017-09-01

Copper is an important trace mineral in the diet of poultry due to its biological activity. However, limited information is available concerning the effects of high copper on mitochondrial dysfunction. In this study, 72 broilers were used to investigate the effects of high dietary copper on liver mitochondrial dysfunction and electron transport chain defect. Birds were fed with different concentrations [11, 110, 220, and 330 mg of copper/kg dry matter (DM)] of copper from tribasic copper chloride (TBCC). The experiment lasted for 60 d. Liver tissues on d 60 were subjected to histopathological observation. Additionally, liver mitochondrial function was recorded on d 12, 36, and 60. Moreover, a site-specific defect in the electron transport chain in liver mitochondria was also identified by using various chemical inhibitors of mitochondrial respiration. The results showed different degrees of degeneration, mitochondrial swelling, and high-density electrons in hepatocytes. In addition, the respiratory control ratio (RCR) and oxidative phosphorylation rate (OPR) in liver mitochondria increased at first and then decreased in high-dose groups. Moreover, hydrogen peroxide (H2O2) generation velocity in treated groups was higher than that in control group, which were magnified by inhibiting electron transport at Complex IV. The results indicated that high dietary copper could decline liver mitochondrial function in broilers. The presence of a site-specific defect at Complex IV in liver mitochondria may be responsible for liver mitochondrial dysfunction caused by high dietary copper. © 2017 Poultry Science Association Inc.

Discovery of a potent and highly specific β2 proteasome inhibitor from a library of copper complexes.

PubMed

Zhou, Tongliang; Cai, Yuanbo; Liang, Lei; Yang, Lingfei; Xu, Fengrong; Niu, Yan; Wang, Chao; Zhang, Jun-Long; Xu, Ping

2016-12-01

We reported the synthesis, characterization and biological activity of several copper(II) Schiff base complexes, which exhibit high proteasome inhibitory activities with particular selectivity of β 2 subunit. Structure-activity relationships information obtained from complex Na 2 [Cu(a4s1)] demonstrated that distinct bonding modes in β 2 and β 5 subunits determines its selectivity and potent inhibition for β 2 subunit. Copyright © 2016 Elsevier Ltd. All rights reserved.

A Molecular Copper Catalyst for Hydrogenation of CO­2 to Formate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zall, Christopher M.; Linehan, John C.; Appel, Aaron M.

2015-09-04

There is widespread interest in the hydrogenation of CO2 to energy-rich products such as formate. However, first-row transition metal complexes that catalyze the hydrogenation of CO2 to formate remain rare. Copper phosphine complexes are widely used in the reduction of organic substrates but have not previously been used as catalysts for the conversion of H2 and CO2 to formate. Here we demonstrate that the triphosphine-ligated copper(I) complex LCu(MeCN)PF6 is an active catalyst for CO2 hydrogenation in the presence of a suitable base. Screening of bases and studies of catalytic reactions by in operando spectroscopy revealed important and unusual roles formore » the base in promoting H2 activation and turnover.« less

Synthesis, structural characterization, superoxide dismutase and antimicrobial activities studies of copper (II) complexes with 2-(E)-(2-(2-aminoethylamino) methyl)-4-bromophenol and (19E, 27E)-N1, N2-bis (phenyl (pyridine-2-yl)-methylene)-ethane-1, 2-diamine as ligands

NASA Astrophysics Data System (ADS)

Choudhary, Mukesh; Patel, R. N.; Rawat, S. P.

2014-07-01

Three new copper (II) complexes, [Cu(L)(H2O)]ClO4 (1), [Cu(L1)(ClO4)]+ (2) and [Cu(L1)]2+ (3), where HL = 2-(E)-(2-(2-aminoethylamino)methyl)-4-bromophenol, L1 =(19E, 27E)-N1,N2-bis(phenyl(pyridine-2-yl)-methylene)-ethane-1, 2-diamine, have been synthesized and characterized by using various physic-chemical and spectroscopic methods. The solid-state structures of 1 and 2 were determined by single crystal X-ray crystallography. Infrared spectra, ligand field spectra and magnetic susceptibility measurements agree with the observed crystal structures. The molecular structure of copper complexes showed that the ligands occupies the basal plane of square pyramidal geometry with the H2O of 1 or the ClO4 of 2 occupying the remaining apical position. Complexes 1 and 2 crystallize in the monoclinic system of the space group P21/c, a = 10.5948(6)Å, b = 19.6164(11)Å, c = 8.6517(5)Å, α = 90°, β = 108.213(2)°, γ = 90° and Z = 4 for 1, a = 9.5019(3)Å, b = 11.3 801(3)Å, c = 25.3168(14)Å, α = 90°, β = 100.583(4)°, γ = 90°, and Z = 4 for 2. The synthesized Schiff base (HL/L1) was behaves as tetradentate ON3/N4 ligands with donor groups suitable placed for forming 2 or 3 five membered chelate rings. Copper (II) complexes display X-band EPR spectra in 100% DMSO at 77 K giving g|| > g⊥ > 2.0023 indicating dx2-y2 ground state. The half-wave potential values for Cu (II)/Cu (I) redox couple obtained in the reaction of the copper (II) complexes with molecular oxygen and superoxide radical (O2-) electronegated in DMSO are in agreement with the SOD-like activity of the copper (II) complexes. In vitro antimicrobial activities of the complexes against the two bacteria (Escherichia coli, Salmonella typhi) and the two fungi (Penicillium, Aspergillus sp.) have been investigated comparing with the Schiff base ligands.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Xin; Zhou, Pei; Zheng, Chunying

A copper complex ([Cu(py){sub 2}(L){sub 2}]·2CH{sub 3}OH){sub n} (HL=(E)-3-(3-hydroxyl-phenyl)-acrylic acid) (1) with acrylic acid ligand was synthesized and structurally analyzed by IR, elemental analysis, TGA and the single-crystal X-ray diffraction methods. It is the first time to find that phenolic hydroxyl of L coordinates to Cu(II). Complex 1 exhibits 1D chain by a double-bridge of ligands, and the 3D supramolecular framework in complex 1 is constructed by π–π stacking interactions and van der Waals Contacts among the 1D chains. The magnetic properties of complex 1 have been studied. - Graphical abstract: A copper complex based on (E)-3-(3-hydroxyl-phenyl)-acrylic acid in amore » novel coordinated way was synthesized and a ferromagnetic exchange interactions between neighboring Cu(II) ions has be achieved. - Highlights: • A new copper complex with acrylic acid ligand was synthesized and analyzed. • We find the phenolic hydroxyl of MCA ligand coordinates to metal ion firstly. • A ferromagnetic exchange interactions between Cu(II) ions has been achieved.« less

Luminescent Copper(I) Halide Butterfly Dimers Coordinated to [Au(CH3imCH2py)2]BF4 and [Au(CH3imCH2quin)2]BF4

DOE Office of Scientific and Technical Information (OSTI.GOV)

Catalano, V.; Moore, A; Shearer, J

2009-01-01

The coordination chemistry of copper(I) halides to the homoleptic, N-heterocyclic carbene Au(I) complexes [Au(CH{sub 3}imCH{sub 2}quin){sub 2}]BF{sub 4} and [Au(CH{sub 3}imCH{sub 2}py){sub 2}]BF{sub 4} was explored. The reaction of CuX (X = Cl, Br, I) with either [Au(CH{sub 3}imCH{sub 2}quin){sub 2}]BF{sub 4} or [Au(CH{sub 3}imCH{sub 2}py){sub 2}]BF{sub 4} produces trimetallic complexes containing Cu{sub 2}X{sub 2}-butterfly copper clusters coordinated to the two imine moieties. The triangular arrangement of the metals places the gold(I) center in close proximity ({approx}2.5-2.6 {angstrom}) to the centroid of the Cu-Cu vector. The Cu-Cu separations vary as a function of bridging halide with the shortest Cu-Cu separationsmore » of {approx}2.5 {angstrom} found in the iodo-complexes and the longest separations of 2.9 {angstrom} found in the bridging chloride complexes. In all six complexes the Au-Cu separations range from {approx}2.8 to 3.0 {angstrom}. In the absence of halides, the dimetallic complex [AuCu(CH{sub 3}imCH{sub 2}py){sub 2}(NCCH{sub 3}){sub 2}](BF{sub 4}){sub 2}, containing a long Au-Cu distance of {approx}4.72 {angstrom} is formed. Additionally, as the byproduct of the reaction of CuBr with [Au(CH{sub 3}imCH{sub 2}quin){sub 2}]BF{sub 4} the deep-red, dimetallic compound, AuCuBr{sub 2}(CH{sub 3}imCH{sub 2}quin){sub 2}, was isolated in very low yield. All of these complexes were studied by NMR spectroscopy, mass spectrometry, and the copper containing species were additionally characterized by X-ray crystallography. In solution the copper centers dissociate from the gold complexes, but as shown by XANES and EXAFS spectroscopy, at low temperature the Cu-Cu linkage is broken, and the individual copper(I) halides reposition themselves to opposite sides of the gold complex while remaining coordinated to one imine moiety. In the solid state all of the complexes are photoluminescent, though the nature of the excited state was not determined.« less

Visual Observation of Dissolution of Copper Ions from a Copper Electrode

ERIC Educational Resources Information Center

Ikemoto, Isao; Saitou, Kouichi

2013-01-01

During electrolysis, to visually observe the conversion of a metal to its cation, either the cation or its complex ion should have a distinct color while the electrolyte solution must be colorless and transparent. A demonstration is described in which copper is used as the electrodes and sodium polyacrylate (a superabsorbent polymer) solution is…

Novel octanuclear copper(I) metallomacrocycles and their transformation into hexanuclear 2-dimensional grids of copper(i) coordination polymers containing cyclodiphosphazanes, [(micro-NtBuP)2(NC4H8X)2] (X = NMe, O).

PubMed

Suresh, D; Balakrishna, Maravanji S; Mague, Joel T

2008-07-07

Novel octanuclear copper(I) macrocyclic complexes and hexanuclear 2-dimensional grid-like polymers containing [P(micro-NR)](2) scaffold in which the anionic moieties are trapped inside the cationic macrocyclic cavities are reported.

Discovery and development of microporous metal carboxylates.

PubMed

Mori, Wasuke; Sato, Tomohiko; Kato, Chika Nozaki; Takei, Tohru; Ohmura, Tetsushi

2005-01-01

We have found a form of copper(II) terephthalate that occluded an enormous amount of gases such as N2, Ar, O2, and Xe. Copper(II) terephthalate is the first metal complex found capable of adsorbing gases. This complex has opened a new field of adsorbent chemistry and is recognized as a leader in the construction of microporous metal complexes. In extending the route for the synthesis of microporous complexes, we obtained many new porous materials that are widely recognized as useful materials for applications in areas such as gas storage, molecular sieves, catalysis, inclusion complexes, and surface science. 2005 The Japan Chemical Journal Forum and Wiley Periodicals, Inc.

Rapid assessment of human amylin aggregation and its inhibition by copper(II) ions by laser ablation electrospray ionization mass spectrometry with ion mobility separation

DOE PAGES

Li, Hang; Ha, Emmeline; Donaldson, Robert P.; ...

2015-09-09

Native electrospray ionization (ESI) mass spectrometry (MS) is often used to monitor noncovalent complex formation between peptides and ligands. The relatively low throughput of this technique, however, is not compatible with extensive screening. Laser ablation electrospray ionization (LAESI) MS combined with ion mobility separation (IMS) can analyze complex formation and provide conformation information within a matter of seconds. Islet amyloid polypeptide (IAPP) or amylin, a 37-amino acid residue peptide, is produced in pancreatic beta-cells through proteolytic cleavage of its prohormone. Both amylin and its precursor can aggregate and produce toxic oligomers and fibrils leading to cell death in the pancreasmore » that can eventually contribute to the development of type 2 diabetes mellitus. The inhibitory effect of the copper(II) ion on amylin aggregation has been recently discovered, but details of the interaction remain unknown. Finding other more physiologically tolerated approaches requires large scale screening of potential inhibitors. In this paper, we demonstrate that LAESI-IMS-MS can reveal the binding stoichiometry, copper oxidation state, and the dissociation constant of human amylin–copper(II) complex. The conformations of hIAPP in the presence of copper(II) ions were also analyzed by IMS, and preferential association between the β-hairpin amylin monomer and the metal ion was found. The copper(II) ion exhibited strong association with the —HSSNN– residues of the amylin. In the absence of copper(II), amylin dimers were detected with collision cross sections consistent with monomers of β-hairpin conformation. When copper(II) was present in the solution, no dimers were detected. Thus, the copper(II) ions disrupt the association pathway to the formation of β-sheet rich amylin fibrils. Using LAESI-IMS-MS for the assessment of amylin–copper(II) interactions demonstrates the utility of this technique for the high-throughput screening of potential inhibitors of amylin oligomerization and fibril formation. Finally and more generally, this rapid technique opens the door for high-throughput screening of potential inhibitors of amyloid protein aggregation.« less

Manganese(II), iron(II), cobalt(II), and copper(II) complexes of an extended inherently chiral tris-bipyridyl cage.

PubMed

Perkins, David F; Lindoy, Leonard F; McAuley, Alexander; Meehan, George V; Turner, Peter

2006-01-17

Manganese(II), iron(II), cobalt(II), and copper(II) derivatives of two inherently chiral, Tris(bipyridyl) cages (L and L') of type [ML]-(PF(6))(2)(solvent)(n) and [FeL'](ClO(4))(2) are reported, where L is the hexa-tertiary butyl-substituted derivative of L'. These products were obtained by using the free cage and metal template procedures; the latter involved the reductive amination of the respective Tris-dialdehyde precursor complexes of iron(II), cobalt(II), or nickel(II). Electrochemical, EPR, and NMR studies have been used to probe the nature of the individual complexes. X-ray structures of the manganese(II), iron(II), and copper(II) complexes of L and the iron(II) complex of L' are presented; these are compared with the previously reported structures of the corresponding nickel(II) complex and metal-free cage (L). In each complex the metal cation occupies the cage's central cavity and is coordinated to six nitrogens from the three bipyridyl groups. The cations [MnL](2+) and [FeL](2+) are isostructural but both exhibit a different arrangement of the bound cage to that observed in the corresponding nickel(II) and copper(II) complexes. The latter have an exo-exo arrangement of the bridgehead nitrogen lone pairs, with the metal inducing a triple helical twist that extends approximately 22 A along the axial length of each complex. In contrast, [MnL](2+) and [FeL](2+) have their terminal nitrogen lone pairs directed endo, causing a significant change in the configuration of the bound ligand. In [FeL'](2+), the cage has both bridgehead nitrogen lone pairs orientated exo. Semiempirical calculations indicate that the observed endo-endo and exo-exo arrangements are of comparable energy.

High stability and biological activity of the copper(II) complexes of alloferon 1 analogues containing tryptophan.

PubMed

Kadej, Agnieszka; Kuczer, Mariola; Czarniewska, Elżbieta; Urbański, Arkadiusz; Rosiński, Grzegorz; Kowalik-Jankowska, Teresa

2016-10-01

Copper(II) complex formation processes between the alloferon 1 (Allo1) (HGVSGHGQHGVHG) analogues where the tryptophan residue is introducing in the place His residue H1W, H6W, H9W and H12W have been studied by potentiometric, UV-visible, CD and EPR spectroscopic, and MS methods. For all analogues of alloferon 1 complex speciation have been obtained for a 1:1 metal-to-ligand molar ratio and 2:1 of H1W because of precipitation at higher (2:1, 3:1 and 4:1) ratios. At physiological pH7.4 and a 1:1 metal-to-ligand molar ratio the tryptophan analogues of alloferon 1 form the CuH -1 L and/or CuH -2 L complexes with the 4N binding mode. The introduction of tryptophan in place of histidine residues changes the distribution diagram of the complexes formed with the change of pH and their stability constants compared to the respective substituted alanine analogues of alloferon 1. The CuH -1 L, CuH -2 L and CuH -3 L complexes of the tryptophan analogues are more stable from 1 to 5 log units in comparison to those of the alanine analogues. This stabilization of the complexes may result from cation(Cu(II))-π and indole/imidazole ring interactions. The induction of apoptosis in vivo, in Tenebrio molitor cells by the ligands and their copper(II) complexes at pH7.4 was studied. The biological results show that copper(II) ions in vivo did not cause any apparent apoptotic features. The most active were the H12W peptide and Cu(II)-H12W complex formed at pH7.4. Copyright © 2016 Elsevier Inc. All rights reserved.

A model for the CO-inhibited form of [NiFe] hydrogenase: synthesis of (CO)3Fe(μ-StBu)3Ni{SC6H3-2,6-(mesityl)2} and reversible CO addition at the Ni site

PubMed Central

Ohki, Yasuhiro; Yasumura, Kazunari; Ando, Masaru; Shimokata, Satoko; Tatsumi, Kazuyuki

2010-01-01

A [NiFe] hydrogenase model compound having a distorted trigonal-pyramidal nickel center, (CO)3Fe(μ-StBu)3Ni(SDmp), 1 (Dmp = C6H3-2,6-(mesityl)2), was synthesized from the reaction of the tetranuclear Fe-Ni-Ni-Fe complex [(CO)3Fe(μ-StBu)3Ni]2(μ-Br)2, 2 with NaSDmp at -40 °C. The nickel site of complex 1 was found to add CO or CNtBu at -40 °C to give (CO)3Fe(StBu)(μ-StBu)2Ni(CO)(SDmp), 3, or (CO)3Fe(StBu)(μ-StBu)2Ni(CNtBu)(SDmp), 4, respectively. One of the CO bands of 3, appearing at 2055 cm-1 in the infrared spectrum, was assigned as the Ni-CO band, and this frequency is comparable to those observed for the CO-inhibited forms of [NiFe] hydrogenase. Like the CO-inhibited forms of [NiFe] hydrogenase, the coordination of CO at the nickel site of 1 is reversible, while the CNtBu adduct 4 is more robust. PMID:20147622

Quantum Electron Tunneling in Respiratory Complex I1

PubMed Central

Hayashi, Tomoyuki; Stuchebrukhov, Alexei A.

2014-01-01

We have simulated the atomistic details of electronic wiring of all Fe/S clusters in complex I, a key enzyme in the respiratory electron transport chain. The tunneling current theory of many-electron systems is applied to the broken-symmetry (BS) states of the protein at the ZINDO level. One-electron tunneling approximation is found to hold in electron tunneling between the anti-ferromagnetic binuclear and tetranuclear Fe/S clusters with moderate induced polarization of the core electrons. Calculated tunneling energy is about 3 eV higher than Fermi level in the band gap of the protein, which supports that the mechanism of electron transfer is quantum mechanical tunneling, as in the rest of electron transport chain. Resulting electron tunneling pathways consist of up to three key contributing protein residues between neighboring Fe/S clusters. A distinct signature of the wave properties of electrons is observed as quantum interferences when multiple tunneling pathways exist. In N6a-N6b, electron tunnels along different pathways depending on the involved BS states, suggesting possible fluctuations of the tunneling pathways driven by the local protein environment. The calculated distance dependence of the electron transfer rates with internal water molecules included are in good agreement with a reported phenomenological relation. PMID:21495666

Regulation of the copper chaperone CCS by XIAP-mediated ubiquitination.

PubMed

Brady, Graham F; Galbán, Stefanie; Liu, Xuwen; Basrur, Venkatesha; Gitlin, Jonathan D; Elenitoba-Johnson, Kojo S J; Wilson, Thomas E; Duckett, Colin S

2010-04-01

In order to balance the cellular requirements for copper with its toxic properties, an elegant set of mechanisms has evolved to regulate and buffer intracellular copper. The X-linked inhibitor of apoptosis (XIAP) protein was recently identified as a copper-binding protein and regulator of copper homeostasis, although the mechanism by which XIAP binds copper in the cytosol is unclear. Here we describe the identification of the copper chaperone for superoxide dismutase (CCS) as a mediator of copper delivery to XIAP in cells. We also find that CCS is a target of the E3 ubiquitin ligase activity of XIAP, although interestingly, ubiquitination of CCS by XIAP was found to lead to enhancement of its chaperone activity toward its physiologic target, superoxide dismutase 1, rather than proteasomal degradation. Collectively, our results reveal novel links among apoptosis, copper metabolism, and redox regulation through the XIAP-CCS complex.

Copper Metallochaperones

PubMed Central

Robinson, Nigel J.; Winge, Dennis R.

2014-01-01

The current state of knowledge on how copper metallochaperones support the maturation of cuproproteins is reviewed. Copper is needed within mitochondria to supply the CuA and intramembrane CuB sites of cytochrome oxidase, within the trans-Golgi network to supply secreted cuproproteins and within the cytosol to supply superoxide dismutase 1 (Sod1). Subpopulations of copper-zinc superoxide dismutase also localize to mitochondria, the secretory system, the nucleus and, in plants, the chloroplast, which also requires copper for plastocyanin. Prokaryotic cuproproteins are found in the cell membrane and in the periplasm of gram-negative bacteria. Cu(I) and Cu(II) form tight complexes with organic molecules and drive redox chemistry, which unrestrained would be destructive. Copper metallochaperones assist copper in reaching vital destinations without inflicting damage or becoming trapped in adventitious binding sites. Copper ions are specifically released from copper metallochaperones upon contact with their cognate cuproproteins and metal transfer is thought to proceed by ligand substitution. PMID:20205585

Chlorine-induced assembly of a cationic coordination cage with a μ5-carbonato-bridged Mn(II)24 core.

PubMed

Xiong, Ke-Cai; Jiang, Fei-Long; Gai, Yan-Li; Yuan, Da-Qiang; Han, Dong; Ma, Jie; Zhang, Shu-Quan; Hong, Mao-Chun

2012-04-27

Chlorine caged in! The chlorine-induced assembly of six shuttlecock-like tetranuclear Mn(II) building blocks generated in situ based on p-tert-butylthiacalix[4]arene and facial anions gave rise to a novel truncated distorted octahedral cationic coordination cage with a μ(5)-carbonato-bridged Mn(II)(24) core. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polynuclear complexes of copper(I) halides: coordination chemistry and catalytic transformations of alkynes

NASA Astrophysics Data System (ADS)

Mykhalichko, B. M.; Temkin, Oleg N.; Mys'kiv, M. G.

2000-11-01

Characteristic features of the coordination chemistry of Cu(I) and mechanisms of catalytic conversions of alkynes in the CuCl-MCl-H2O-HC≡CR system (MCl is alkali metal or ammonium chloride or amine hydrochloride; R=H, CH2OH, CH=CH2, etc.) are analysed based on studies of the compositions and structures of copper(I) chloride (bromide) complexes, alkyne π-complexes and ethynyl organometallic polynuclear compounds formed in this system in solutions and in the crystalline state. The role of polynuclear complexes in various reactions of alkynes is discussed. The bibliography includes 149 references.

New highlights on degradation process of verdigris from easel paintings

NASA Astrophysics Data System (ADS)

Santoro, Carlotta; Zarkout, Karim; Le Hô, Anne-Solenn; Mirambet, François; Gourier, Didier; Binet, Laurent; Pagès-Camagna, Sandrine; Reguer, Solenn; Mirabaud, Sigrid; Le Du, Yann; Griesmar, Pascal; Lubin-Germain, Nadège; Menu, Michel

2014-03-01

Verdigris is a green copper organometallic pigment, widely used in paintings during the fifteenth and sixteenth centuries. With ageing, chromatic modifications like browning or darkening can be observed on those green painted layers. An original but crucial approach has been developed based on the characterization of a reference neutral verdigris pigment—anhydrous copper acetate—and model samples, made of verdigris and linseed oil. Samples have undergone artificial ageing (temperature, light) to reproduce the color change effect. They were analysed before and after accelerated ageing tests by a complementary set of classical techniques: colorimetry, electron paramagnetic resonance, X-ray absorption spectroscopy, and UV-visible absorption. Our experiments revealed that the incorporation of the verdigris pigment in linseed oil induces a transformation of the copper acetate bimetallic structure, with the formation of monomeric species. These monomers, however, are not directly responsible for the darkening. The chromatic alteration seems instead linked to the transient formation of Cu(I) in the copper complexes of the pigment/oil system. This formation could be initiated by ambient light absorption through ligand-to-metal charge transfer, which favors the decarboxylation of the copper complexes leading to the reduction of Cu(II) into Cu(I). Moreover, dioxygen can react with partially decarboxylated dimers to form peroxy-Cu dimer complexes that can be responsible for the darkening.

Sulfonato-imino copper(ii) complexes: fast and general Chan-Evans-Lam coupling of amines and anilines.

PubMed

Hardouin Duparc, V; Schaper, F

2017-10-14

Sulfonato-imine copper complexes with either chloride or triflate counteranions were prepared in a one-step reaction followed by anion-exchange. They are highly active in Chan-Evans-Lam couplings under mild conditions with a variety of amines or anilines, in particular with sterically hindered substrates. No optimization of reaction conditions other than time and/or temperature is required.

Copper-Mediated Fluorination of Arylboronate Esters. Identification of a Copper(III) Fluoride Complex

PubMed Central

Fier, Patrick S.; Luo, Jingwei; Hartwig, John F.

2013-01-01

A method for the direct conversion of arylboronate esters to aryl fluorides under mild conditions with readily available reagents is reported. Tandem reactions have also been developed for the fluorination of arenes and aryl bromides through aryl-boronate ester intermediates. Mechanistic studies suggest that this fluorination reaction occurs through facile oxidation of Cu(I) to Cu(III) followed by rate-limiting transmetallation of a bound arylboronate to Cu(III). Fast C-F reductive elimination is proposed to occur from an aryl-copper(III)-fluoride complex. Cu(III) intermediates have been generated independently and identified by NMR spectroscopy and ESI-MS. PMID:23384209

Extraction-spectrophotometric determination of traces of gold in copper in silver, lead, blister copper, copper concentrate and anode slime with 4,4'-bis(dimethylamino)-thiobenzophenone.

PubMed

Tsukahara, I

1977-10-01

A sensitive spectrophotometric method has been developed for the determination of gold in copper, silver, lead, blister copper, copper concentrate and anode slime. Optimal conditions have been established for the extraction and determination of gold. Gold is extracted as its bromo complex with tri-n-octylamine and determined photometrically with 4,4'-bis(dimethylamino)thiobenzophenone; the absorbance of the organic phase is measured at 540 nm and the apparent molar absorptivity is about 1.2 x 10(5) 1.mole(-1). cm(-1). As little as 0.1 or 0.2 ppm of gold in these materials can be determined.

Antiobesity, antioxidant and cytotoxicity activities of newly synthesized chalcone derivatives and their metal complexes.

PubMed

El Sayed Aly, Mohamed Ramadan; Abd El Razek Fodah, Hamadah Hamadah; Saleh, Sherif Yousef

2014-04-09

Four sets of rationally designed chalcones were prepared for evaluation of their antiobesity, antioxidant and cytotoxicity activities. These sets include nine oleoyl chalcones as mimics of oleoyl estrone, three monohydroxy chalcones (chalcone ligands), Schiff base-derived chalcones and four copper as well as zinc complexes. Oleoyl chalcones 4d, 4e and particularly 6a as an isosteric isomer of oleoyl estrone, were as active as Orlistat on weight loss and related metabolic parameters using male SD rats in vivo. Chalcone ligands 10a-c and Schiff base-derived chalcones 11 and 14a,b were weakly antioxidants, while, the copper and zinc complexes 15a-d were good antioxidants with zinc chelates 15b,d being more active than their copper analogues 15a,cin vitro. Compounds 10c and 14a showed good cytotoxicity activities as Doxorubicin against PC3 cancer cell line in vitro, while, the copper complex 15c showed promising activity with IC₅₀ value of 5.95 μM. The estimated IC₅₀ value for Doxorubicin was 8.7 μM. Chalcones 14a,b are bifunctional probes for potential investigations in cancer diagnosis and radiotherapy by complexation with Gd(3+) or metal radioisotopes followed by posttranslation of Shiga toxin B-subunits that target globotriosyl ceramide expressing cancer cells. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Spontaneous and Directional Bubble Transport on Porous Copper Wires with Complex Shapes in Aqueous Media.

PubMed

Li, Wenjing; Zhang, Jingjing; Xue, Zhongxin; Wang, Jingming; Jiang, Lei

2018-01-24

Manipulation of gas bubble behaviors is crucial for gas bubble-related applications. Generally, the manipulation of gas bubble behaviors generally takes advantage of their buoyancy force. It is very difficult to control the transportation of gas bubbles in a specific direction. Several approaches have been developed to collect and transport bubbles in aqueous media; however, most reliable and effective manipulation of gas bubbles in aqueous media occurs on the interfaces with simple shapes (i.e., cylinder and cone shapes). Reliable strategies for spontaneous and directional transport of gas bubbles on interfaces with complex shapes remain enormously challenging. Herein, a type of 3D gradient porous network was constructed on copper wire interfaces, with rectangle, wave, and helix shapes. The superhydrophobic copper wires were immersed in water, and continuous and stable gas films then formed on the interfaces. With the assistance of the Laplace pressure gradient between two bubbles, gas bubbles (including microscopic gas bubbles) in the aqueous media were subsequently transported, continuously and directionally, on the copper wires with complex shapes. The small gas bubbles always moved to the larger ones.

Copper chalcogenide clusters stabilized with ferrocene-based diphosphine ligands.

PubMed

Khadka, Chhatra B; Najafabadi, Bahareh Khalili; Hesari, Mahdi; Workentin, Mark S; Corrigan, John F

2013-06-17

The redox-active diphosphine ligand 1,1'-bis(diphenylphosphino)ferrocene (dppf) has been used to stabilize the copper(I) chalcogenide clusters [Cu12(μ4-S)6(μ-dppf)4] (1), [Cu8(μ4-Se)4(μ-dppf)3] (2), [Cu4(μ4-Te)(μ4-η(2)-Te2)(μ-dppf)2] (3), and [Cu12(μ5-Te)4(μ8-η(2)-Te2)2(μ-dppf)4] (4), prepared by the reaction of the copper(I) acetate coordination complex (dppf)CuOAc (5) with 0.5 equiv of E(SiMe3)2 (E = S, Se, Te). Single-crystal X-ray analyses of complexes 1-4 confirm the presence of {Cu(2x)E(x)} cores stabilized by dppf ligands on their surfaces, where the bidentate ligands adopt bridging coordination modes. The redox chemistry of cluster 1 was examined using cyclic voltammetry and compared to the electrochemistry of the free ligand dppf and the corresponding copper(I) acetate coordination complex 5. Cluster 1 shows the expected consecutive oxidations of the ferrocene moieties, Cu(I) centers, and phosphine of the dppf ligand.

Cytokinin oxidase from Phaseolus vulgaris callus tissues. Enhanced in vitro activity of the enzyme in the presence of copper-imidazole complexes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chatfield, J.M.; Armstrong, D.J.

1987-07-01

The effects of metal ions on cytokinin oxidase activity extracted from callus tissues of Phaseolus vulgaris L. cv Great Northern have been examined using an assay based on the oxidation of N/sup 6/-(..delta../sup 2/-isopentenyl)-adenine-2,8-/sup 3/H (i/sup 6/ Ade) to adenine (Ade). The addition of cupric ions to reaction mixtures containing imidazole buffer markedly enhanced cytokinin oxidase activity. In the presence of optimal concentrations of copper and imidazole, cytokinin oxidase activity was stimulated more than 20-fold. The effect was enzyme dependent, specific for copper, and observed only in the presence of imidazole. The substrate specificity of the copper-imidazole enhanced reaction, asmore » judged by substrate competition tests, was the same as that observed in the absence of copper and imidazole. Similarly, in tests involving DEAE-cellulose chromatography, elution profiles of cytokinin oxidase activity determined using a copper-imidazole enhanced assay were identical to those obtained using an assay without copper and imidazole. On the basis of these results, the addition of copper and imidazole to reaction mixtures used to assay for cytokinin oxidase activity is judged to provide a reliable and specific assay of greatly enhanced sensitivity for the enzyme. The mechanism by which copper and imidazole enhance cytokinin oxidase activity is not certain, but the reaction catalyzed by the enzyme was not inhibited by anaerobic conditions when these reagents were present. This observation suggests that copper-imidazole complexes are substituting for oxygen in the reaction mechanism by which cytokinin oxidase effects cleavage of the N/sup 6/-side chain of i/sup 6/ Ade.« less

Characterization and mechanism of copper biosorption by a highly copper-resistant fungal strain isolated from copper-polluted acidic orchard soil.

PubMed

Tu, Chen; Liu, Ying; Wei, Jing; Li, Lianzhen; Scheckel, Kirk G; Luo, Yongming

2018-06-22

In this paper, a highly copper-resistant fungal strain NT-1 was characterized by morphological, physiological, biochemical, and molecular biological techniques. Physiological response to Cu(II) stress, effects of environmental factors on Cu(II) biosorption, as well as mechanisms of Cu(II) biosorption by strain NT-1 were also investigated in this study. The results showed that NT-1 belonged to the genus Gibberella, which exhibited high tolerance to both acidic conditions and Cu(II) contamination in the environment. High concentrations of copper stress inhibited the growth of NT-1 to various degrees, leading to the decreases in mycelial biomass and colony diameter, as well as changes in morphology. Under optimal conditions (initial copper concentration: 200 mg L -1 , temperature 28 °C, pH 5.0, and inoculum dose 10%), the maximum copper removal percentage from solution through culture of strain NT-1 within 5 days reached up to 45.5%. The biosorption of Cu(II) by NT-1 conformed to quasi-second-order kinetics and Langmuir isothermal adsorption model and was confirmed to be a monolayer adsorption process dominated by surface adsorption. The binding of NT-1 to Cu(II) was mainly achieved by forming polydentate complexes with carboxylate and amide group through covalent interactions and forming Cu-nitrogen-containing heterocyclic complexes via Cu(II)-π interaction. The results of this study provide a new fungal resource and key parameters influencing growth and copper removal capacity of the strain for developing an effective bioremediation strategy for copper-contaminated acidic orchard soils.

Form and toxicity of copper released into marine systems from ...

EPA Pesticide Factsheets

The fate and effects of pristine engineered nanomaterials (ENMs) in simplified systems have been widely studied; however, little is known about the potential release and impact of ENMs from consumer goods, especially lumber that has been treated with micronized copper. Micronized copper solutions contain copper complexes predominately in the 10-700 nm size range, and are used in lumber to prevent microbial degradation and fouling. In this work, the goal was to determine the rate, concentration, and form of copper released from commercially available pressure treated lumber samples (blocks and sawdust) exposed to an aqueous system. Lumber tested included Southern Yellow Pine (SYP) treated with micronized copper azole (MCA) at 0.96 and 2.4 Kg/m3, alkaline copper quaternary (ACQ) at 0.30 and 9.6 Kg/m3, and chromated copper arsenate (CCA) at 40 Kg/m3. Of the different chemical treatments, only MCA included nano- and micro-sized copper complexes. The experimental system included wood cubes cut from the outer 2 cm surface of the lumber or the equivalent mass (4 g) of sawdust submerged in 250 mL of media (0, 1, 10, and 30 ppt filtered natural seawater) in polyethylene bottles, and mixed on a shaker table at 120 rpm. Water samples were taken at 8 hours, and on days 1, 2, 7, 14, and 28 for the blocks and days 1, 2, 3, 7, 17, and 28 for the sawdust. Subsamples included unfiltered water (defined as 0.45 µm - filtered water for the sawdust), and water filtered through a 0.

Potentiometric and DFT studies of Cu(II) complexes with glycylglycine and methionine of interest for the brain chemistry

NASA Astrophysics Data System (ADS)

Vilhena, Felipe S.; Felcman, Judith; Szpoganicz, Bruno; Miranda, Fabio S.

2017-01-01

A large number of copper (II) complexes have been used as mimetic models for metalloproteins and metalloenzymes. Due to the lack of structural information about copper (II) complexes in aqueous solution, the coordination environment of this metal is not well established. In this work, pKa values of the complexes in the Cu:GlyGly, Cu:Met and Cu:GlyGly:Met systems were calculated by potentiometric titration at 25 °C and ionic strength of 0.1 mol L-1. The coordination modes of the ligands were explored for the main hydrolytic species throught RI-PBE/def2-SVP/COSMO level. In the Cu:GlyGly system, DFT results indicated that the NamineNpept coordination of dipeptide is 2.1 kcal mol-1 more stable than the tridentate NamineNpeptOcarboxy coordination moiety. The deprotonation of the peptide nitrogen is 13.7 kcal mol-1 more favorable than the hydrolysis of the water molecule coordinated to the metal. In the Cu:GlyGly:Met system, the sulfur atom does not belong to the copper (II) coordination sphere. Once the copper ion is incorporated into peptides, another ligand as methionine could bind to this system and carry an antioxidant site to different brain regions.

The sequential injection system with adsorptive stripping voltammetric detection.

PubMed

Kubiak, W W; Latonen, R M; Ivaska, A

2001-03-16

Two sequential injection systems have been developed for adsorptive stripping voltammetric measurement. One is for substances adsorbing at mercury, e.g. riboflavin. In this case, a simple arrangement with only sample aspiration is needed. Reproducibility was 3% and detection limit 0.07 muM. The measuring system was applied to determination of riboflavin in vitamin pills and to study the photodegradation process of riboflavin in aqueous solutions. In the second case, metal ions were determined. They have to be complexed before deposition on the mercury surface. Thus, both the sample and the ligand have to be aspirated in the system. In this case, the reproducibility was approximately 6% and the detection limit <0.1 ppm for cadmium, lead and copper when complexation with oxine was used. Dimethylglyoxime was used in determination of nickel and cobalt and nioxime complexes were used in determination of nickel and copper. With these complexing agents, the reproducibility was the same as with oxine, but the metals could be determined at concentrations lower than 0.01 ppm. Application of two ligands in a SIA system with AdSV detection was also studied. Simultaneous determination of copper, lead, cadmium and cobalt was possible by using oxine and dimethylglyoxime. Copper and nickel were simultaneously determined by using dimethylglyoxime and nioxime.

New technique for heterogeneous vapor-phase synthesis of nanostructured metal layers from low-dimensional volatile metal complexes

NASA Astrophysics Data System (ADS)

Badalyan, A. M.; Bakhturova, L. F.; Kaichev, V. V.; Polyakov, O. V.; Pchelyakov, O. P.; Smirnov, G. I.

2011-09-01

A new technique for depositing thin nanostructured layers on semiconductor and insulating substrates that is based on heterogeneous gas-phase synthesis from low-dimensional volatile metal complexes is suggested and tried out. Thin nanostructured copper layers are deposited on silicon and quartz substrates from low-dimensional formate complexes using a combined synthesis-mass transport process. It is found that copper in layers thus deposited is largely in a metal state (Cu0) and has the form of closely packed nanograins with a characteristic structure.

Isolation of a new two-dimensional honeycomb carbonato-bridged copper(II) complex exhibiting long-range ferromagnetic ordering.

PubMed

Majumder, Arpi; Choudhury, Chirantan Roy; Mitra, Samiran; Rosair, Georgina M; El Fallah, M Salah; Ribas, Joan

2005-04-28

Atmospheric CO2 fixation by an aqueous solution containing Cu(ClO4)2.6H2O and 4-aminopyridine (4-apy) yields a novel example of a two-dimensional mu3-CO3 bridged copper(II) complex {[Cu(4-apy)2]3(mu3-CO3)2(ClO4)2.(1/2)CH3OH}n that has been characterized by IR, UV and X-ray crystallography; preliminary magnetic measurements show that complex exhibits long-range ordered ferromagnetic coupling.

The Myxococcus xanthus two-component system CorSR regulates expression of a gene cluster involved in maintaining copper tolerance during growth and development.

PubMed

Sánchez-Sutil, María Celestina; Pérez, Juana; Gómez-Santos, Nuria; Shimkets, Lawrence J; Moraleda-Muñoz, Aurelio; Muñoz-Dorado, José

2013-01-01

Myxococcus xanthus is a soil-dwelling member of the δ-Proteobacteria that exhibits a complex developmental cycle upon starvation. Development comprises aggregation and differentiation into environmentally resistant myxospores in an environment that includes fluctuations in metal ion concentrations. While copper is essential for M. xanthus cells because several housekeeping enzymes use it as a cofactor, high copper concentrations are toxic. These opposing effects force cells to maintain a tight copper homeostasis. A plethora of paralogous genes involved in copper detoxification, all of which are differentially regulated, have been reported in M. xanthus. The use of in-frame deletion mutants and fusions with the reporter gene lacZ has allowed the identification of a two-component system, CorSR, that modulates the expression of an operon termed curA consisting of nine genes whose expression slowly increases after metal addition, reaching a plateau. Transcriptional regulation of this operon is complex because transcription can be initiated at different promoters and by different types of regulators. These genes confer copper tolerance during growth and development. Copper induces carotenoid production in a ΔcorSR mutant at lower concentrations than with the wild-type strain due to lack of expression of a gene product resembling subunit III of cbb3-type cytochrome c oxidase. This data may explain why copper induces carotenoid biosynthesis at suboptimal rather than optimal growth conditions in wild-type strains.

The Myxococcus xanthus Two-Component System CorSR Regulates Expression of a Gene Cluster Involved in Maintaining Copper Tolerance during Growth and Development

PubMed Central

Sánchez-Sutil, María Celestina; Pérez, Juana; Gómez-Santos, Nuria; Shimkets, Lawrence J.; Moraleda-Muñoz, Aurelio; Muñoz-Dorado, José

2013-01-01

Myxococcus xanthus is a soil-dwelling member of the δ–Proteobacteria that exhibits a complex developmental cycle upon starvation. Development comprises aggregation and differentiation into environmentally resistant myxospores in an environment that includes fluctuations in metal ion concentrations. While copper is essential for M. xanthus cells because several housekeeping enzymes use it as a cofactor, high copper concentrations are toxic. These opposing effects force cells to maintain a tight copper homeostasis. A plethora of paralogous genes involved in copper detoxification, all of which are differentially regulated, have been reported in M. xanthus. The use of in-frame deletion mutants and fusions with the reporter gene lacZ has allowed the identification of a two-component system, CorSR, that modulates the expression of an operon termed curA consisting of nine genes whose expression slowly increases after metal addition, reaching a plateau. Transcriptional regulation of this operon is complex because transcription can be initiated at different promoters and by different types of regulators. These genes confer copper tolerance during growth and development. Copper induces carotenoid production in a ΔcorSR mutant at lower concentrations than with the wild-type strain due to lack of expression of a gene product resembling subunit III of cbb3-type cytochrome c oxidase. This data may explain why copper induces carotenoid biosynthesis at suboptimal rather than optimal growth conditions in wild-type strains. PMID:23874560

Selective flotation-spectrophotometric determination of trace copper(II) in natural waters, human blood and drug samples using phenanthraquinone monophenylthiosemicarbazone.

PubMed

Khalifa, M E; Akl, M A; Ghazy, S E

2001-06-01

Copper(II) forms 1:1 and 1:2 intense red complexes with phenanthraquinone monophenylthiosemicarbazone (PPT) at pH 3-3.5 and > or =6.5, respectively. These complexes exhibit maximal absorbance at 545 and 517 nm, the molar absorptivity being 2.3 x 10(4) and 4.8 x 10(4) l mol(-1) cm(-1), respectively. However, the 1:1 complex was quantitatively floated with oleic acid (HOL) surfactant in the pH range 4.5-5.5, providing a highly selective and sensitive procedure for the spectrophotometric determination of CuII. The molar absorptivity of the floated Cu-PPT complex was 1.5 x 10(5) l mol)(-1) cm(-1). Beer's law was obeyed over the range 3-400 ppb at 545 nm. The analytical parameters affecting the flotation process and hence the determination of copper traces were reported. Also, the structure of the isolated solid complex and the mechanism of flotation were suggested. Moreover, the procedure was successfully applied to the analysis of CuII in natural waters, serum blood and some drug samples.

Surfactant-free electrodeposition of reduced graphene oxide/copper composite coatings with enhanced wear resistance

NASA Astrophysics Data System (ADS)

Mai, Y. J.; Zhou, M. P.; Ling, H. J.; Chen, F. X.; Lian, W. Q.; Jie, X. H.

2018-03-01

How to uniformly disperse graphene sheets into the electrolyte is one of the main challenges to synthesize graphene enhanced nanocomposites by electrodeposition. A surfactant-free colloidal solution comprised of copper (II)-ethylene diamine tetra acetic acid ([CuIIEDTA]2-) complexes and graphene oxide (GO) sheets is proposed to electrodeposit reduced graphene oxide/copper (RGO/Cu) composite coatings. Anionic [CuIIEDTA]2- complexes stably coexist with negatively charged GO sheets due to the electrostatic repulsion between them, facilitating the electrochemical reduction and uniform dispersion of GO sheets into the copper matrix. The RGO/Cu composite coatings are well characterized by XRD, Raman, SEM and XPS. Their tribological behavior as a function of RGO content in composite coatings and normal loads are investigated. Also the chemical composition and topography of the wear tracks for the composite coatings are analyzed to deduce the lubricating and anti-wear mechanism of RGO/Cu composite coatings.

Trialkylphosphine-stabilized copper(I) gallium(III) phenylchalcogenolate complexes: crystal structures and generation of ternary semiconductors by thermolysis.

PubMed

Kluge, Oliver; Krautscheid, Harald

2012-06-18

A series of organometallic trialkylphosphine-stabilized copper gallium phenylchalcogenolate complexes [(R(3)P)(m)Cu(n)Me(2-x)Ga(EPh)(n+x+1)] (R = Me, Et, (i)Pr, (t)Bu; E = S, Se, Te; x = 0, 1) has been prepared and structurally characterized by X-ray diffraction. From their molecular structures three groups of compounds can be distinguished: ionic compounds, ring systems, and cage structures. All these complexes contain one gallium atom bound to one or two methyl groups, whereas the number of copper atoms, and therefore the nuclearity of the complexes, is variable and depends mainly on size and amount of phosphine ligand used in synthesis. The Ga-E bonds are relatively rigid, in contrast to flexible Cu-E bonds. The lengths of the latter are controlled by the coordination number and steric influences. The Ga-E bond lengths depend systematically on the number of methyl groups bound to the gallium atom, with somewhat shorter bonds in monomethyl compounds compared to dimethyl compounds. Quantum chemical computations reproduce this trend and show furthermore that the rotation of one phenyl group around the Ga-E bond is a low energy process with two distinct minima, corresponding to two different conformations found experimentally. Mixtures of different types of chalcogen atoms on molecular scale are possible, and then ligand exchange reactions in solution lead to mixed site occupation. In thermogravimetric studies the complexes were converted into the ternary semiconductors CuGaE(2). The thermolysis reaction is completed at temperatures between 250 and 400 °C, typically with lower temperatures for the heavier chalcogens. Because of significant release of Me(3)Ga during the thermolysis process, and especially in case of copper excess in the precursor complexes, binary copper chalcogenides are obtained as additional thermolysis products. Quaternary semiconductors can be obtained from mixed chalcogen precursors.

Copper transport and regulation in Schizosaccharomyces pombe

PubMed Central

Beaudoin, Jude; Ekici, Seda; Daldal, Fevzi; Ait-Mohand, Samia; Guérin, Brigitte; Labbé, Simon

2016-01-01

The fission yeast Schizosaccharomyces pombe has been successfully used as a model to gain fundamental knowledge in understanding how eukaryotic cells acquire copper during vegetative growth. These studies have revealed the existence of a heteromeric Ctr4–Ctr5 plasma membrane complex that mediates uptake of copper within the cells. Furthermore, additional studies have led to the identification of one of the first vacuolar copper transporters, Ctr6, as well as the copper-responsive Cuf1 transcription factor. Recent investigations have extended the use of S. pombe to elucidate new roles for copper metabolism in meiotic differentiation. For example, these studies have led to the discovery of Mfc1, which turned out to be the first example of a meiosis-specific copper transporter. Whereas copper-dependent transcriptional regulation of the Ctr family members is under the control of Cuf1 during mitosis or meiosis, meiosis-specific copper transporter Mfc1 is regulated by the recently discovered transactivator Mca1. It is foreseeable that identification of novel meiotic copper-related proteins will serve as stepping stones to unravel fundamental aspects of copper homoeostasis. PMID:24256274

Copper transport and regulation in Schizosaccharomyces pombe.

PubMed

Beaudoin, Jude; Ekici, Seda; Daldal, Fevzi; Ait-Mohand, Samia; Guérin, Brigitte; Labbé, Simon

2013-12-01

The fission yeast Schizosaccharomyces pombe has been successfully used as a model to gain fundamental knowledge in understanding how eukaryotic cells acquire copper during vegetative growth. These studies have revealed the existence of a heteromeric Ctr4-Ctr5 plasma membrane complex that mediates uptake of copper within the cells. Furthermore, additional studies have led to the identification of one of the first vacuolar copper transporters, Ctr6, as well as the copper-responsive Cuf1 transcription factor. Recent investigations have extended the use of S. pombe to elucidate new roles for copper metabolism in meiotic differentiation. For example, these studies have led to the discovery of Mfc1, which turned out to be the first example of a meiosis-specific copper transporter. Whereas copper-dependent transcriptional regulation of the Ctr family members is under the control of Cuf1 during mitosis or meiosis, meiosis-specific copper transporter Mfc1 is regulated by the recently discovered transactivator Mca1. It is foreseeable that identification of novel meiotic copper-related proteins will serve as stepping stones to unravel fundamental aspects of copper homoeostasis.

Selective Reduction of CO2 to a Formate Equivalent with Heterobimetallic Gold- - -Copper Hydride Complexes.

PubMed

Hicken, Alexandra; White, Andrew J P; Crimmin, Mark R

2017-11-20

A series of heterobimetallic complexes containing three-center, two-electron Au-H-Cu bonds have been prepared from addition of a parent gold hydride to a bent d 10 copper(I) fragment. These highly unusual heterobimetallic complexes represent a missing link in the widely investigated series of neutral and cationic coinage metal hydride complexes containing Cu-H-Cu and M-H-M + moieties (M=Cu, Ag). The well-defined heterobimetallic hydride complexes act as precatalysts for the conversion of CO 2 into HCO 2 Bpin with HBpin as the reductant. The selectivity of the heterobimetallic complexes for the catalytic production of a formate equivalent surpasses that of the parent monomeric Group 11 complexes. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Patterned low temperature copper-rich deposits using inkjet printing

NASA Astrophysics Data System (ADS)

Rozenberg, Gregor G.; Bresler, Eric; Speakman, Stuart P.; Jeynes, Chris; Steinke, Joachim H. G.

2002-12-01

A PZT piezoelectric ceramic research drop-on-demand inkjet print head operating in bend mode was used as a means of delivering a copper precursor, vinyltrimethylsilane copper (+1) hexafluoroacetylacetonate, in a controlled and placement accurate fashion. The reagent disproportionates at low temperature (<200 °C), to deposit copper on glass. These deposits are shown to be more than 90% copper by weight by electron probe microanalysis and microbeam Rutherford backscattering spectroscopy. Microscopy shows a deposit diameter and three-dimensional profile that suggests a complex deposition and conversion mechanism. Our findings represent an important step towards the manufacture of electronic devices by entirely nonlithographic means.

Effect of weathering on chromated copper arsenate (CCA) treated wood : leaching of metal salts and change in water repellency

Treesearch

R. Sam Williams; Stan Lebow; Patricia Lebow

2003-01-01

Wood pressure-treated with chromated copper arsenate (CCA) wood preservative is commonly used for outdoor construction. Oxides of arsenic, copper, and chromium are bound in the wood by a complex series of chemical reactions, but a small percentage of these compounds are gradually released by leaching and weathering. Recent studies suggest that the release of these...

Rhenium, Molybdenum, Tungsten - Prospects for Production and Industrial Applications

DTIC Science & Technology

1998-06-18

concentrates from unique complex copper -containing porphyry deposit of the Almalyk region. The ore containing over 10 associated valuable constituents is...L.I.Ruzin, M .F.Sherem etyev ............................................... 71 Recovery of rhenium as by-product of treatment of molybdenite and copper ...for processing copper -molybdenum ores from "Erdenet- Ovoo" deposit S.Davaanyam, I.Sh.Sataev, Zh.Baatarkhuu, A.M.Desyatov, M.I.Khersonsky

Conserved active site residues limit inhibition of a copper-containing nitrite reductase by small molecules.

PubMed

Tocheva, Elitza I; Eltis, Lindsay D; Murphy, Michael E P

2008-04-15

The interaction of copper-containing dissimilatory nitrite reductase from Alcaligenes faecalis S-6 ( AfNiR) with each of five small molecules was studied using crystallography and steady-state kinetics. Structural studies revealed that each small molecule interacted with the oxidized catalytic type 2 copper of AfNiR. Three small molecules (formate, acetate and nitrate) mimic the substrate by having at least two oxygen atoms for bidentate coordination to the type 2 copper atom. These three anions bound to the copper ion in the same asymmetric, bidentate manner as nitrite. Consistent with their weak inhibition of the enzyme ( K i >50 mM), the Cu-O distances in these AfNiR-inhibitor complexes were approximately 0.15 A longer than that observed in the AfNiR-nitrite complex. The binding mode of each inhibitor is determined in part by steric interactions with the side chain of active site residue Ile257. Moreover, the side chain of Asp98, a conserved residue that hydrogen bonds to type 2 copper-bound nitrite and nitric oxide, was either disordered or pointed away from the inhibitors. Acetate and formate inhibited AfNiR in a mixed fashion, consistent with the occurrence of second acetate binding site in the AfNiR-acetate complex that occludes access to the type 2 copper. A fourth small molecule, nitrous oxide, bound to the oxidized metal in a side-on fashion reminiscent of nitric oxide to the reduced copper. Nevertheless, nitrous oxide bound at a farther distance from the metal. The fifth small molecule, azide, inhibited the reduction of nitrite by AfNiR most strongly ( K ic = 2.0 +/- 0.1 mM). This ligand bound to the type 2 copper center end-on with a Cu-N c distance of approximately 2 A, and was the only inhibitor to form a hydrogen bond with Asp98. Overall, the data substantiate the roles of Asp98 and Ile257 in discriminating substrate from other small anions.

Condensed, solution and gas phase behaviour of mono- and dinuclear 2,6-diacetylpyridine (dap) hydrazone copper complexes probed by X-ray, mass spectrometry and theoretical calculations.

PubMed

Neto, Brenno A D; Viana, Barbara F L; Rodrigues, Thyago S; Lalli, Priscila M; Eberlin, Marcos N; da Silva, Wender A; de Oliveira, Heibbe C B; Gatto, Claudia C

2013-08-28

We describe the synthesis of novel mononuclear and dinuclear copper complexes and an investigation of their behaviour in solution using mass spectrometry (ESI-MS and ESI-MS/MS) and in the solid state using X-ray crystallography. The complexes were synthesized from two widely used diacetylpryridine (dap) ligands, i.e. 2,6-diacetylpyridinebis(benzoic acid hydrazone) and 2,6-diacetylpyridinebis(2-aminobenzoic acid hydrazone). Theoretical calculations (DFT) were used to predict the complex geometries of these new structures, their equilibrium in solution and energies associated with the transformations.

Selective Production of 2-Methylfuran by Gas-Phase Hydrogenation of Furfural on Copper Incorporated by Complexation in Mesoporous Silica Catalysts.

PubMed

Jiménez-Gómez, Carmen Pilar; Cecilia, Juan A; Moreno-Tost, Ramón; Maireles-Torres, Pedro

2017-04-10

Copper species have been incorporated in mesoporous silica (MS) through complexation with the amine groups of dodecylamine, which was used as a structure-directing agent in the synthesis. A series of Cu/SiO 2 catalysts (xCu-MS) with copper loadings (x) from 2.5 to 20 wt % was synthesized and evaluated in the gas-phase hydrogenation of furfural (FUR). The most suitable catalytic performance in terms of 2-methylfuran yield was obtained with an intermediate copper content (10 wt %). This 10Cu-MS catalyst exhibits a 2-methylfuran yield higher than 95 mol % after 5 h time-on-stream (TOS) at a reaction temperature of 210 °C with a H 2 /FUR molar ratio of 11.5 and a weight hourly space velocity (WHSV) of 1.5 h -1 . After 14 h TOS, this catalyst still showed a yield of 80 mol %. In all cases, carbonaceous deposits on the external surface were the cause of the catalyst deactivation, although sintering of the copper particles was observed for higher copper loadings. This intermediate copper loading (10 wt %) offered a suitable balance between resistance to sintering and tendency to form carbonaceous deposits. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reactivity of lithium n-butyl amidinates towards group 14 metal(II) chlorides providing series of hetero- and homoleptic tetrylenes.

PubMed

Chlupatý, Tomáš; Padělková, Zdeňka; Lyčka, Antonín; Brus, Jiří; Růžička, Aleš

2012-04-28

The new class of homo- and heteroleptic n-butyl-N,N'-disubstituted amidinato group 14 metal(II) complexes were prepared by salt elimination from starting lithium amidinates and metal(II) chlorides both in stoichiometric ratio 2:1 and 1:1, respectively. The target amidinates contain less bulky isopropyl or cyclohexyl as well as a sterically demanding aromatic substituent. Desired 1:1 Pb(II) complexes are not accessible by the described procedure. Ligand transfer from Pb to Sn is taking place if homoleptic Pb(II) compounds are reacted with SnCl(2). Prepared tetrylenes were characterized by (1)H, (13)C, (119)Sn and (207)Pb NMR spectroscopy in C(6)D(6) or THF-d(8). X-Ray diffraction studies of one heteroleptic Ge(II) monomeric where the coordination polyhedron of the three coordinated germanium atoms is a trigonal pyramid, two different dimeric structures of heteroleptic Sn(II) complexes, one amidine hydroiodide byproduct and the oxidation product of the heteroleptic chloro Sn(II) amidinate as a tetranuclear species with two Sn(IV) and two Sn(II) atoms in central Sn(2)O(2) planar ring were performed on appropriate single crystals. The dimer of one of the heteroleptic stannylenes reveals a new type of monomeric units connection, weak Sn-Cl contact and an interaction of the tin atom with delocalized N-C(C)-N system of the amidinato ligand of the second molecule. This journal is © The Royal Society of Chemistry 2012

Modification of Different Zirconium Propoxide Precursors by Diethanolamine. Is There a Shelf Stability Issue for Sol-Gel Applications?

PubMed Central

Spijksma, Gerald I.; Blank, Dave H. A.; Bouwmeester, Henny J. M.; Kessler, Vadim G.

2009-01-01

Modification of different zirconium propoxide precursors with H2dea was investigated by characterization of the isolated modified species. Upon modification of zirconium n-propoxide and [Zr(OnPr)(OiPr)3(iPrOH)]2 with ½ a mol equivalent of H2dea the complexes [Zr2(OnPr)6(OCH2CH2)2NH]2 (1) and [Zr2(OnPr)2(OiPr)4(OCH2CH2)2NH]2 (2) were obtained. However, 1H-NMR studies of these tetranuclear compounds showed that these are not time-stable either in solution or solid form. The effect of this time instability on material properties is demonstrated by light scattering and TEM experiments. Modification of zirconium isopropoxide with either ½ or 1 equivalent mol of H2dea results in formation of the trinuclear complex, Zr{η3μ2-NH(C2H4O)2}3[Zr(OiPr)3]2(iPrOH)2 (3) countering a unique nona-coordinated central zirconium atom. This complex 3 is one of the first modified zirconium propoxide precursors shown to be stable in solution for long periods of time. The particle size and morphology of the products of sol-gel synthesis are strongly dependent on the time factor and eventual heat treatment of the precursor solution. Reproducible sol-gel synthesis requires the use of solution stable precursors. PMID:20087472

A Paramagnetic Copper(III) Complex Containing an Octahedral CuIII S6 Coordination Polyhedron.

PubMed

Krebs, Carsten; Glaser, Thorsten; Bill, Eckhard; Weyhermüller, Thomas; Meyer-Klaucke, Wolfram; Wieghardt, Karl

1999-02-01

Only the second octahedral, paramagnetic copper(III) complex (S=1) has now been synthesized and characterized. Six thiolato bridging ligands in the heterotrinuclear species [LCo III Cu III Co III L](ClO 4 ) 3 ⋅2 Me 2 CO (L=1,4,7-tris(4-tert-butyl-2-sulfidobenzyl)-1,4,7-triazacyclononane) stabilize this rare electron configuration. A section of the structure of the reduced form (Cu II , S=½) is shown. XAS, EXAFS, and EPR spectroscopy prove unambiguously that the one-electron oxidation to the copper(III) is metal- rather than ligand-centered. © 1999 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.

Synthesis and Characterization of Paramagnetic Tungsten Imido Complexes Bearing α-Diimine Ligands.

PubMed

Tanahashi, Hiromasa; Ikeda, Hideaki; Tsurugi, Hayato; Mashima, Kazushi

2016-02-15

Tungsten imido complexes bearing a redox-active ligand, such as N,N'-bis(2,6-diisopropylphenyl)-1,4-diaza-2,3-dimethyl-1,3-butadiene (L1), N,N'-bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene (L2), and 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (L3), were prepared by salt-free reduction of W(═NC6H3-2,6-(i)Pr2)Cl4 (1) using 1-methyl-3,6-bis(trimethylsilyl)-1,4-cyclohexadiene (MBTCD) followed by addition of the corresponding redox-active ligands. In the initial stage, reaction of W(═NC6H3-2,6-(i)Pr2)Cl4 with MBTCD afforded a tetranuclear W(V) imido cluster, [W(═NC6H3-2,6-(i)Pr2)Cl3]4 (2), which served as a unique precursor for introducing redox-active ligands to the tungsten center to give the corresponding mononuclear complexes with a general formula of W(═NC6H3-2,6-(i)Pr2)Cl3(L) (3, L = L1; 4, L = L2; and 6, L = L3). X-ray analyses of complexes 3 and 6 revealed a neutral coordination mode of L1 and L3 to the tungsten in solid state, while the electron paramagnetic resonance (EPR) spectra of 3 and 4 clarified that a radical was predominantly located on the tungsten center supported by neutral L1 or L2, and the EPR spectra of complex 6 indicated that a radical was delocalized over both the tungsten center and the monoanionic redox-active ligand L3.

Cu(II) potentiation of Alzheimer Abeta1-40 cytotoxicity and transition on its secondary structure.

PubMed

Dai, Xue-Ling; Sun, Ya-Xuan; Jiang, Zhao-Feng

2006-11-01

Mounting evidence has shown that dyshomeostasis of the redox-active biometals such as Cu and Fe can lead to oxidative stress, which plays a key role in the neuropathology of Alzheimer' disease (AD). Here we demonstrate that with the formation of Cu(II).beta1-40 complexes, copper markedly potentiates the neurotoxicity exhibited by beta-amyloid peptide (Ab). A greater amount of hydrogen peroxide was released when Cu(II).beta1-40 complexes was added to the xanthine oxidase/xanthine system detected by potassium iodide spectrophotometry. Copper bound to Abeta1-40 was observed by electron paramagnetic resonance (EPR) spectroscopy. Circular dichroism (CD) studies indicated that copper chelation could cause a structural transition of Abeta. The addition of copper to Ab introduced an increase on beta-sheet as well as alpha-helix, which may be responsible for the aggregation of Abeta. We hypothesized that Abeta aggregation induced by copper may be responsible for local injury in AD. The interaction between Cu(2+) and Ab also provides a possible mechanism for the enrichment of metal ions in amyloid plaques in the AD brain.

The importance of extracellular speciation and corrosion of copper nanoparticles on lung cell membrane integrity.

PubMed

Hedberg, Jonas; Karlsson, Hanna L; Hedberg, Yolanda; Blomberg, Eva; Odnevall Wallinder, Inger

2016-05-01

Copper nanoparticles (Cu NPs) are increasingly used in various biologically relevant applications and products, e.g., due to their antimicrobial and catalytic properties. This inevitably demands for an improved understanding on their interactions and potential toxic effects on humans. The aim of this study was to investigate the corrosion of copper nanoparticles in various biological media and to elucidate the speciation of released copper in solution. Furthermore, reactive oxygen species (ROS) generation and lung cell (A549 type II) membrane damage induced by Cu NPs in the various media were studied. The used biological media of different complexity are of relevance for nanotoxicological studies: Dulbecco's modified eagle medium (DMEM), DMEM(+) (includes fetal bovine serum), phosphate buffered saline (PBS), and PBS+histidine. The results show that both copper release and corrosion are enhanced in DMEM(+), DMEM, and PBS+histidine compared with PBS alone. Speciation results show that essentially no free copper ions are present in the released fraction of Cu NPs in neither DMEM(+), DMEM nor histidine, while labile Cu complexes form in PBS. The Cu NPs were substantially more membrane reactive in PBS compared to the other media and the NPs caused larger effects compared to the same mass of Cu ions. Similarly, the Cu NPs caused much more ROS generation compared to the released fraction only. Taken together, the results suggest that membrane damage and ROS formation are stronger induced by Cu NPs and by free or labile Cu ions/complexes compared with Cu bound to biomolecules. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Inhibition of copper-mediated aggregation of human γD-crystallin by Schiff bases.

PubMed

Chauhan, Priyanka; Muralidharan, Sai Brinda; Velappan, Anand Babu; Datta, Dhrubajyoti; Pratihar, Sanjay; Debnath, Joy; Ghosh, Kalyan Sundar

2017-06-01

Protein aggregation, due to the imbalance in the concentration of Cu 2+ and Zn 2+ ions is found to be allied with various physiological disorders. Copper is known to promote the oxidative damage of β/γ-crystallins in aged eye lens and causes their aggregation leading to cataract. Therefore, synthesis of a small-molecule 'chelator' for Cu 2+ with complementary antioxidant effect will find potential applications against aggregation of β/γ-crystallins. In this paper, we have reported the synthesis of different Schiff bases and studied their Cu 2+ complexation ability (using UV-Vis, FT-IR and ESI-MS) and antioxidant activity. Further based on their copper complexation efficiency, Schiff bases were used to inhibit Cu 2+ -mediated aggregation of recombinant human γD-crystallin (HGD) and β/γ-crystallins (isolated from cataractous human eye lens). Among these synthesized molecules, compound 8 at a concentration of 100 μM had shown ~95% inhibition of copper (100 μM)-induced aggregation. Compound 8 also showed a positive cooperative effect at a concentration of 5-15 μM on the inhibitory activity of human αA-crystallin (HAA) during Cu 2+ -induced aggregation of HGD. It eventually inhibited the aggregation process by additional ~20%. However, ~50% inhibition of copper-mediated aggregation of β/γ-crystallins (isolated from cataractous human eye lens) was recorded by compound 8 (100 μM). Although the reductive aminated products of the imines showed better antioxidant activity due to their lower copper complexing ability, they were found to be non-effective against Cu 2+ -mediated aggregation of HGD.

Fetal and neonatal iron deficiency but not copper deficiency increases vascular complexity in the developing rat brain

PubMed Central

Bastian, Thomas W.; Santarriaga, Stephanie; Nguyen, Thu An; Prohaska, Joseph R.; Georgieff, Michael K.; Anderson, Grant W.

2015-01-01

Objectives Anemia caused by nutritional deficiencies, such as iron and copper deficiencies, is a global health problem. Iron and copper deficiencies have their most profound effect on the developing fetus/infant, leading to brain development deficits and poor cognitive outcomes. Tissue iron depletion or chronic anemia can induce cellular hypoxic signaling. In mice, chronic hypoxia induces a compensatory increase in brain blood vessel outgrowth. We hypothesized that developmental anemia, due to iron or copper deficiencies, induces angiogenesis/vasculogenesis in the neonatal brain. Methods To test our hypothesis, three independent experiments were performed where pregnant rats were fed iron- or copper-deficient diets from gestational day 2 through mid-lactation. Effects on the neonatal brain vasculature were determined using qPCR to assess mRNA levels of angiogenesis/vasculogenesis-associated genes and GLUT1 immunohistochemistry (IHC) to assess brain blood vessel density and complexity. Results Iron deficiency, but not copper deficiency, increased mRNA expression of brain endothelial cell- and angiogenesis/vasculogenesis-associated genes (i.e. Glut1, Vwf, Vegfa, Ang2, Cxcl12, and Flk1) in the neonatal brain, suggesting increased cerebrovascular density. Iron deficiency also increased hippocampal and cerebral cortical blood vessel branching by 62% and 78%, respectively. Discussion This study demonstrates increased blood vessel complexity in the neonatal iron-deficient brain, which is likely due to elevated angiogenic/vasculogenic signaling. At least initially, this is probably an adaptive response to maintain metabolic substrate homeostasis in the developing iron-deficient brain. However, this may also contribute to long-term neurodevelopmental deficits. PMID:26177275

Synergistic extraction and spectrophotometric determination of copper(II) using 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol: Analysis of alloys, pharmaceuticals and biological samples

NASA Astrophysics Data System (ADS)

Kamble, Ganesh S.; Kolekar, Sanjay S.; Anuse, Mansing A.

2011-05-01

A simple and selective spectrophotometric method was developed for the determination of copper(II) with 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2',4'-dinitro APTPT] as a chromogenic reagent. The procedure was based on the synergistic extraction of copper(II) with 2',4'-dinitro APTPT in the presence of 0.5 mol L -1 pyridine to give green colored ternary complex of a molar ratio 1:2:2 (M:L:Py) in the pH range 8.7-10.5. It exhibits a maximum absorption of colored complex at 445 nm and 645 nm in chloroform against the reagent blank. Beer's law was followed in the concentration range 10-80 μg mL -1 of copper(II) and optimum range of 20-70 μg mL -1 the metal as evaluated from Ringbom's plot. The molar absorptivity and Sandell's sensitivity of copper(II)-2',4'-dinitro APTPT-pyridine complex in chloroform are 0.87 × 10 3 L mol -1 cm -1 and 0.072 μg cm -2, respectively. The interfering effects of various cations and anions were also studied, and use of suitable masking agents enhances the selectivity of the method. The proposed method is rapid, reproducible and successfully applied for the determination of copper(II) in binary and synthetic mixtures, alloys, pharmaceutical formulations, environmental and fertilizer samples. Comparison of the results with those obtained using an atomic absorption spectrophotometer also tested the validity of the method.

CELLULAR MULTITASKING: THE DUAL ROLE OF HUMAN CU-ATPASES IN COFACTOR DELIVERY AND INTRACELLULAR COPPER BALANCE

PubMed Central

Lutsenko, Svetlana; Gupta, Arnab; Burkhead, Jason L.; Zuzel, Vesna

2008-01-01

Summary The human copper-transporting ATPases (Cu-ATPases) are essential for dietary copper uptake, normal development and function of the CNS, and regulation of copper homeostasis in the body. In a cell, Cu-ATPases maintain the intracellular concentration of copper by transporting copper into intracellular exocytic vesicles. In addition, these P-type ATPases mediate delivery of copper to copper-dependent enzymes in the secretory pathway and in specialized cell compartments such as secretory granules or melanosomes. The multiple functions of human Cu-ATPase necessitate complex regulation of these transporters that is mediated through the presence of regulatory domains in their structure, posttranslational modification and intracellular trafficking, as well as interactions with the copper chaperone Atox1 and other regulatory molecules. In this review, we summarize the current information on the function and regulatory mechanisms acting on human Cu-ATPases ATP7A and ATP7B. Brief comparison with the Cu-ATPase orthologues from other species is included. PMID:18534184

A Polyoxoniobate-Polyoxovanadate Double-Anion Catalyst for Simultaneous Oxidative and Hydrolytic Decontamination of Chemical Warfare Agent Simulants.

PubMed

Dong, Jing; Hu, Jufang; Chi, Yingnan; Lin, Zhengguo; Zou, Bo; Yang, Song; Hill, Craig L; Hu, Changwen

2017-04-10

A novel double-anion complex, H 13 [(CH 3 ) 4 N] 12 [PNb 12 O 40 (V V O) 2 ⋅(V IV 4 O 12 ) 2 ]⋅22 H 2 O (1), based on bicapped polyoxoniobate and tetranuclear polyoxovanadate was synthesized, characterized by routine techniques and used in the catalytic decontamination of chemical warfare agents. Under mild conditions, 1 catalyzes both hydrolysis of the nerve agent simulant, diethyl cyanophosphonate (DECP) and selective oxidation of the sulfur mustard simulant, 2-chloroethyl ethyl sulfide (CEES). In the oxidative decontamination system 100 % CEES was transformed selectively to nontoxic 2-chloroethyl ethyl sulfoxide and vinyl ethyl sulfoxide using nearly stoichiometric 3 % aqueous H 2 O 2 with a turnover frequency (TOF) of 16 000 h -1 . Importantly, the catalytic activity is maintained even after ten recycles and CEES is completely decontaminated in 3 mins without formation of the highly toxic sulfone by-product. A three-step oxidative mechanism is proposed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Activation of the MAPK11/12/13/14 (p38 MAPK) pathway regulates the transcription of autophagy genes in response to oxidative stress induced by a novel copper complex in HeLa cells.

PubMed

Zhong, Wu; Zhu, Haichuan; Sheng, Fugeng; Tian, Yonglu; Zhou, Jun; Chen, Yingyu; Li, Song; Lin, Jian

2014-07-01

Transition metal copper (Cu) can exist in oxidized or reduced states in cells, leading to cytotoxicity in cancer cells through oxidative stress. Recently, copper complexes are emerging as a new class of anticancer compounds. Here, we report that a novel anticancer copper complex (HYF127c/Cu) induces oxidative stress-dependent cell death in cancer cells. Further, transcriptional analysis revealed that oxidative stress elicits broad transcriptional changes of genes, in which autophagy-related genes are significantly changed in HYF127c/Cu-treated cells. Consistently, autophagy was induced in HYF127c/Cu-treated cells and inhibitors of autophagy promoted cell death induced by HYF127c/Cu. Further analysis identified that the MAPK11/12/13/14 (formerly known as p38 MAPK) pathway was also activated in HYF127c/Cu-treated cells. Meanwhile, the MAPK11/12/13/14 inhibitor SB203580 downregulated autophagy by inhibiting the transcription of the autophagy genes MAP1LC3B, BAG3, and HSPA1A, and promoted HYF127c/Cu-induced cell death. These data suggest that copper-induced oxidative stress will induce protective autophagy through transcriptional regulation of autophagy genes by activation of the MAPK11/12/13/14 pathway in HeLa cells.

Development of Composite Spectrophotometric Procedures for the Analysis of Low-Alloy Steels and of Aluminum and Its Alloys

DTIC Science & Technology

1952-11-01

COPPER lb Although copper can be determined by measurement of the blue cupric ammonia complex, the reaction is not very sensitive and is subject to...alkaline solution of the sample con- taining tartrate , provided a means of separation of copper by extraction of WADO TR 52-246 1 the copper bensoinoximate...potassium tartrate ), and sodium hydroxide solution added to ad- just the pH within the range ll3 to 12-3. After adding alpha-benzoinoxime the mixture was

Synthesis, electrochemical, structural, spectroscopic and biological activities of mixed ligand copper (II) complexes with 2-{[(Z)-(5-bromo-2-hydroxyphenyl)methylidene]amino}benzoic acid and nitrogenous bases

NASA Astrophysics Data System (ADS)

Choudhary, Mukesh; Patel, R. N.; Rawat, S. P.

2014-02-01

Three new copper (II) complexes viz. [Cu(L1)(bipy)]ṡ2H2O 1, [Cu(L1)(dmp)]ṡCH3CN 2, [Cu(L1)(phen)] 3 where L1H2 = 2-{[(Z)-(5-bromo-2-hydroxyphenyl)methylidene]amino}benzoic acid, bipy = 2,2‧-bipyridine; dmp = 2,9-dimethyl 1,10-phenanthroline, phen = 1,10-phenanthroline have been synthesized and characterized by physic-chemical and spectroscopic methods. The solid-state structures of 1 and 2 were determined by single crystal X-ray crystallography, which revealed distorted square pyramidal geometry. In solid-state structure, 1 is self-assembled via intermolecular π…π stacking and the distances between centroids of aromatic ring is 3.525 Å. L1H2 is a diprotic tridentate Schiff base ligand having ONO donor site. Infrared spectra, ligand field spectra and magnetic susceptibility measurements agree with the observed crystal structures. The EPR spectra of these complexes in frozen DMSO solutions showed a single at g ca. 2. The trend in g-value (g|| > g⊥ > 2.0023) suggests that the unpaired electron on copper (II) has d character. Copper (II) complexes 1-3 yielded an irreversible couple corresponding to the Cu (II)/Cu (I) redox process. Superoxide dismutase activity of all these complexes has been revealed to catalyze the dismutation of superoxide (O2-) and IC50 values were evaluated and discussed. Antimicrobial and antifungal activities of these complexes were also investigated.

Synthesis, characterization, and antimicrobial activity of silver(I) and copper(II) complexes of phosphate derivatives of pyridine and benzimidazole.

PubMed

Kalinowska-Lis, Urszula; Szewczyk, Eligia M; Chęcińska, Lilianna; Wojciechowski, Jakub M; Wolf, Wojciech M; Ochocki, Justyn

2014-01-01

Two silver(I) complexes--[Ag(4-pmOpe)]NO₃}(n) and [Ag(2-bimOpe)₂]NO₃--and three copper(II) complexes--[Cu₄Cl₆O(2-bimOpe)₄], [CuCl₂(4-pmOpe)₂], and [CuCl₂(2-bis(pm)Ope]--were synthesized by reaction of silver(I) nitrate or copper(II) chloride with phosphate derivatives of pyridine and benzimidazole, namely diethyl (pyridin-4-ylmethyl)phosphate (4-pmOpe), 1H-benzimidazol-2-ylmethyl diethyl phosphate (2-bimOpe), and ethyl bis(pyridin-2-ylmethyl)phosphate (2-bis(pm)Ope). These compounds were characterized by ¹H, ¹³C, and ³¹P NMR as well as IR spectroscopy, elemental analysis, and ESIMS spectrometry. Additionally, molecular and crystal structures of {[Ag(4-pmOpe)]NO₃}n and [Cu₄Cl₆O(2-bimOpe)₄] were determined by single-crystal X-ray diffraction analysis. The antimicrobial profiles of synthesized complexes and free ligands against test organisms from the ATCC and clinical sources were determined. Silver(I) complexes showed good antimicrobial activities against Candida albicans strains (MIC values of ∼19 μM). [Ag(2-bimOpe)₂]NO₃ was particularly active against Pseudomonas aeruginosa and methicillin-resistant Staphylococcus epidermidis, with MIC values of ∼5 and ∼10 μM, respectively. Neither copper(II) complexes nor the free ligands inhibited the growth of test organisms at concentrations below 500 μg mL⁻¹. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A spin-frustrated trinuclear copper complex based on triaminoguanidine with an energetically well-separated degenerate ground state.

PubMed

Spielberg, Eike T; Gilb, Aksana; Plaul, Daniel; Geibig, Daniel; Hornig, David; Schuch, Dirk; Buchholz, Axel; Ardavan, Arzhang; Plass, Winfried

2015-04-06

We present the synthesis and crystal structure of the trinuclear copper complex [Cu3(saltag)(bpy)3]ClO4·3DMF [H5saltag = tris(2-hydroxybenzylidene)triaminoguanidine; bpy = 2,2'-bipyridine]. The complex crystallizes in the trigonal space group R3̅, with all copper ions being crystallographically equivalent. Analysis of the temperature dependence of the magnetic susceptibility shows that the triaminoguanidine ligand mediates very strong antiferromagnetic interactions (JCuCu = -324 cm(-1)). Detailed analysis of the magnetic susceptibility and magnetization data as well as X-band electron spin resonance spectra, all recorded on both powdered samples and single crystals, show indications of neither antisymmetric exchange nor symmetry lowering, thus indicating only a very small splitting of the degenerate S = (1)/2 ground state. These findings are corroborated by density functional theory calculations, which explain both the strong isotropic and negligible antisymmetric exchange interactions.

Synthesis, characterization and catalytic oxidation properties of multi-wall carbon nanotubes with a covalently attached copper(II) salen complex

NASA Astrophysics Data System (ADS)

Salavati-Niasari, Masoud; Bazarganipour, Mehdi

2009-06-01

Hydroxyl functionalized copper(II) Schiff-base, N,N'-bis(4-hydroxysalicylidene)-ethylene-1,2-diaminecopper(II), [Cu((OH) 2-salen)], has been covalently anchored on modified MWCNTs. The new modified MWCNTs ([Cu((OH) 2-salen)]-MWCNTs) have been characterized by TEM, thermal analysis, XRD, XPS, UV-vis, DRS, FT-IR spectroscopy and elemental analysis. The modified copper(II) MWCNTs solid was used to affect the catalytic oxidation of ethylbenzene with tert-butylhydroperoxide as the oxidant at 333 K. The system is truly heterogeneous (no leaching observed) and reusable (no decrease in activity) in three consecutive runs. Acetophenone was the major product though small amounts of o- and p-hydroxyacetophenones were also formed revealing that C-H bond activation takes place both at benzylic and aromatic ring carbon atoms. Ring hydroxylation was more over the "neat" complexes than over the encapsulated complexes.

c-Type Cytochrome Assembly Is a Key Target of Copper Toxicity within the Bacterial Periplasm

PubMed Central

Durand, Anne; Azzouzi, Asma; Bourbon, Marie-Line; Steunou, Anne-Soisig; Liotenberg, Sylviane; Maeshima, Akinori; Astier, Chantal; Argentini, Manuela; Saito, Shingo

2015-01-01

ABSTRACT In the absence of a tight control of copper entrance into cells, bacteria have evolved different systems to control copper concentration within the cytoplasm and the periplasm. Central to these systems, the Cu+ ATPase CopA plays a major role in copper tolerance and translocates copper from the cytoplasm to the periplasm. The fate of copper in the periplasm varies among species. Copper can be sequestered, oxidized, or released outside the cells. Here we describe the identification of CopI, a periplasmic protein present in many proteobacteria, and show its requirement for copper tolerance in Rubrivivax gelatinosus. The ΔcopI mutant is more susceptible to copper than the Cu+ ATPase copA mutant. CopI is induced by copper, localized in the periplasm and could bind copper. Interestingly, copper affects cytochrome c membrane complexes (cbb3 oxidase and photosystem) in both ΔcopI and copA-null mutants, but the causes are different. In the copA mutant, heme and chlorophyll synthesis are affected, whereas in ΔcopI mutant, the decrease is a consequence of impaired cytochrome c assembly. This impact on c-type cytochromes would contribute also to the copper toxicity in the periplasm of the wild-type cells when they are exposed to high copper concentrations. PMID:26396241

X-ray absorption spectral studies of copper (II) mixed ligand complexes

NASA Astrophysics Data System (ADS)

Soni, B.; Dar, Davood Ah; Shrivastava, B. D.; Prasad, J.; Srivastava, K.

2014-09-01

X-ray absorption spectra at the K-edge of copper have been studied in two copper mixed ligand complexes, one having tetramethyethylenediamine (tmen) and the other having tetraethyethylenediamine (teen) as one of the ligands. The spectra have been recorded at BL-8 dispersive extended X-ray absorption fine structure (EXAFS) beamline at the 2.5 GeV INDUS- 2 synchrotron, RRCAT, Indore, India. The data obtained has been processed using the data analysis program Athena. The energy of the K-absorption edge, chemical shift, edge-width and shift of the principal absorption maximum in the complexes have been determined and discussed. The values of these parameters have been found to be approximately the same in both the complexes indicating that the two complexes possess similar chemical environment around the copper metal atom. The chemical shift has been utilized to estimate effective nuclear charge on the absorbing atom. The normalized EXAFS spectra have been Fourier transformed. The position of the first peak in the Fourier transform gives the value of first shell bond length, which is shorter than the actual bond length because of energy dependence of the phase factors in the sine function of the EXAFS equation. This distance is thus the phase- uncorrected bond length. Bond length has also been determined by Levy's, Lytle's and Lytle, Sayers and Stern's (LSS) methods. The results obtained from LSS and the Fourier transformation methods are comparable with each other, since both are phase uncorrected bond lengths.

Optical properties of trinuclear metal chalcogenolate complexes - room temperature NIR fluorescence in [Cu2Ti(SPh)6(PPh3)2].

PubMed

Kühn, Michael; Lebedkin, Sergei; Weigend, Florian; Eichhöfer, Andreas

2017-01-31

The optical properties of four isostructural trinuclear chalcogenolato bridged metal complexes [Cu 2 Sn(SPh) 6 (PPh 3 ) 2 ], [Cu 2 Sn(SePh) 6 (PPh 3 ) 2 ], [Ag 2 Sn(SPh) 6 (PPh 3 ) 2 ] and [Cu 2 Ti(SPh) 6 (PPh 3 ) 2 ] have been investigated by absorption and photoluminescence spectroscopy and time-dependent density functional theory (TDDFT) calculations. All copper-tin compounds demonstrate near-infrared (NIR) phosphorescence at ∼900-1100 nm in the solid state at low temperature, which is nearly absent at ambient temperature. Stokes shifts of these emissions are found to be unusually large with values of about 1.5 eV. The copper-titanium complex [Cu 2 Ti(SPh) 6 (PPh 3 ) 2 ] also shows luminescence in the NIR at 1090 nm but with a much faster decay (τ ∼ 10 ns at 150 K) and a much smaller Stokes shift (ca. 0.3 eV). Even at 295 K this fluorescence is found to comprise a quantum yield as high as 9.5%. The experimental electronic absorption spectra well correspond to the spectra simulated from the calculated singlet transitions. In line with the large Stokes shifts of the emission spectra the calculations reveal for the copper-tin complexes strong structural relaxation of the excited triplet states whereas those effects are found to be much smaller in the case of the copper-titanium complex.

Copper(II) Thiosemicarbazone Complexes and Their Proligands upon UVA Irradiation: An EPR and Spectrophotometric Steady-State Study.

PubMed

Hricovíni, Michal; Mazúr, Milan; Sîrbu, Angela; Palamarciuc, Oleg; Arion, Vladimir B; Brezová, Vlasta

2018-03-21

X- and Q-band electron paramagnetic resonance (EPR) spectroscopy was used to characterize polycrystalline Cu(II) complexes that contained sodium 5-sulfonate salicylaldehyde thiosemicarbazones possessing a hydrogen, methyl, ethyl, or phenyl substituent at the terminal nitrogen. The ability of thiosemicarbazone proligands to generate superoxide radical anions and hydroxyl radicals upon their exposure to UVA irradiation in aerated aqueous solutions was evidenced by the EPR spin trapping technique. The UVA irradiation of proligands in neutral or alkaline solutions and dimethylsulfoxide (DMSO) caused a significant decrease in the absorption bands of aldimine and phenolic chromophores. Mixing of proligand solutions with the equimolar amount of copper(II) ions resulted in the formation of 1:1 Cu(II)-to-ligand complex, with the EPR and UV-Vis spectra fully compatible with those obtained for the dissolved Cu(II) thiosemicarbazone complexes. The formation of the complexes fully inhibited the photoinduced generation of reactive oxygen species, and only subtle changes were found in the electronic absorption spectra of the complexes in aqueous and DMSO solutions upon UVA steady-state irradiation. The dark redox activity of copper(II) complexes and proligand/Cu(II) aqueous solutions towards hydrogen peroxide which resulted in the generation of hydroxyl radicals, was confirmed by spin trapping experiments.

Synthesis, X-ray crystal structures, and phosphate ester cleavage properties of bis(2-pyridylmethyl)amine copper(II) complexes with guanidinium pendant groups.

PubMed

Belousoff, Matthew J; Tjioe, Linda; Graham, Bim; Spiccia, Leone

2008-10-06

Three new derivatives of bis(2-pyridylmethyl)amine (DPA) featuring ethylguanidinium (L (1)), propylguanidinium (L (2)), or butylguanidinium (L (3)) pendant groups have been prepared by the reaction of N, N- bis(2-pyridylmethyl)alkane-alpha,omega-diamines with 1 H-pyrazole-1-carboxamidine hydrochloride. The corresponding mononuclear copper(II) complexes were prepared by reacting the ligands with copper(II) nitrate and were isolated as [Cu(LH (+))(OH 2)](ClO 4) 3. xNaClO 4. yH 2O ( C1: L = L (1), x = 2, y = 3; C2: L = L (2), x = 2, y = 4; C3: L = L (3), x = 1, y = 0) following cation exchange purification. Recrystallization yielded crystals of composition [Cu(LH (+))(X)](ClO 4) 3.X ( C1': L = L (1), X = MeOH; C2': L = L (2), X = H 2O; C3': L = L (3), X = H 2O), which were suitable for X-ray crystallography. The crystal structures of C1', C2', and C3' indicate that the DPA moieties of the ligands coordinate to the copper(II) centers in a meridional fashion, with a water or methanol molecule occupying the fourth basal position. Weakly bound perchlorate anions located in the axial positions complete the distorted octahedral coordination spheres. The noncoordinating, monoprotonated guanidinium groups project away from the Cu(II)-DPA units and are involved in extensive charge-assisted hydrogen-bonding interactions with cocrystallized water/methanol molecules and perchlorate anions within the crystal lattices. The copper(II) complexes were tested for their ability to promote the cleavage of two model phosphodiesters, bis( p-nitrophenyl)phosphate (BNPP) and uridine-3'- p-nitrophenylphosphate (UpNP), as well as supercoiled plasmid DNA (pBR 322). While the presence of the guanidine pendants was found to be detrimental to BNPP cleavage efficiency, the functionalized complexes were found to cleave plasmid DNA and, in some cases, the model ribose phosphate diester, UpNP, at a faster rate than the parent copper(II) complex of DPA.

Copper(I)- and copper(0)-promoted homocoupling and homocoupling-hydrodehalogenation reactions of dihalogenoclathrochelate precursors for C-C conjugated iron(II) bis-cage complexes.

PubMed

Varzatskii, Oleg A; Shul'ga, Sergey V; Belov, Alexander S; Novikov, Valentin V; Dolganov, Alexander V; Vologzhanina, Anna V; Voloshin, Yan Z

2014-12-28

Iron(II) dibromo- and diiodoclathrochelates undergo copper(I)-promoted reductive homocoupling in HMPA at 70-80 °C leading to C-C conjugated dibromo- and diiodo-bis-clathrochelates in high yields. Under the same conditions, their dichloroclathrochelate analog does not undergo the same homocoupling reaction, so the target dichloro-bis-cage product was obtained in high yield via dimerization of its heterodihalogenide iodochloromonomacrobicyclic precursor. The use of NMP as a solvent at 120-140 °C gave the mixture of bis-clathrochelates resulting from a tandem homocoupling-hydrodehalogenation reaction: the initial acetonitrile copper(I) solvato-complex at a high temperature underwent re-solvatation and disproportionation leading to Cu(II) ions and nano-copper, which promoted the hydrodehalogenation process even at room temperature. The most probable pathway of this reaction in situ includes hydrodehalogenation of the already formed dihalogeno-bis-clathrochelate via the formation of reduced anion radical intermediates. As a result, chemical transformations of the iron(II) dihalogenoclathrochelates in the presence of an acetonitrile copper(I) solvato-complex were found to depend both on the nature of halogen atoms in their ribbed chelate fragments and on reaction conditions (i.e. solvent and temperature). The C-C conjugated iron(II) dihalogeno-bis-clathrochelates easily undergo nucleophilic substitution with various N,S-nucleophiles giving ribbed-functionalized bis-cage species. These iron(II) complexes were characterized by elemental analysis, MALDI-TOF mass spectrometry, IR, UV-Vis, (1)H and (13)C NMR spectroscopy, and by X-ray diffraction; their electrochemical properties were studied by cyclic voltammetry. The isomeric shift values in (57)Fe Mössbauer spectra of such cage compounds allowed identifying them as low-spin iron(II) complexes, while those of the quadrupole splitting are the evidence for a significant TP distortion of their FeN6-coordination polyhedra. As follows from CV data, the C-C conjugated iron(II) bis-clathrochelates undergo stepwise electrochemical reduction and oxidation giving mixed-valence Fe(II)Fe(I) and Fe(II)Fe(III) bis-cage intermediates.

Protection of Metal Artifacts with the Formation of Metal–Oxalates Complexes by Beauveria bassiana

PubMed Central

Joseph, Edith; Cario, Sylvie; Simon, Anaële; Wörle, Marie; Mazzeo, Rocco; Junier, Pilar; Job, Daniel

2012-01-01

Several fungi present high tolerance to toxic metals and some are able to transform metals into metal–oxalate complexes. In this study, the ability of Beauveria bassiana to produce copper oxalates was evaluated. Growth performance was tested on various copper-containing media. B. bassiana proved highly resistant to copper, tolerating concentrations of up to 20 g L−1, and precipitating copper oxalates on all media tested. Chromatographic analyses showed that this species produced oxalic acid as sole metal chelator. The production of metal–oxalates can be used in the restoration and conservation of archeological and modern metal artifacts. The production of copper oxalates was confirmed directly using metallic pieces (both archeological and modern). The conversion of corrosion products into copper oxalates was demonstrated as well. In order to assess whether the capability of B. bassiana to produce metal–oxalates could be applied to other metals, iron and silver were tested as well. Iron appears to be directly sequestered in the wall of the fungal hyphae forming oxalates. However, the formation of a homogeneous layer on the object is not yet optimal. On silver, a co-precipitation of copper and silver oxalates occurred. As this greenish patina would not be acceptable on silver objects, silver reduction was explored as a tarnishing remediation. First experiments showed the transformation of silver nitrate into nanoparticles of elemental silver by an unknown extracellular mechanism. The production of copper oxalates is immediately applicable for the conservation of copper-based artifacts. For iron and silver this is not yet the case. However, the vast ability of B. bassiana to transform toxic metals using different immobilization mechanisms seems to offer considerable possibilities for industrial applications, such as the bioremediation of contaminated soils or the green synthesis of chemicals. PMID:22291684

Influence of indigenous and added iron on copper extraction from soil.

PubMed

Di Palma, Luca

2009-10-15

Experimental tests of copper leaching from a low permeability soil are presented and discussed. The objective of the experiments was to investigate the influence of indigenous and added iron in the soil towards copper mobilization. Metals' leaching was performed by flushing (column tests) or washing (batch tests) the soil with an aqueous solution of ethylenediaminetetraacetic acid, EDTA. An excess of EDTA was used in flushing tests (up to a EDTA:Cu molar ratio of about 26.2:1), while, in washing tests, the investigated EDTA vs. copper molar ratios were in the range between 1 (equimolar tests) and 8. Copper extraction yield in flushing tests (up to about 85%) was found to depend upon contact time between the soil and the leaching solution and the characteristics of the conditioning solution. The saturation of the soil with a NaNO(3) solution before the treatment, favoured the flushing process reducing the time of percolation, but resulted in a lower metal extraction during the following percolation of EDTA. The indigenous iron was competitive with copper to form EDTA complexes only when it was present in the organic and oxides-hydroxides fractions. Artificial iron addition to the soil resulted in an increase of both the exchangeable iron and the iron bonded to the organic fraction of the soil, thus increasing the overall amount of iron available to extraction. In both batch and continuous tests, the mechanism of copper extraction was found to involve the former dissolution of metal salts, that lead to an initial high concentration of both copper and selected competitive cations (essentially Ca(2+)), and the following EDTA exchange reaction between calcium and copper complexes. The initial metal salts dissolution was found to be pH-dependant.

A copper(I) dye-sensitised TiO2-based system for efficient light harvesting and photoconversion of CO2 into hydrocarbon fuel.

PubMed

Yuan, Yong-Jun; Yu, Zhen-Tao; Zhang, Ji-Yuan; Zou, Zhi-Gang

2012-08-28

A new copper(I) complex with the ability to bind to TiO(2) was synthesised and successfully employed as a solar cell sensitizer. Furthermore, we demonstrated that the copper(I) dye-sensitised TiO(2)-based photocatalyst exhibits impressive effectiveness for the selective photoreduction of CO(2) to CH(4) under visible light.

Copper complexes of anionic nitrogen ligands in the amidation and imidation of aryl halides.

PubMed

Tye, Jesse W; Weng, Zhiqiang; Johns, Adam M; Incarvito, Christopher D; Hartwig, John F

2008-07-30

Copper(I) imidate and amidate complexes of chelating N,N-donor ligands, which are proposed intermediates in copper-catalyzed amidations of aryl halides, have been synthesized and characterized by X-ray diffraction and detailed solution-phase methods. In some cases, the complexes adopt neutral, three-coordinate trigonal planar structures in the solid state, but in other cases they adopt an ionic form consisting of an L 2Cu (+) cation and a CuX 2 (-) anion. A tetraalkylammonium salt of the CuX 2 (-) anion in which X = phthalimidate was also isolated. Conductivity measurements and (1)H NMR spectra of mixtures of two complexes all indicate that the complexes exist predominantly in the ionic form in DMSO and DMF solutions. One complex was sufficiently soluble for conductance measurements in less polar solvents and was shown to adopt some degree of the ionic form in THF and predominantly the neutral form in benzene. The complexes containing dative nitrogen ligands reacted with iodoarenes and bromoarenes to form products from C-N coupling, but the ammonium salt of [Cu(phth) 2] (-) did not. Similar selectivities for stoichiometric and catalytic reactions with two different iodoarenes and faster rates for the stoichiometric reactions implied that the isolated amidate and imidate complexes are intermediates in the reactions of amides and imides with haloarenes catalyzed by copper complexes containing dative N,N ligands. These amidates and imidates reacted much more slowly with chloroarenes, including chloroarenes that possess more favorable reduction potentials than some bromoarenes and that are known to undergo fast dissociation of chloride from the chloroarene radical anion. The reaction of o-(allyloxy)iodobenzene with [(phen) 2Cu][Cu(pyrr) 2] results in formation of the C-N coupled product in high yield and no detectable amount of the 3-methyl-2,3-dihydrobenzofuran or 3-methylene-2,3-dihydrobenzofuran products that would be expected from a reaction that generated free radicals. These data and computed reaction barriers argue against mechanisms in which the haloarene reacts with a two-coordinate anionic copper species and mechanisms that start with electron transfer to generate a free iodoarene radical anion. Instead, these data are more consistent with mechanisms involving cleavage of the carbon-halogen bond within the coordination sphere of the metal.

Theoretical study of hydrated copper(II) interactions with guanine: a computational density functional theory study.

PubMed

Pavelka, Matej; Shukla, Manoj K; Leszczynski, Jerzy; Burda, Jaroslav V

2008-01-17

Optimization of the hydrated Cu(II)(N7-guanine) structures revealed a number of minima on the potential energy surface. For selected structures, energy decompositions together with the determination of electronic properties (partial charges and electron spin densities) were performed. In the complexes of guanine with the bare copper cation and that with the monoaqua ligated cation, an electron transfer from guanine to Cu(II) was observed, resulting in a Cu(I)-guanine(+) type of complex. Conformers with two aqua ligands are borderline systems characterized by a Cu partial charge of +0.7e and a similar value of the spin density (0.6e) localized on guanine. When tetracoordination of copper was achieved, only then the prevailing electron spin density is unambiguously localized on copper. The energetic preference of diaqua-Cu-(N7,O6-guanine) over triaqua-Cu-(N7-guanine) was found for the four-coordinate structures. However, the energy difference between these two conformations decreases with the number of water molecules present in the systems, and in complexes with five water molecules this preference is preserved only at DeltaG level where thermal and entropy terms are included.

Cyanide and Copper Recovery from Barren Solution of the Merrill Crowe Process

NASA Astrophysics Data System (ADS)

Parga, José R.; Valenzuela, Jesús L.; Díaz, J. A.

This paper is a brief overview of the role of inducing the nucleated precipitation of copper and cyanide in a flashtube serpentine reactor, using sodium sulfide as the precipitate and sulfuric acid as pH control. The results showed that pH had a great effect on copper cyanide removal efficiency and the optimum pH was about 3 to 3.5. At this pH value copper cyanide removal efficiency could be achieved above 97 and 99 %, when influent copper concentration ions were 650 and 900 ppm respectively. In this process the cyanide associated with the copper, zinc, iron cyanide complexes are released as HCN gas under strong acidic conditions, allowing it to be recycled back to the cyanidation process as free cyanide.

Studies on chalcone derivatives: complex formation, thermal behavior, stability constant and antioxidant activity.

PubMed

El-Sayed, Yusif S; Gaber, M

2015-02-25

The chalcone 3-[4'-dimethylaminophenyl]-1-(2-pyridyl) prop-2-en-1-one (DMAPP) and 3-(4'-diethylaminophenyl)-1-(2-pyridinyl) prop-2-en-1-one abbreviated as DEAPP have been synthesized and characterized with IR, (1)H NMR, (13)C NMR spectroscopic techniques as described previously (El-Daly et al., 2008; Gaber et al., 2009; El-Sayed, 2013). By using UV visible spectroscopy method the mole fraction ratio for copper with DMAPP and DEAPP complexes were determined and it was found to be 1:1. The stability constants of this complex have been determined by Job's method. The stability constant (Kf) of copper with DMAPP and DEAPP complexes in universal buffer pH=3.2 was determined to be 9.9×10(4) and 5.2×10(4) respectively. The effect of Cu(II) ion on the emission spectrum of the free chalcone is also assigned. Adherence to Beer's law and Ringbom optimum concentration ranges are determined. The thermal decomposition of the metal complexes is studied by TGA technique. The kinetic parameters like activation energy, pre-exponential factor and entropy of activation are estimated. The structure of complexes was energetically optimized through molecular mechanics applying MM(+) force field coupled with molecular dynamics simulation. The bond lengths and bond angles have been calculated to confirm the geometry of the ligands and their Cu(II) complexes. The mode of interaction of the chalcone to copper nanoparticles was studied. The apparent association constants of the colloidal copper nanoparticles:chalcone complexes in solution were evaluated using the spectral method and compared with the formation constant of the Cu(II) chalcone complexes. Antioxidant activity of these chalcones was evaluated by using 1,1'-diphenyl-2-picrylhydrazyl (DPPH) radicals scavenging method, which showed that the antioxidant activity of DMAPP has higher value than the DEAPP. Semi-empirical study results showed that DMAPP have higher dipole moment than DEAPP. Copyright © 2014 Elsevier B.V. All rights reserved.

Studies on chalcone derivatives: Complex formation, thermal behavior, stability constant and antioxidant activity

NASA Astrophysics Data System (ADS)

El-Sayed, Yusif S.; Gaber, M.

2015-02-01

The chalcone 3-[4‧-dimethylaminophenyl]-1-(2-pyridyl) prop-2-en-1-one (DMAPP) and 3-(4‧-diethylaminophenyl)-1-(2-pyridinyl) prop-2-en-1-one abbreviated as DEAPP have been synthesized and characterized with IR, 1H NMR, 13C NMR spectroscopic techniques as described previously (El-Daly et al., 2008; Gaber et al., 2009; El-Sayed, 2013). By using UV visible spectroscopy method the mole fraction ratio for copper with DMAPP and DEAPP complexes were determined and it was found to be 1:1. The stability constants of this complex have been determined by Job's method. The stability constant (Kf) of copper with DMAPP and DEAPP complexes in universal buffer pH = 3.2 was determined to be 9.9 × 104 and 5.2 × 104 respectively. The effect of Cu(II) ion on the emission spectrum of the free chalcone is also assigned. Adherence to Beer's law and Ringbom optimum concentration ranges are determined. The thermal decomposition of the metal complexes is studied by TGA technique. The kinetic parameters like activation energy, pre-exponential factor and entropy of activation are estimated. The structure of complexes was energetically optimized through molecular mechanics applying MM+ force field coupled with molecular dynamics simulation. The bond lengths and bond angles have been calculated to confirm the geometry of the ligands and their Cu(II) complexes. The mode of interaction of the chalcone to copper nanoparticles was studied. The apparent association constants of the colloidal copper nanoparticles:chalcone complexes in solution were evaluated using the spectral method and compared with the formation constant of the Cu(II) chalcone complexes. Antioxidant activity of these chalcones was evaluated by using 1,1‧-diphenyl-2-picrylhydrazyl (DPPHrad) radicals scavenging method, which showed that the antioxidant activity of DMAPP has higher value than the DEAPP. Semi-empirical study results showed that DMAPP have higher dipole moment than DEAPP [1].

Selective and Sensitive Fluorescent Detection of Picric Acid by New Pyrene and Anthracene Based Copper Complexes.

PubMed

Reddy, Kumbam Lingeshwar; Kumar, Anabathula Manoj; Dhir, Abhimanew; Krishnan, Venkata

2016-11-01

New pyrene and anthracene based copper complexes 4 and 7 respectively were designed, synthesized and characterized. The fluorescence behaviour of both 4 and 7 were evaluated towards nitro aromatics and anions. Both 4 and 7 possess high selectivity for the detection of well-known explosive picric acid (PA) by showing maximum fluorescence affinity. Furthermore, complex 4 showed similar sensing efficiency towards PA at different pH ranges. It was also used for real world applications, as illustrated by the very fast detection of PA from soil samples observed directly by naked eye.

Combined zebrafish-yeast chemical-genetic screens reveal gene-copper-nutrition interactions that modulate melanocyte pigmentation.

PubMed

Ishizaki, Hironori; Spitzer, Michaela; Wildenhain, Jan; Anastasaki, Corina; Zeng, Zhiqiang; Dolma, Sonam; Shaw, Michael; Madsen, Erik; Gitlin, Jonathan; Marais, Richard; Tyers, Mike; Patton, E Elizabeth

2010-01-01

Hypopigmentation is a feature of copper deficiency in humans, as caused by mutation of the copper (Cu(2+)) transporter ATP7A in Menkes disease, or an inability to absorb copper after gastric surgery. However, many causes of copper deficiency are unknown, and genetic polymorphisms might underlie sensitivity to suboptimal environmental copper conditions. Here, we combined phenotypic screens in zebrafish for compounds that affect copper metabolism with yeast chemical-genetic profiles to identify pathways that are sensitive to copper depletion. Yeast chemical-genetic interactions revealed that defects in intracellular trafficking pathways cause sensitivity to low-copper conditions; partial knockdown of the analogous Ap3s1 and Ap1s1 trafficking components in zebrafish sensitized developing melanocytes to hypopigmentation in low-copper environmental conditions. Because trafficking pathways are essential for copper loading into cuproproteins, our results suggest that hypomorphic alleles of trafficking components might underlie sensitivity to reduced-copper nutrient conditions. In addition, we used zebrafish-yeast screening to identify a novel target pathway in copper metabolism for the small-molecule MEK kinase inhibitor U0126. The zebrafish-yeast screening method combines the power of zebrafish as a disease model with facile genome-scale identification of chemical-genetic interactions in yeast to enable the discovery and dissection of complex multigenic interactions in disease-gene networks.

Toxicity and deficiency of copper in Elsholtzia splendens affect photosynthesis biophysics, pigments and metal accumulation.

PubMed

Peng, Hongyun; Kroneck, Peter M H; Küpper, Hendrik

2013-06-18

Elsholtzia splendens is a copper-tolerant plant species growing on copper deposits in China. Spatially and spectrally resolved kinetics of in vivo absorbance and chlorophyll fluorescence in mesophyll of E. splendens were used to investigate the copper-induced stress from deficiency and toxicity as well as the acclimation to excess copper stress. The plants were cultivated in nutrient solutions containing either Fe(III)-EDTA or Fe(III)-EDDHA. Copper toxicity affected light-acclimated electron flow much stronger than nonphotochemical quenching (NPQ) or dark-acclimated photochemical efficiency of PSIIRC (Fv/Fm). It also changed spectrally resolved Chl fluorescence kinetics, in particular by strengthening the short-wavelength (<700 nm) part of NPQ altering light harvesting complex II (LHCII) aggregation. Copper toxicity reduced iron accumulation, decreased Chls and carotenoids in leaves. During acclimation to copper toxicity, leaf copper decreased but leaf iron increased, with photosynthetic activity and pigments recovering to normal levels. Copper tolerance in E. splendens was inducible; acclimation seems be related to homeostasis of copper and iron in E. splendens. Copper deficiency appeared at 10 mg copper per kg leaf DW, leading to reduced growth and decreased photosynthetic parameters (F0, Fv/Fm, ΦPSII). The importance of these results for evaluating responses of phytoremediation plants to stress in their environment is discussed.

Release of Micronized Copper Particles from Pressure ...

EPA Pesticide Factsheets

Micronized copper pressure treated lumber (PTL) has recently been introduced to the consumer market as a replacement for ionized copper PTL. The presence of particulate rather than aqueous copper raises concerns about the exposure of humans as well as the environment to the particles. Two common pathways of exposure, leaching during contact with water and transfer during physical contact, were investigated to gage potential human and environmental risk during intended use of the product. Characterization, leaching tests, and wipe tests were conducted on two representative formulations of micronized copper PTL (micronized copper azole or MCA) to quantify the levels of copper present in the treated material and the amount of copper released during use as well as to determine the form (particle or ion) of the copper after it was released. Additionally, an ionized copper pressure treated wood (alkaline copper azole or ACA) was tested for comparison. The characterization showed that copper carbonate is the primary particle form in the MCA treated wood, but other forms are also present, particularly in the MCA-1 formulation, which contained a large amount of organically complexed copper. Microscopy showed that MCA-1 contained particles roughly half the size of MCA-2. The leaching results indicate that mostly (> ~95%) ionic copper is released from the MCA wood and that the particulate copper that was released is attached to cellulose and not free in solution. A sma

Geochemical prospecting for copper and nickel in the Wulgai and Tor Tangi areas southeast of Hindubagh, Quetta Division, Pakistan

USGS Publications Warehouse

Stanin, S. Anthony; Wahid, M.A.; Khan, Shamsher

1975-01-01

Showings of magnetite, copper, and possible nickel mineralization in the Hindubagh chromite mining district are near Wulgai and Tor Tangi. Several hundred samples of clastic material from dry streambeds in these areas were sieved for the minus-80-mesh fraction and analyzed for copper using 2, 2'-biquinoline and for nickel using alpha-furildioxime. The copper threshold is 75 ppm, and the nickel threshold is 400 ppm. A geochemical map has been prepared that shows nine areas of anomalously high copper and six areas of high nickel. The nickel anomalies may represent secondary dispersion patterns derived from the erosion of nickeliferous ultramafic rocks of the Hindubagh intrusive complex. Copper showings in and near four of the anomalous copper areas indicate that detailed geological investigation and detailed geochemical sampling of rocks, soil, and unconsolidated clastic material are required to determine the source of the anomalies.

Copper Homeostasis at the Host-Pathogen Interface*

PubMed Central

Hodgkinson, Victoria; Petris, Michael J.

2012-01-01

The trace element copper is indispensable for all aerobic life forms. Its ability to cycle between two oxidation states, Cu1+ and Cu2+, has been harnessed by a wide array of metalloenzymes that catalyze electron transfer reactions. The metabolic needs for copper are sustained by a complex series of transporters and carrier proteins that regulate its intracellular accumulation and distribution in both pathogenic microbes and their animal hosts. However, copper is also potentially toxic due in part to its ability to generate reactive oxygen species. Recent studies suggest that the macrophage phagosome accumulates copper during bacterial infection, which may constitute an important mechanism of killing. Bacterial countermeasures include the up-regulation of copper export and detoxification genes during infection, which studies suggest are important determinants of virulence. In this minireview, we summarize recent developments that suggest an emerging role for copper as an unexpected component in determining the outcome of host-pathogen interactions. PMID:22389498

Synthesis, characterization and biological activities of copper(II) complex of 2-Benzimidazolyl-urea and the nitrate salt of 2-Benzimidazolyl-urea

NASA Astrophysics Data System (ADS)

Poyraz, Mehmet; Sari, Musa; Banti, Christina N.; Hadjikakou, Sotiris K.

2017-10-01

The synthesis of the complex {[Cu(BZIMU)2](NO3)2} (1) (BZIMU = 2-Benzimidazolyl-urea) is reported here. The complex 1 was characterized by elemental analysis, FT-IR, magnetic susceptibility and molar conductance measurements. The crystal structures of 1 and of the nitrate salt of [(BZIMUH+)(NO3)-] (2) were determined by X-ray diffraction analysis. The copper complex 1 and [(BZIMUH+)(NO3)-] (2) were evaluated for their in vitro cytotoxic activity (cell viability) against human cervix adenocarcinoma (HeLa) and human breast adenocarcinoma (MCF-7) cell line and normal human fetal lung fibroblast cells (MRC-5) with SRB assay.

Spectroscopic studies on Solvatochromism of mixed-chelate copper(II) complexes using MLR technique

NASA Astrophysics Data System (ADS)

Golchoubian, Hamid; Moayyedi, Golasa; Fazilati, Hakimeh

2012-01-01

Mixed-chelate copper(II) complexes with a general formula [Cu(acac)(diamine)]X where acac = acetylacetonate ion, diamine = N,N-dimethyl,N'-benzyl-1,2-diaminoethane and X = BPh 4-, PF 6-, ClO 4- and BF 4- have been prepared. The complexes were characterized on the basis of elemental analysis, molar conductance, UV-vis and IR spectroscopies. The complexes are solvatochromic and their solvatochromism were investigated by visible spectroscopy. All complexes demonstrated the positive solvatochromism and among the complexes [Cu(acac)(diamine)]BPh 4·H 2O showed the highest Δ νmax value. To explore the mechanism of interaction between solvent molecules and the complexes, different solvent parameters such as DN, AN, α and β using multiple linear regression (MLR) method were employed. The statistical results suggested that the DN parameter of the solvent plays a dominate contribution to the shift of the d-d absorption band of the complexes.

Crystal and electronic structures of magnesium(II), copper(II), and mixed magnesium(II)-copper(II) complexes of the quinoline half of styrylquinoline-type HIV-1 integrase inhibitors.

PubMed

Courcot, B; Firley, D; Fraisse, B; Becker, P; Gillet, J-M; Pattison, P; Chernyshov, D; Sghaier, M; Zouhiri, F; Desmaële, D; d'Angelo, J; Bonhomme, F; Geiger, S; Ghermani, N E

2007-05-31

A new target in AIDS therapy development is HIV-1 integrase (IN). It was proven that HIV-1 IN required divalent metal cations to achieve phosphodiester bond cleavage of DNA. Accordingly, all newly investigated potent IN inhibitors contain chemical fragments possessing a high ability to chelate metal cations. One of the promising leads in the polyhydroxylated styrylquinolines (SQLs) series is (E)-8-hydroxy-2-[2-(4,5-dihydroxy-3-methoxyphenyl)-ethenyl]-7-quinoline carboxylic acid (1). The present study focuses on the quinoline-based progenitor (2), which is actually the most probable chelating part of SQLs. Conventional and synchrotron low-temperature X-ray crystallographic studies were used to investigate the chelating power of progenitor 2. Mg2+ and Cu2+ cations were selected for this purpose, and three types of metal complexes of 2 were obtained: Mg(II) complex (4), Cu(II) complex (5) and mixed Mg(II)-Cu(II) complexes (6 and 7). The analysis of the crystal structure of complex 4 indicates that two tridentate ligands coordinate two Mg2+ cations, both in octahedral geometry. The Mg-Mg distance was found equal to 3.221(1) A, in agreement with the metal-metal distance of 3.9 A encountered in the crystal structure of Escherichia coli DNA polymerase I. In 5, the complex is formed by two bidentate ligands coordinating one copper ion in tetrahedral geometry. Both mixed Mg(II)-Cu(II) complexes, 6 and 7 exhibit an original arrangement of four ligands linked to a central heterometallic cluster consisting of three octahedrally coordinated magnesium ions and one tetrahedrally coordinated copper ion. Quantum mechanics calculations were also carried out in order to display the electrostatic potential generated by the dianionic ligand 2 and complex 4 and to quantify the binding energy (BE) during the formation of the magnesium complex of progenitor 2. A comparison of the binding energies of two hypothetical monometallic Mg(II) complexes with that found in the bimetallic magnesium complex 4 was made.

Diagnosis of abnormal biliary copper excretion by positron emission tomography with targeting of 64Copper-asialofetuin complex in LEC rat model of Wilson’s disease

PubMed Central

Bahde, Ralf; Kapoor, Sorabh; Bhargava, Kuldeep K; Palestro, Christopher J; Gupta, Sanjeev

2014-01-01

Identification by molecular imaging of key processes in handling of transition state metals, such as copper (Cu), will be of considerable clinical value. For instance, the ability to diagnose Wilson’s disease with molecular imaging by identifying copper excretion in an ATP7B-dependent manner will be very significant. To develop highly effective diagnostic approaches, we hypothesized that targeting of radiocopper via the asialoglycoprotein receptor will be appropriate for positron emission tomography, and examined this approach in a rat model of Wilson’s disease. After complexing 64Cu to asialofetuin we studied handling of this complex compared with 64Cu in healthy LEA rats and diseased homozygous LEC rats lacking ATP7B and exhibiting hepatic copper toxicosis. We analyzed radiotracer clearance from blood, organ uptake, and biliary excretion, including sixty minute dynamic positron emission tomography recordings. In LEA rats, 64Cu-asialofetuin was better cleared from blood followed by liver uptake and greater biliary excretion than 64Cu. In LEC rats, 64Cu-asialofetuin activity cleared even more rapidly from blood followed by greater uptake in liver, but neither 64Cu-asialofetuin nor 64Cu appeared in bile. Image analysis demonstrated rapid visualization of liver after 64Cu-asialofetuin administration followed by decreased liver activity in LEA rats while liver activity progressively increased in LEC rats. Image analysis resolved this difference in hepatic activity within one hour. We concluded that 64Cu-asialofetuin complex was successfully targeted to the liver and radiocopper was then excreted into bile in an ATP7B-dependent manner. Therefore, hepatic targeting of radiocopper will be appropriate for improving molecular diagnosis and for developing drug/cell/gene therapies in Wilson’s disease. PMID:25250203

Effects of copper source and concentration on in vitro phytate phosphorus hydrolysis by phytase.

PubMed

Pang, Yanfang; Applegate, Todd J

2006-03-08

Five copper (Cu) sources were studied at pH 2.5, 5.5, and 6.5 to determine how Cu affects phytate phosphorus (PP) hydrolysis by phytase at concentrations up to 500 mg/kg diet (60 min, 40-41 degrees C). Subsequently, Cu solubility with and without sodium phytate was measured. Adding Cu inhibited PP hydrolysis at pH 5.5 and pH 6.5 (P < 0.05). This inhibition was greater with higher concentrations of Cu. Tri-basic copper chloride and copper lysinate inhibited PP hydrolysis much less than copper sulfate pentahydrate, copper chloride, and copper citrate (P < 0.05). A strong negative relationship was observed between PP hydrolysis and soluble Cu at pH 5.5 (r = -0.76, P < 0.0001) and 6.5 (r = -0.54, P < 0.0001). In conclusion, pH, Cu concentration, and source influenced PP hydrolysis by phytase in vitro and were related to the amount of soluble Cu and the formation of insoluble copper-phytin complexes.

Aspergillus fumigatus Copper Export Machinery and Reactive Oxygen Intermediate Defense Counter Host Copper-Mediated Oxidative Antimicrobial Offense.

PubMed

Wiemann, Philipp; Perevitsky, Adi; Lim, Fang Yun; Shadkchan, Yana; Knox, Benjamin P; Landero Figueora, Julio A; Choera, Tsokyi; Niu, Mengyao; Steinberger, Andrew J; Wüthrich, Marcel; Idol, Rachel A; Klein, Bruce S; Dinauer, Mary C; Huttenlocher, Anna; Osherov, Nir; Keller, Nancy P

2017-05-02

The Fenton-chemistry-generating properties of copper ions are considered a potent phagolysosome defense against pathogenic microbes, yet our understanding of underlying host/microbe dynamics remains unclear. We address this issue in invasive aspergillosis and demonstrate that host and fungal responses inextricably connect copper and reactive oxygen intermediate (ROI) mechanisms. Loss of the copper-binding transcription factor AceA yields an Aspergillus fumigatus strain displaying increased sensitivity to copper and ROI in vitro, increased intracellular copper concentrations, decreased survival in challenge with murine alveolar macrophages (AMΦs), and reduced virulence in a non-neutropenic murine model. ΔaceA survival is remediated by dampening of host ROI (chemically or genetically) or enhancement of copper-exporting activity (CrpA) in A. fumigatus. Our study exposes a complex host/microbe multifactorial interplay that highlights the importance of host immune status and reveals key targetable A. fumigatus counter-defenses. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

New copper complexes with bipyrazolic ligands: Synthesis, characterization and evaluation of the antibacterial and catalytic properties

NASA Astrophysics Data System (ADS)

Harit, Tarik; Abouloifa, Houssam; Tillard, Monique; Eddike, Driss; Asehraou, Abdeslam; Malek, Fouad

2018-07-01

The synthesis of new bipyrazolic ligands functionalized by carboxyl groups, namely 3-Bis(3‧-carboxyl-5‧-methyl-l'-pyrazolyl) propan-2-ol (L1) and 1,3-Bis(3‧-carboxyl-5‧-methyl-l '-pyrazolyl),2-methyl propane (L2) is reported. Their corresponding [C13H15CuN4O5] (CuL1) and [C14H16CuN4O4] (CuL2) copper (II) complexes are also elaborated and characterized by elemental analysis, FTIR an UV-visible spectroscopy. The crystal structure of the CuL1 complex confirms that copper atom is 4-coordinated, in a distorted square planar geometry within the molecule, and achieves its coordination through weak intermolecular interactions leading to two dimensional slabs. This geometry is in agreement with UV-visible results which also evidence that structure of complexes are affected in DMSO in contrast to methanol. No antibacterial activity against all the tested bacterial strains has been found for the Cu (II) complexes. By contrast, CuL1 is characterized with good catalytic properties in the air-oxidation of catechol substrate to quinone.

Forming Refractory Insulation On Copper Wire

NASA Technical Reports Server (NTRS)

Setlock, J.; Roberts, G.

1995-01-01

Alternative insulating process forms flexible coat of uncured refractory insulating material on copper wire. Coated wire formed into coil or other complex shape. Wire-coating apparatus forms "green" coat on copper wire. After wire coiled, heating converts "green" coat to refractory electrical insulator. When cured to final brittle form, insulating material withstands temperatures above melting temperature of wire. Process used to make coils for motors, solenoids, and other electrical devices to be operated at high temperatures.

Copper Solubility and Speciation in Mineral-Buffered Fluids at Crust to Upper Mantle Conditions

NASA Astrophysics Data System (ADS)

Hack, A. C.; Mavrogenes, J. A.; Berry, A. J.

2003-12-01

Fluid inclusions, synthesised in a piston-cylinder apparatus, were used to trap representative high P-T fluid samples under mineral-buffered conditions in the systems Cu2O-MgO-SiO2-HCl-H2O and Cu-K2O-Al2O3-SiO2-Fe3O4-Fe2O3-HCl-H2O at up to 850° C and 1.7 GPa, and as a function of salinity to 11 mol/kg Cl. Copper solubility and speciation were obtained by analysing individual fluid inclusions by excimer laser ablation inductively coupled mass spectrometry (LA-ICP-MS), proton induced X-ray emission (PIXE) and Cu K-edge X-ray absorption near edge structure (XANES) spectroscopy. Quenched capsule fluids were also analysed. At 710° C copper-cuprite-talc-quartz solubility in aqueous fluid containing 1 mol/kg Cl increases with P to at least 1.7 GPa. Conspicuously, with increasing P (> ˜ 0.5 GPa) talc solubility increases and molal Cu concentrations exceed those of Cl. Isothermal Cu solubility appears to mimic the solubility isopleths in the SiO2-H2O system. Solubility trends suggest that the stability field of copper(I) hydroxide complexes (e.g. Cu(OH)aq) expands to higher salinities such that H2O may become an effective ligand at high-P. At constant P (e.g. 0.35 GPa) solubility decreases with increasing T (i.e. > 525° C). High-T Cu K-edge XANES spectra of single homogenised synthetic fluid inclusions indicate that highly coordinated chlorocopper(I) complexes (e.g. Cu:Cl, 1:3 to 4) predominate at high salinity, whereas lower-order linear Cu-Cl coordination predominates at lower salinities, in fluids buffered by quartz-talc-copper-cuprite. This is consistent with the interpretation of the solubility data. At equivalent salinity, T and P conditions, spectra for fluids buffered by native copper-orthoclase-sillimanite-quartz-magnetite-hematite show no evidence for higher-order chlorocopper(I) complexes. Preliminary extended X-ray absorption fine structure data for these latter inclusions indicate that [CuCl2]- predominates. The stability of higher-order complexes is strongly coupled to HCl concentrations, which at constant P and T is determined by both the specific mineral assemblage and total salinity. This is the first spectroscopic evidence for highly coordinated chlorocopper(I) complexes in supercritical fluids. Furthermore, the speciation dependence on the buffering mineral assemblage has not been recognized previously. Similarly, this is the first experimental confirmation that copper concentrations in mineral-buffered fluids can be extremely high, e.g. ˜ 10 wt%, substantiating inferences based on natural fluid inclusions associated with porphyry copper ore deposits.

Studies of EXAFSSpectra using Copper (II) Schiff Base complexes and Determination of Bond lengths Using Synchrotron Radiation

NASA Astrophysics Data System (ADS)

Mishra, A.; Vibhute, V.; Ninama, S.; Parsai, N.; Jha, S. N.; Sharma, P.

2016-10-01

X-ray absorption fine structure (XAFS) at the K-edge of copper has been studied in some copper (II) complexes with substituted anilines like (2Cl, 4Br, 2NO2, 4NO2 and pure aniline) with o-PDA (orthophenylenediamine) as ligand. The X-ray absorption measurements have been performed at the recently developed BL-8 dispersive EXAFS beam line at 2.5 GeV Indus-2 Synchrotron Source at RRCAT, Indore, India. The data obtained has been processed using EXAFS data analysis program Athena.The graphical method gives the useful information about bond length and also the environment of the absorbing atom. The theoretical bond lengths of the complexes were calculated by using interactive fitting of EXAFS using fast Fourier inverse transformation (IFEFFIT) method. This method is also called as Fourier transform method. The Lytle, Sayers and Stern method and Levy's method have been used for determination of bond lengths experimentally of the studied complexes. The results of both methods have been compared with theoretical IFEFFIT method.

Photoelectron and computational studies of the copper-nucleoside anionic complexes, Cu(-)(cytidine) and Cu(-)(uridine).

PubMed

Li, Xiang; Ko, Yeon-Jae; Wang, Haopeng; Bowen, Kit H; Guevara-García, Alfredo; Martínez, Ana

2011-02-07

The copper-nucleoside anions, Cu(-)(cytidine) and Cu(-)(uridine), have been generated in the gas phase and studied by both experimental (anion photoelectron spectroscopy) and theoretical (density functional calculations) methods. The photoelectron spectra of both systems are dominated by single, intense, and relatively narrow peaks. These peaks are centered at 2.63 and 2.71 eV for Cu(-)(cytidine) and Cu(-)(uridine), respectively. According to our calculations, Cu(-)(cytidine) and Cu(-)(uridine) species with these peak center [vertical detachment energy (VDE)] values correspond to structures in which copper atomic anions are bound to the sugar portions of their corresponding nucleosides largely through electrostatic interactions; the observed species are anion-molecule complexes. The combination of experiment and theory also reveal the presence of a slightly higher energy, anion-molecule complex isomer in the case of the Cu(-)(cytidine). Furthermore, our calculations found that chemically bond isomers of these species are much more stable than their anion-molecule complex counterparts, but since their calculated VDE values are larger than the photon energy used in these experiments, they were not observed.

Photoelectron and computational studies of the copper-nucleoside anionic complexes, Cu-(cytidine) and Cu-(uridine)

NASA Astrophysics Data System (ADS)

Li, Xiang; Ko, Yeon-Jae; Wang, Haopeng; Bowen, Kit H.; Guevara-García, Alfredo; Martínez, Ana

2011-02-01

The copper-nucleoside anions, Cu-(cytidine) and Cu-(uridine), have been generated in the gas phase and studied by both experimental (anion photoelectron spectroscopy) and theoretical (density functional calculations) methods. The photoelectron spectra of both systems are dominated by single, intense, and relatively narrow peaks. These peaks are centered at 2.63 and 2.71 eV for Cu-(cytidine) and Cu-(uridine), respectively. According to our calculations, Cu-(cytidine) and Cu-(uridine) species with these peak center [vertical detachment energy (VDE)] values correspond to structures in which copper atomic anions are bound to the sugar portions of their corresponding nucleosides largely through electrostatic interactions; the observed species are anion-molecule complexes. The combination of experiment and theory also reveal the presence of a slightly higher energy, anion-molecule complex isomer in the case of the Cu-(cytidine). Furthermore, our calculations found that chemically bond isomers of these species are much more stable than their anion-molecule complex counterparts, but since their calculated VDE values are larger than the photon energy used in these experiments, they were not observed.

Inhibition of cyclin-dependent kinase CDK1 by oxindolimine ligands and corresponding copper and zinc complexes.

PubMed

Miguel, Rodrigo Bernardi; Petersen, Philippe Alexandre Divina; Gonzales-Zubiate, Fernando A; Oliveira, Carla Columbano; Kumar, Naresh; do Nascimento, Rafael Rodrigues; Petrilli, Helena Maria; da Costa Ferreira, Ana Maria

2015-10-01

Oxindolimine-copper(II) and zinc(II) complexes that previously have shown to induce apoptosis, with DNA and mitochondria as main targets, exhibit here significant inhibition of kinase CDK1/cyclin B protein. Copper species are more active than the corresponding zinc, and the free ligand shows to be less active, indicating a major influence of coordination in the process, and a further modulation by the coordinated ligand. Molecular docking and classical molecular dynamics provide a better understanding of the effectiveness and kinase inhibition mechanism by these compounds, showing that the metal complex provides a stronger interaction than the free ligand with the ATP-binding site. The metal ion introduces charge in the oxindole species, giving it a more rigid conformation that then becomes more effective in its interactions with the protein active site. Analogous experiments resulted in no significant effect regarding phosphatase inhibition. These results can explain the cytotoxicity of these metal complexes towards different tumor cells, in addition to its capability of binding to DNA, and decreasing membrane potential of mitochondria.

Investigating the influence of standard staining procedures on the copper distribution and concentration in Wilson's disease liver samples by laser ablation-inductively coupled plasma-mass spectrometry.

PubMed

Hachmöller, Oliver; Aichler, Michaela; Schwamborn, Kristina; Lutz, Lisa; Werner, Martin; Sperling, Michael; Walch, Axel; Karst, Uwe

2017-12-01

The influence of rhodanine and haematoxylin and eosin (HE) staining on the copper distribution and concentration in liver needle biopsy samples originating from patients with Wilson's disease (WD), a rare autosomal recessive inherited disorder of the copper metabolism, is investigated. In contemporary diagnostic of WD, rhodanine staining is used for histopathology, since rhodanine and copper are forming a red to orange-red complex, which can be recognized in the liver tissue using a microscope. In this paper, a laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) method is applied for the analysis of eight different WD liver samples. Apart from a spatially resolved elemental detection as qualitative information, this LA-ICP-MS method offers also quantitative information by external calibration with matrix-matched gelatine standards. The sample set of this work included an unstained and a rhodanine stained section of each WD liver sample. While unstained sections of WD liver samples showed very distinct structures of the copper distribution with high copper concentrations, rhodanine stained sections revealed a blurred copper distribution with significant decreased concentrations in a range from 20 to more than 90%. This implies a copper removal from the liver tissue by complexation during the rhodanine staining. In contrast to this, a further HE stained sample of one WD liver sample did not show a significant decrease in the copper concentration and influence on the copper distribution in comparison to the unstained section. Therefore, HE staining can be combined with the analysis by means of LA-ICP-MS in two successive steps from one thin section of a biopsy specimen. This allows further information to be gained on the elemental distribution by LA-ICP-MS additional to results obtained by histological staining. Copyright © 2017 Elsevier GmbH. All rights reserved.

The cardiac copper chaperone proteins Sco1 and CCS are up-regulated, but Cox 1 and Cox4 are down-regulated, by copper deficiency.

PubMed

Getz, Jean; Lin, Dingbo; Medeiros, Denis M

2011-10-01

Copper is ferried in a cell complexed to chaperone proteins, and in the heart much copper is required for cytochrome c oxidase (Cox). It is not completely understood how copper status affects the levels of these proteins. Here we determined if dietary copper deficiency could up- or down-regulate select copper chaperone proteins and Cox subunits 1 and 4 in cardiac tissue of rats. Sixteen weanling male Long-Evans rats were randomized into treatment groups, one group receiving a copper-deficient diet (<1 mg Cu/kg diet) and one group receiving a diet containing adequate copper (6 mg Cu/kg diet) for 5 weeks. Hearts were removed, weighed, and non-myofibrillar proteins separated to analyze for levels of CCS, Sco1, Ctr1, Cox17, Cox1, and Cox4 by SDS-PAGE and Western blotting. No changes were observed in the concentrations of CTR1 and Cox17 between copper-adequate and copper-deficient rats. CCS and Sco1 were up-regulated and Cox1 and Cox4 were both down-regulated as a result of copper deficiency. These data suggest that select chaperone proteins and may be up-regulated, and Cox1 and 4 down-regulated, by a dietary copper deficiency, whereas others appear not to be affected by copper status.

Electroencephalographic Fractal Dimension in Healthy Ageing and Alzheimer’s Disease

PubMed Central

Cottone, Carlo; Cancelli, Andrea; Rossini, Paolo Maria; Tecchio, Franca

2016-01-01

Brain activity is complex; a reflection of its structural and functional organization. Among other measures of complexity, the fractal dimension is emerging as being sensitive to neuronal damage secondary to neurological and psychiatric diseases. Here, we calculated Higuchi’s fractal dimension (HFD) in resting-state eyes-closed electroencephalography (EEG) recordings from 41 healthy controls (age: 20–89 years) and 67 Alzheimer’s Disease (AD) patients (age: 50–88 years), to investigate whether HFD is sensitive to brain activity changes typical in healthy aging and in AD. Additionally, we considered whether AD-accelerating effects of the copper fraction not bound to ceruloplasmin (also called “free” copper) are reflected in HFD fluctuations. The HFD measure showed an inverted U-shaped relationship with age in healthy people (R2 = .575, p < .001). Onset of HFD decline appeared around the age of 60, and was most evident in central-parietal regions. In this region, HFD decreased with aging stronger in the right than in the left hemisphere (p = .006). AD patients demonstrated reduced HFD compared to age- and education-matched healthy controls, especially in temporal-occipital regions. This was associated with decreasing cognitive status as assessed by mini-mental state examination, and with higher levels of non-ceruloplasmin copper. Taken together, our findings show that resting-state EEG complexity increases from youth to maturity and declines in healthy, aging individuals. In AD, brain activity complexity is further reduced in correlation with cognitive impairment. In addition, elevated levels of non-ceruloplasmin copper appear to accelerate the reduction of neural activity complexity. Overall, HDF appears to be a proper indicator for monitoring EEG-derived brain activity complexity in healthy and pathological aging. PMID:26872349

Influence of Copper Resistance Determinants on Gold Transformation by Cupriavidus metallidurans Strain CH34

PubMed Central

Wiesemann, Nicole; Mohr, Juliane; Grosse, Cornelia; Herzberg, Martin; Hause, Gerd; Reith, Frank

2013-01-01

Cupriavidus metallidurans is associated with gold grains and may be involved in their formation. Gold(III) complexes influence the transcriptome of C. metallidurans (F. Reith et al., Proc. Natl. Acad. Sci. U. S. A. 106:17757–17762, 2009), leading to the upregulation of genes involved in the detoxification of reactive oxygen species and metal ions. In a systematic study, the involvement of these systems in gold transformation was investigated. Treatment of C. metallidurans cells with Au(I) complexes, which occur in this organism's natural environment, led to the upregulation of genes similar to those observed for treatment with Au(III) complexes. The two indigenous plasmids of C. metallidurans, which harbor several transition metal resistance determinants, were not involved in resistance to Au(I/III) complexes nor in their transformation to metallic nanoparticles. Upregulation of a cupA-lacZ fusion by the MerR-type regulator CupR with increasing Au(III) concentrations indicated the presence of gold ions in the cytoplasm. A hypothesis stating that the Gig system detoxifies gold complexes by the uptake and reduction of Au(III) to Au(I) or Au(0) reminiscent to detoxification of Hg(II) was disproven. ZupT and other secondary uptake systems for transition metal cations influenced Au(III) resistance but not the upregulation of the cupA-lacZ fusion. The two copper-exporting P-type ATPases CupA and CopF were also not essential for gold resistance. The copABCD determinant on chromosome 2, which encodes periplasmic proteins involved in copper resistance, was required for full gold resistance in C. metallidurans. In conclusion, biomineralization of gold particles via the reduction of mobile Au(I/III) complexes in C. metallidurans appears to primarily occur in the periplasmic space via copper-handling systems. PMID:23475973

Interaction of a common painkiller piroxicam and copper-piroxicam with chromatin causes structural alterations accompanied by modulation at the epigenomic/genomic level.

PubMed

Goswami, Sathi; Sanyal, Sulagna; Chakraborty, Payal; Das, Chandrima; Sarkar, Munna

2017-08-01

NSAIDs are the most common class of painkillers and anti-inflammatory agents. They also show other functions like chemoprevention and chemosuppression for which they act at the protein but not at the genome level since they are mostly anions at physiological pH, which prohibit their approach to the poly-anionic DNA. Complexing the drugs with bioactive metal obliterate their negative charge and allow them to bind to the DNA, thereby, opening the possibility of genome level interaction. To test this hypothesis, we present the interaction of a traditional NSAID, Piroxicam and its copper complex with core histone and chromatin. Spectroscopy, DLS, and SEM studies were applied to see the effect of the interaction on the structure of histone/chromatin. This was coupled with MTT assay, immunoblot analysis, confocal microscopy, micro array analysis and qRT-PCR. The interaction of Piroxicam and its copper complex with histone/chromatin results in structural alterations. Such structural alterations can have different biological manifestations, but to test our hypothesis, we have focused only on the accompanied modulations at the epigenomic/genomic level. The complex, showed alteration of key epigenetic signatures implicated in transcription in the global context, although Piroxicam caused no significant changes. We have correlated such alterations caused by the complex with the changes in global gene expression and validated the candidate gene expression alterations. Our results provide the proof of concept that DNA binding ability of the copper complexes of a traditional NSAID, opens up the possibility of modulations at the epigenomic/genomic level. Copyright © 2017 Elsevier B.V. All rights reserved.

Mixed copper-platinum complex formation could explain synergistic antiproliferative effect exhibited by binary mixtures of cisplatin and copper-1,10-phenanthroline compounds: An ESI-MS study.

PubMed

Pivetta, Tiziana; Lallai, Viola; Valletta, Elisa; Trudu, Federica; Isaia, Francesco; Perra, Daniela; Pinna, Elisabetta; Pani, Alessandra

2015-10-01

Cisplatin, cis-diammineplatinum(II) dichloride, is a metal complex used in clinical practice for the treatment of cancer. Despite its great efficacy, it causes adverse reactions and most patients develop a resistance to cisplatin. To overcome these issues, a multi-drug therapy was introduced as a modern approach to exploit the drug synergy. A synergistic effect had been previously found when testing binary combinations of cisplatin and three copper complexes in vitro, namely, Cu(phen)(OH2)2(OClO3)2, [Cu(phen)2(OH2)](ClO4)2 and [Cu(phen)2(H2dit)](ClO4)2,(phen=1,10-phenanthroline, H2dit=imidazolidine-2-thione), against the human acute T-lymphoblastic leukaemia cell line (CCRF-CEM). In this work [Cu(phen)2(OH2)](ClO4)2 was also tested in combination with cisplatin against cisplatin-resistant sublines of CCRF-CEM (CCRF-CEM-res) and ovarian (A2780-res) cancer cell lines. The tested combinations show a synergistic effect against both the types of resistant cells. The possibility that this effect was caused by the formation of new adducts was considered and mass spectra of solutions containing cisplatin and one of the three copper complexes at a time were measured using electrospray ionisation at atmospheric-pressure mass spectrometry (ESI-MS). A mixed complex was detected and its stoichiometry was assessed on the basis of the isotopic pattern and the results of tandem mass spectrometry experiments. The formed complex was found to be [Cu(phen)(OH)μ-(Cl)2Pt(NH3)(H2O)](+). Copyright © 2015 Elsevier Inc. All rights reserved.

Modeling MIC copper release from drinking water pipes.

PubMed

Pizarro, Gonzalo E; Vargas, Ignacio T; Pastén, Pablo A; Calle, Gustavo R

2014-06-01

Copper is used for household drinking water distribution systems given its physical and chemical properties that make it resistant to corrosion. However, there is evidence that, under certain conditions, it can corrode and release unsafe concentrations of copper to the water. Research on drinking water copper pipes has developed conceptual models that include several physical-chemical mechanisms. Nevertheless, there is still a necessity for the development of mathematical models of this phenomenon, which consider the interaction among physical-chemical processes at different spatial scales. We developed a conceptual and a mathematical model that reproduces the main processes in copper release from copper pipes subject to stagnation and flow cycles, and corrosion is associated with biofilm growth on the surface of the pipes. We discuss the influence of the reactive surface and the copper release curves observed. The modeling and experimental observations indicated that after 10h stagnation, the main concentration of copper is located close to the surface of the pipe. This copper is associated with the reactive surface, which acts as a reservoir of labile copper. Thus, for pipes with the presence of biofilm the complexation of copper with the biomass and the hydrodynamics are the main mechanisms for copper release. Copyright © 2013 Elsevier B.V. All rights reserved.

40 CFR Appendix B to Part 414 - Complexed Metal-Bearing Waste Streams

Code of Federal Regulations, 2010 CFR

2010-07-01

..., metallized/Azo dye + metal acetate Direct dyes, Azo Disperse dyes, Azo and Vat Organic pigment Green 7/Copper phthalocyanine Organic pigments Organic pigments/Phthalocyanine pigments Organic pigments/Copper phthalocyanine (Blue Crude) Organic pigments, miscellaneous lakes and toners Lead Organic pigments, Quinacridines...

40 CFR Appendix B to Part 414 - Complexed Metal-Bearing Waste Streams

Code of Federal Regulations, 2011 CFR

2011-07-01

..., metallized/Azo dye + metal acetate Direct dyes, Azo Disperse dyes, Azo and Vat Organic pigment Green 7/Copper phthalocyanine Organic pigments Organic pigments/Phthalocyanine pigments Organic pigments/Copper phthalocyanine (Blue Crude) Organic pigments, miscellaneous lakes and toners Lead Organic pigments, Quinacridines...

Proton and metal ion binding to natural organic polyelectrolytes-II. Preliminary investigation with a peat and a humic acid

USGS Publications Warehouse

Marinsky, J.A.; Reddy, M.M.

1984-01-01

We summarize here experimental studies of proton and metal ion binding to a peat and a humic acid. Data analysis is based on a unified physico-chemical model for reaction of simple ions with polyelectrolytes employing a modified Henderson-Hasselbalch equation. Peat exhibited an apparent intrinsic acid dissociation constant of 10-4.05, and an apparent intrinsic metal ion binding constant of: 400 for cadmium ion; 600 for zinc ion; 4000 for copper ion; 20000 for lead ion. A humic acid was found to have an apparent intrinsic proton binding constant of 10-2.6. Copper ion binding to this humic acid sample occurred at two types of sites. The first site exhibited reaction characteristics which were independent of solution pH and required the interaction of two ligands on the humic acid matrix to simultaneously complex with each copper ion. The second complex species is assumed to be a simple monodentate copper ion-carboxylate species with a stability constant of 18. ?? 1984.

Transferring the entatic-state principle to copper photochemistry

NASA Astrophysics Data System (ADS)

Dicke, B.; Hoffmann, A.; Stanek, J.; Rampp, M. S.; Grimm-Lebsanft, B.; Biebl, F.; Rukser, D.; Maerz, B.; Göries, D.; Naumova, M.; Biednov, M.; Neuber, G.; Wetzel, A.; Hofmann, S. M.; Roedig, P.; Meents, A.; Bielecki, J.; Andreasson, J.; Beyerlein, K. R.; Chapman, H. N.; Bressler, C.; Zinth, W.; Rübhausen, M.; Herres-Pawlis, S.

2018-03-01

The entatic state denotes a distorted coordination geometry of a complex from its typical arrangement that generates an improvement to its function. The entatic-state principle has been observed to apply to copper electron-transfer proteins and it results in a lowering of the reorganization energy of the electron-transfer process. It is thus crucial for a multitude of biochemical processes, but its importance to photoactive complexes is unexplored. Here we study a copper complex—with a specifically designed constraining ligand geometry—that exhibits metal-to-ligand charge-transfer state lifetimes that are very short. The guanidine-quinoline ligand used here acts on the bis(chelated) copper(I) centre, allowing only small structural changes after photoexcitation that result in very fast structural dynamics. The data were collected using a multimethod approach that featured time-resolved ultraviolet-visible, infrared and X-ray absorption and optical emission spectroscopy. Through supporting density functional calculations, we deliver a detailed picture of the structural dynamics in the picosecond-to-nanosecond time range.

Mononuclear late first row transition metal complexes of ONO donor hydrazone ligand: Synthesis, characterization, crystallographic insight, in vivo and in vitro anti-inflammatory activity

NASA Astrophysics Data System (ADS)

Kendur, Umashri; Chimmalagi, Geeta H.; Patil, Sunil M.; Gudasi, Kalagouda B.; Frampton, Christopher S.; Mangannavar, Chandrashekhar V.; Muchchandi, Iranna S.

2018-02-01

Air and moisture stable coordination compounds of late first row transition metal ions, viz., Co(II), Ni(II), Cu(II) and Zn(II) with a newly designed ligand, (E)-2-amino-N'-(1-(2-hydroxy-6-methyl-4-oxo-4H-pyran-3-yl)ethylidene)benzohydrazide (H2L) were prepared and extensively characterized using various spectro-analytical techniques. The ligand acts both in mono as well as doubly deprotonated manner. The ligand to metal stoichiometry was found to be 1:2 in case of complexes using chloride salts, whereas 1:1 in case of copper (II) complex using its acetate salt. The molecular structures of H2L, nickel and copper complexes were unambiguously determined by single-crystal X-ray diffraction studies reveal that H2L exists in a zwitterionic form while copper complex has copper centre in a distorted square planar environment. On the other hand, cobalt, nickel and zinc complexes display distorted octahedral coordination around the metal ion. In case of [Ni(HL)2].H2O, intramolecular Csbnd H⋯π stacking interaction were observed between the centroid of five membered chelate ring and phenyl proton C5sbnd H5 and intermolecular Csbnd H⋯π stacking interaction between the centroid of phenyl ring, dehydroacetic acid (DHA) ring and phenyl protons. The [Cu(L)DMF] complex is stabilized by intramolecular hydrogen bonding N1H⋯N2 and by intermolecular hydrogen bonding N1H⋯O4. Intermolecular interactions were investigated by Hirshfeld surfaces. Further, H2L and its metal complexes were screened for their in vivo and in vitro anti-inflammatory activities. The activity of the ligand has enhanced on coordination with transition metals. The tested compounds have shown excellent activity, which is almost equipotent to the standard used in the study.

Synthesis, spectral, thermal and antimicrobial studies on cobalt(II), nickel(II), copper(II), zinc(II) and palladium(II) complexes containing thiosemicarbazone ligand

NASA Astrophysics Data System (ADS)

El-Sawaf, Ayman K.; El-Essawy, Farag; Nassar, Amal A.; El-Samanody, El-Sayed A.

2018-04-01

The coordination characteristic of new N4-morpholinyl isatin-3-thiosemicarbazone (HL) towards Co(II), Ni(II), Cu(II), Zn(II) and Pd(II) has been studies. The structures of the complexes were described by elemental analyses, molar conductivity, magnetic, thermal and spectral (IR, UV-Vis, 1H and 13C NMR and ESR) studies. On the basis of analytical and spectral studies the ligand behaves as monobasic tridentate ONS donor forming two five membered rings towards cobalt, copper and palladium and afforded complexes of the kind [M(L)X], (Mdbnd Co, Cu or Pd; Xdbnd Cl, Br or OAc). Whereas the ligand bound to NiCl2 as neutral tridentate ONS donor and with ZnCl2 as neutral bidentate NS donor. The newly synthesized thiosemicarbazone ligand and some of its complexes were examined for antimicrobial activity against 2 gram negative bacterial strains (Escherichia coli Pseudomonas and aeruginosa), 2 gram positive bacterial strains (Streptococcus pneumoniae and Staphylococcus aureus)} and two Pathogenic fungi (Aspergillus fumigatus and Candida albicans). All metal complexes possess higher antimicrobial activity comparing with the free thiosemicarbazone ligand. The high potent activities of the complexes may arise from the coordination and chelation, which tends to make metal complexes act as more controlling and potent antimicrobial agents, thus hindering the growing of the microorganisms. The antimicrobial results also show that copper bromide complex is better antimicrobial agent as compared to the Schiff base and its metal complexes.

Quantum electron tunneling in respiratory complex I.

PubMed

Hayashi, Tomoyuki; Stuchebrukhov, Alexei A

2011-05-12

We have simulated the atomistic details of electronic wiring of all Fe/S clusters in complex I, a key enzyme in the respiratory electron transport chain. The tunneling current theory of many-electron systems is applied to the broken-symmetry (BS) states of the protein at the ZINDO level. While the one-electron tunneling approximation is found to hold in electron tunneling between the antiferromagnetic binuclear and tetranuclear Fe/S clusters without major orbital or spin rearrangement of the core electrons, induced polarization of the core electrons contributes significantly to decrease the electron transfer rates to 19-56 %. Calculated tunneling energy is about 3 eV higher than Fermi level in the band gap of the protein, which supports that the mechanism of electron transfer is quantum mechanical tunneling, as in the rest of the electron transport chain. Resulting electron tunneling pathways consist of up to three key contributing protein residues between neighboring Fe/S clusters. A signature of the wave properties of electrons is observed as distinct quantum interferences when multiple tunneling pathways exist. In N6a-N6b, electron tunnels along different pathways depending on the involved BS states, suggesting possible fluctuations of the tunneling pathways driven by the local protein environment. The calculated distance dependence of the electron transfer rates with internal water molecules included is in good agreement with a reported phenomenological relation.

Electrochemical and optical characterization of cobalt, copper and zinc phthalocyanine complexes.

PubMed

Lee, Jaehyun; Kim, Se Hun; Lee, Woosung; Lee, Jiwon; An, Byeong-Kwan; Oh, Se Young; Kim, Jae Pil; Park, Jongwook

2013-06-01

New phthalocyanine (Pc) derivatives that include the alkyl group in ligand were synthesized based on three core metals such as zinc (Zn), copper (Cu), and cobalt (Co). Electrochemical behaviors and optical properties of the new phthalocyanine derivatives with ligand and different core metal were investigated by using cyclic voltammetry, UV-Visible (UV-Vis) spectroscopy and photoluminescence (PL) spectroscopy. In UV-Vis data, maximum values of 2H, Co, Cu, and Zn complexes were 708 nm and 677 nm, 686 nm, 684 nm, respectively.

Lead isotope compositions of Late Cretaceous and early Tertiary igneous rocks and sulfide minerals in Arizona: Implications for the sources of plutons and metals in porphyry copper deposits

USGS Publications Warehouse

Bouse, R.M.; Ruiz, J.; Titley, S.R.; Tosdal, R.M.; Wooden, J.L.

1999-01-01

Porphyry copper deposits in Arizona are genetically associated with Late Cretaceous and early Tertiary igneous complexes that consist of older intermediate volcanic rocks and younger intermediate to felsic intrusions. The igneous complexes and their associated porphyry copper deposits were emplaced into an Early Proterozoic basement characterized by different rocks, geologic histories, and isotopic compositions. Lead isotope compositions of the Proterozoic basement rocks define, from northwest to southeast, the Mojave, central Arizona, and southeastern Arizona provinces. Porphyry copper deposits are present in each Pb isotope province. Lead isotope compositions of Late Cretaceous and early Tertiary plutons, together with those of sulfide minerals in porphyry copper deposits and of Proterozoic country rocks, place important constraints on genesis of the magmatic suites and the porphyry copper deposits themselves. The range of age-corrected Pb isotope compositions of plutons in 12 Late Cretaceous and early Tertiary igneous complexes is 206Pb/204Pb = 17.34 to 22.66, 207Pb/204Pb = 15.43 to 15.96, and 208Pb/204Pb = 37.19 to 40.33. These Pb isotope compositions and calculated model Th/U are similar to those of the Proterozoic rocks in which the plutons were emplaced, thereby indicating that Pb in the younger rocks and ore deposits was inherited from the basement rocks and their sources. No Pb isotope differences distinguish Late Cretaceous and early Tertiary igneous complexes that contain large economic porphyry copper deposits from less rich or smaller deposits that have not been considered economic for mining. Lead isotope compositions of Late Cretaceous and early Tertiary plutons and sulfide minerals from 30 metallic mineral districts, furthermore, require that the southeastern Arizona Pb province be divided into two subprovinces. The northern subprovince has generally lower 206Pb/204Pb and higher model Th/U, and the southern subprovince has higher 206Pb/204Pb and lower model Th/U. These Pb isotope differences are inferred to result from differences in their respective post-1.7 Ga magmatic histories. Throughout Arizona, Pb isotope compositions of Late Cretaceous and early Tertiary plutons and associated sulfide minerals are distinct from those of Jurassic plutons and also middle Tertiary igneous rocks and sulfide minerals. These differences most likely reflect changes in tectonic setting and magmatic sources. Within Late Cretaceous and early Tertiary igneous complexes that host economic porphyry copper deposits, there is commonly a decrease in Pb isotope composition from older to younger plutons. This decrease in Pb isotope values with time suggests an increasing involvement of crust with lower U/Pb than average crust in the source(s) of Late Cretaceous and early Tertiary magmas. Lead isotope compositions of the youngest porphyries in the igneous complexes are similar to those in most sulfide minerals within the associated porphyry copper deposit. This Pb isotope similarity argues for a genetic link between them. However, not all Pb in the sulfide minerals in porphyry copper deposits is magmatically derived. Some sulfide minerals, particularly those that are late stage, or distal to the main orebody, or in Proterozoic or Paleozoic rocks, have elevated Pb isotope compositions displaced toward the gross average Pb isotope composition of the local country rocks. The more radiogenic isotopic compositions argue for a contribution of Pb from those rocks at the site of ore deposition. Combining the Pb isotope data with available geochemical, isotopic, and petrologic data suggests derivation of the young porphyry copper-related plutons, most of their Pb, and other metals from a hybridized lower continental crustal source. Because of the likely involvement of subduction-related mantle-derived basaltic magma in the hybridized lower crustal source, an indiscernible mantle contribution is probable in the porphyry magmas. Clearly, in addition

Enrichment of copper and recycling of cyanide from copper-cyanide waste by solvent extraction

NASA Astrophysics Data System (ADS)

Gao, Teng-yue; Liu, Kui-ren; Han, Qing; Xu, Bin-shi

2016-11-01

The enrichment of copper from copper-cyanide wastewater by solvent extraction was investigated using a quaternary ammonium salt as an extractant. The influences of important parameters, e.g., organic-phase components, aqueous pH values, temperature, inorganic anion impurities, CN/Cu molar ratio, and stripping reagents, were examined systematically, and the optimal conditions were determined. The results indicated that copper was effectively concentrated from low-concentration solutions using Aliquat 336 and that the extraction efficiency increased linearly with increasing temperature. The aqueous pH value and concentrations of inorganic anion impurities only weakly affected the extraction process when varied in appropriate ranges. The CN/Cu molar ratio affected the extraction efficiency by changing the distribution of copper-cyanide complexes. The difference in gold leaching efficiency between using raffinate and fresh water was negligible.

Antimalarial, antimicrobial, cytotoxic, DNA interaction and SOD like activities of tetrahedral copper(II) complexes

NASA Astrophysics Data System (ADS)

Mehta, Jugal V.; Gajera, Sanjay B.; Patel, Mohan N.

2015-02-01

The mononuclear copper(II) complexes with P, O-donor ligand and different fluoroquinolones have been synthesized and characterized by elemental analysis, electronic spectra, TGA, EPR, FT-IR and LC-MS spectroscopy. An antimicrobial efficiency of the complexes has been tested against five different microorganisms in terms of minimum inhibitory concentration (MIC) and displays very good antimicrobial activity. The binding strength and binding mode of the complexes with Herring Sperm DNA (HS DNA) have been investigated by absorption titration and viscosity measurement studies. The studies suggest the classical intercalative mode of DNA binding. Gel electrophoresis assay determines the ability of the complexes to cleave the supercoiled form of pUC19 DNA. Synthesized complexes have been tested for their SOD mimic activity using nonenzymatic NBT/NADH/PMS system and found to have good antioxidant activity. All the complexes show good cytotoxic and in vitro antimalarial activities.

Binary and ternary copper(II) complexes of a new Schiff base ligand derived from 4-acetyl-5,6-diphenyl-3(2H)-pyridazinone: Synthesis, spectral, thermal, antimicrobial and antitumor studies

NASA Astrophysics Data System (ADS)

Shebl, Magdy; Adly, Omima M. I.; Abdelrhman, Ebtesam M.; El-Shetary, B. A.

2017-10-01

A new Schiff base ligand was synthesized by the reaction of 4-acetyl-5,6-diphenyl-3(2H)-pyridazinone with ethylenediamine. A series of binary copper(II) Schiff base complexes have been synthesized by using various copper(II) salts; AcO-, NO3-, ClO4-, Cl- and Br-. Ternary complexes were synthesized by using auxiliary ligands (L‧) [N,O-donor; 8-hydroxyquinoline and glycine or N,N-donor; 1,10-phenanthroline, bipyridyl and 2-aminopyridine]. The structures of the Schiff base and its complexes were characterized by elemental and thermal analyses, IR, electronic, mass, 1H NMR and ESR spectra in addition to conductivity and magnetic susceptibility measurements. The obtained complexes include neutral binuclear complexes as well as neutral and cationic mononuclear complexes according to the anion used and the experimental conditions. The ESR spin Hamiltonian parameters of some complexes were calculated and discussed. The metal complexes exhibited octahedral and square planar geometrical arrangements depending on the nature of the anion. Kinetic parameters (Ea, A, ΔH, ΔS and ΔG) of the thermal decomposition stages were evaluated using Coats-Redfern equations. The antimicrobial activity of the Schiff base and its complexes was screened against Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Salmonella typhimurium and Escherichia coli), yeast (Candida albicans) and fungus (Aspergillus fumigatus). The antitumor activity of the Schiff base and some of its Cu(II) complexes was investigated against HepG-2 cell line.

Nonlinear optical and G-Quadruplex DNA stabilization properties of novel mixed ligand copper(II) complexes and coordination polymers: Synthesis, structural characterization and computational studies

NASA Astrophysics Data System (ADS)

Rajasekhar, Bathula; Bodavarapu, Navya; Sridevi, M.; Thamizhselvi, G.; RizhaNazar, K.; Padmanaban, R.; Swu, Toka

2018-03-01

The present study reports the synthesis and evaluation of nonlinear optical property and G-Quadruplex DNA Stabilization of five novel copper(II) mixed ligand complexes. They were synthesized from copper(II) salt, 2,5- and 2,3- pyridinedicarboxylic acid, diethylenetriamine and amide based ligand (AL). The crystal structure of these complexes were determined through X-ray diffraction and supported by ESI-MAS, NMR, UV-Vis and FT-IR spectroscopic methods. Their nonlinear optical property was studied using Gaussian09 computer program. For structural optimization and nonlinear optical property, density functional theory (DFT) based B3LYP method was used with LANL2DZ basis set for metal ion and 6-31G∗ for C,H,N,O and Cl atoms. The present work reveals that pre-polarized Complex-2 showed higher β value (29.59 × 10-30e.s.u) as compared to that of neutral complex-1 (β = 0.276 × 10-30e.s.u.) which may be due to greater advantage of polarizability. Complex-2 is expected to be a potential material for optoelectronic and photonic technologies. Docking studies using AutodockVina revealed that complex-2 has higher binding energy for both G-Quadruplex DNA (-8.7 kcal/mol) and duplex DNA (-10.1 kcal/mol). It was also observed that structure plays an important role in binding efficiency.

Newer mixed ligand Schiff base complexes from aquo-N-(2‧-hydroxy acetophenone) glycinatocopper(II) as synthon: DFT, antimicrobial activity and molecular docking study

NASA Astrophysics Data System (ADS)

Pramanik, Harun A. R.; Das, Dharitri; Paul, Pradip C.; Mondal, Paritosh; Bhattacharjee, Chira R.

2014-02-01

Synthesis of a series of newer mixed ligand copper(II) complexes of aminoacid Schiff base of the type [CuL(X)] (L = N-(2‧-hydroxy acetophenone) glycinate, X = imidazole (im) 2, benzimidazole (benz) 3, pyridine (py) 4, hydrazine (hz) 5,8-hydroxyquinoline (8-hq) 6, pyrrolidine (pyrr) 7, piperidine (pip) 8, and nicotinamide (nic) 9) have been accomplished from the interaction of an aquated Schiff base complex, [CuL(H2O)]·H2O, 1 with some selected neutral nitrogen-donor ligands. The copper(II) Schiff base complex, [CuL(H2O)]·H2O, L = N-(2‧-hydroxy acetophenone) glycinate was synthesized from the reaction of glycine and 2‧ hydroxy acetophenone and copper(II) acetate. The compounds were characterised by elemental analysis, spectral, magnetic and thermal studies. The density functional theory calculations were performed using LANL2DZ and 6-311 G(d, p) basis sets with B3LYP correlation functional to ascertain the stable electronic structure, HOMO-LUMO energy gap, chemical hardness and dipole moment of the mixed ligand complexes. A distorted square planar geometry has been conjectured for the complexes. Antibacterial activities of the ligand and its metal complexes have been tested against selected gram-positive and gram-negative strains and correlated with computational docking scores.

Ylide Ligands as Building Blocks for Bioactive Group 11 Metal Complexes.

PubMed

Gimeno, M Concepción; Johnson, Alice; Marzo, Isabel

2018-05-22

The reactivity of the phosphonium salt, (cyanomethyl)triphenylphosphonium chloride, and the ylide, triphenylphosphoniumcyanomethylide, towards group eleven metal complexes is described. Mononuclear neutral gold(I) and gold(III) complexes of the type [AuX{CH(CN)PPh3}] or [AuX3{CH(CN)PPh3}], and cationic derivatives such as [AuL{CH(CN)PPh3}]X have been prepared. Surprisingly the cationic gold species could only be prepared with ligands with a large steric hindrance such as bulky NHCs or the JohnPhos phosphine, in contrast with silver and copper derivatives which have dimeric structures with coordination to the cyano group of the ylide. Bis(ylide)metal complexes have been synthesised in which a different structure is observed for gold compared to copper and silver. While gold shows mononuclear species, the silver complex presents a bidimensional polymeric structure as a result of further coordination of the silver centre to the nitrogen of the cyano group. These complexes possess two chiral centres and the gold compound is obtained as a mixture of diastereoisomers, whereas the copper and silver derivatives afford only one diastereroisomer. These compounds were screened for the in vitro cytotoxic activity against the human lung carcinoma cell line (A549). The IC50 values reveal an excellent cytotoxic activity for these metal complexes compared with cisplatin. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Binding of copper to lysozyme: Spectroscopic, isothermal titration calorimetry and molecular docking studies

NASA Astrophysics Data System (ADS)

Jing, Mingyang; Song, Wei; Liu, Rutao

2016-07-01

Although copper is essential to all living organisms, its potential toxicity to human health have aroused wide concerns. Previous studies have reported copper could alter physical properties of lysozyme. The direct binding of copper with lysozyme might induce the conformational and functional changes of lysozyme and then influence the body's resistance to bacterial attack. To better understand the potential toxicity and toxic mechanisms of copper, the interaction of copper with lysozyme was investigated by biophysical methods including multi-spectroscopic measurements, isothermal titration calorimetry (ITC), molecular docking study and enzyme activity assay. Multi-spectroscopic measurements proved that copper quenched the intrinsic fluorescence of lysozyme in a static process accompanied by complex formation and conformational changes. The ITC results indicated that the binding interaction was a spontaneous process with approximately three thermodynamical binding sites at 298 K and the hydrophobic force is the predominant driven force. The enzyme activity was obviously inhibited by the addition of copper with catalytic residues Glu 35 and Asp 52 locating at the binding sites. This study helps to elucidate the molecular mechanism of the interaction between copper and lysozyme and provides reference for toxicological studies of copper.

The effect of copper doping on martensite shear stress in porous TiNi(Mo,Fe,Cu) alloys

NASA Astrophysics Data System (ADS)

Khodorenko, V. N.; Kaftaranova, M. I.; Gunther, V. E.

2015-03-01

The properties of alloys based on porous nickel-titanium (TiNi) with copper additives have been studied. It is established that the copper doping of porous TiNi(Mo,Fe,Cu) alloys fabricated by the method of self-propagating high-temperature synthesis leads to a significant decrease in the martensite shear stress (below 30 MPa). Low values of the martensite shear stress (σmin) in copper-doped TiNi-based alloys allows medical implants of complex shapes to be manufactured for various purposes, including oral surgery. The optimum concentration of copper additives (within 3-6 at %) has been determined that ensures high performance characteristics of TiNi-based porous alloys for medical implants.

Effect of Copper Acyclovir Complexes on Herpes Simplex Virus Type 1 and Type 2 (HSV-1, HSV-2) Infection in Cultured Cells

PubMed Central

Panteva, M.; Varadinova, T.; Turel, I.

1998-01-01

We have found that when copper, zinc or cobalt is bound to a suitable ligand, the appropriate complex exhibited a significant anti-HSV effect (Varadinova et al., 1993; 1996). Recently published data by Sagripanti et al. (1997) also show that the inhibition of HSV by copper was enhanced by reducing agents and that mechanism of the inactivation is similar as for copper-mediated DNA damage (Aruoma, et al. 1991; Dizdaroglu, et al., 1991; Toyokuni and Sagripanti, 1994). Therefore it was interesting to study the efect of Cu(ll) coordination compounds with acyclovir (ACV) on the replication of HSV in cultured cells. The experiments on cytotoxicity as well as on the activity of three different Cu-ACV complexes [Cu(ACV)2Cl2(H2O)2] = (A); [Cu(ACV)2(H2O)3](NO3)2.H2O = (B) and [Cu(ACV)2(H2O)2](NO3)2] = (C) towards virus replication, with special attention on the growth of ACV-resistant strain R-100 were performed on MDBK cells. ACV was used as a reference compound. The following results were obtained: 1) Increased cell’s viability in the presence of 20-40(g/ml ACV and decreased one in the presence of Cu-ACV complexes with relative level (A) >> (B) > (C); 2) Cu-ACV complexes are more cytotoxic than the ligand - ACV and the relative level is (C)>(B)>(A); 3) The anti-HSV effect of ACV can be modulated by copper at levels depending on the specificity of the particular virus strain: (i) for the ACV sensitive strain DA (HSV-1) - ACV ((A) > (C) > (B); (ii) for the ACV sensitive strain Bja (HSV-2) (A) > ACV > (C) > (B); (iii) for strain R-100 (ACVR, TKa) - (A) > ACV > (C) > (B). This findings are consistent with previously published data and undoubtedly show that Cu-ACV complexes could be useful in the treatment of HSV infections, especially when the causative agent is a resistant to ACV mutant. PMID:18475820

Structure of complexes of nitrilo tris methylene phosphonic acid with copper, [CuN(CH{sub 2}PO{sub 3}){sub 3}(H{sub 2}O){sub 3}] and Na{sub 4}[CuN(CH{sub 2}PO{sub 3}){sub 3}]{sub 2} · 19H{sub 2}O, as bactericides and inhibitors of scaling and corrosion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Somov, N. V., E-mail: somov@phys.unn.ru; Chausov, F. F., E-mail: chaus@uni.udm.ru

2015-03-15

Nitrilotris methylene phosphonate triaqua copper and octasodium bis(nitrilotris methylene phosphonate cuprate(II)) nonadecahydrate have been synthesized and investigated. [CuN(CH{sub 2}PO{sub 3}){sub 3}(H{sub 2}O){sub 3}] is crystallized in the sp. gr. P2{sub 1}/c, Z = 4, a = 9.2506(2) Å, b = 15.9815(2) Å, c = 9.5474(2) Å, β = 113.697(2)°. The copper atom is coordinated by oxygen atoms in the configuration of elongated octahedron; the ligand (of bridge type) links neighboring copper atoms. Na{sub 8}[CuN(CH{sub 2}PO{sub 3}){sub 3}]{sub 2} · 19H{sub 2}O is crystallized in the sp. gr. P2{sub 1}/c, Z = 2, a = 11.24550(10) Å, b = 17.38980(10) Å,more » c = 13.5852(2) Å, β = 127.8120(10)°. This complex is chelating; the copper atom closes three five-membered N-C-P-O-Cu cycles with a shared Cu-N bond. Copper is coordinated in a distorted trigonal-bipyramidal configuration.« less

Raman spectroscopic studies of the interaction of oxalic acid and sodium oxalate used as corrosion inhibitors with copper

NASA Astrophysics Data System (ADS)

Jeziorowski, H.; Moser, B.

1985-09-01

The Raman spectra of the liquid-solid interface recorded in situ show the formation of a salt complex of the inhibitor molecules and the copper ions. This suggests that this chemisorbed surface species produces the protective layer.

Coordination Chemistry of Cyclic Disilylated Germylenes and Stannylenes with Group 11 Metals

PubMed Central

2014-01-01

Reactions of Et3P adducts of bissilylated germylenes and stannylenes with gold, silver, and copper cyanides led to cyanogermyl or -stannyl complexes of the respective metals. In the course of the reaction the phosphine moved to the metal, while the cyanide migrated to the low-coordinate group 14 element. The respective gold complexes were found to be monomeric, whereas the silver and copper complexes exhibited a tendency to dimerize in the solid state. Attempts to abstract the phosphine ligand with B(C6F5)3 led only to the formation of adducts with the borane coordinating to the cyanide nitrogen atom. PMID:25550678

Root Uptake Of Lipophilic Zinc-Rhamnolipid Complexes

EPA Science Inventory

This study investigated the formation and plant uptake of lipophilic metal-rhamnolipid complexes. Monorhamnosyl and dirhamnosyl rhamnolipids formed lipophilic complexes with copper (Cu), manganese (Mn), and zinc (Zn). Rhamnolipids significantly increased Zn absorption by Bra...