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1.
《Journal of Coordination Chemistry》2012,65(7):821-826
An axially elongated copper(II) complex, CuL1Cl2, has been obtained by reaction of copper(II) chloride with a 17-membered N,O-donor macrocyclic ligand (L1). In an attempt to prepare the complex from copper(II) perchlorate, crystals of L1 suitable for X-ray were obtained as its diperchlorate salt, [H2L1][ClO4]2. Further reaction of CuL1Cl2 with LiTCNQ and Et3NH(TCNQ)2 furnished the charge transfer copper(I) complexes CuL1(TCNQ)2·3H2O and CuL1(TCNQ)3, with TCNQ carrying partially reduced charge. The presence of a diamagnetic metallic centre was confirmed by EPR and magnetic measurements. 相似文献
2.
In this study, a very simple spectrophotometric method for the simultaneous determination of citric and ascorbic acid based
on the reaction of these acids with a copper(II)-ammonia complex is presented. The Cu2+-NH3 complex (with λmax = 600 nm) was decomposed by citrate ion and formed a Cu2+-citrate complex (with λmax = 740 nm). On the other hand, during the reaction of ascorbic acid with copper(II)-ammonia complex, ascorbic acid is oxidized
and the copper(II)-ammonia complex is reduced to the copper(I)-ammonia complex and the absorbance decreases to 600 nm. Although
there is a spectral overlap between the absorbance spectra of complexes Cu2+-NH3 and Cu2+-citrate, they have been simultaneously determined using an artificial neural network (ANN). The absorbances at 600 and 740
nm were used as the input layer. The ANN architectures were different for citric and ascorbic acid. The output of the citric
acid ANN architecture was used as an input node for the ascorbic acid ANN architecture. This modification improves the capability
of the ascorbic acid ANN model for the prediction of ascorbic acid concentrations. The dynamic ranges for citric and ascorbic
acid were 1.0–125.0 and 1.0–35.0 mM, respectively. Finally, the proposed method was successfully applied to the determination
of citric and ascorbic acids in vitamin C tablets and some powdered drink mixes.
The text was submitted by the authors in English. 相似文献
3.
The effect of additional Cu(II) ions on the rate of transformation of S‐(2‐oxotetrahydrofuran‐3‐yl)‐N‐(4‐methoxyphenyl)isothiouronium bromide ( 1 ) into 5‐(2‐hydroxyethyl)‐2‐[(4‐methoxyphenyl)imino]‐1,3‐thiazolidin‐4‐one ( 2 ) has been studied in aqueous buffer solutions. The reaction acceleration in acetate buffers is caused by the formation of a relatively weakly bonded complex (Kc = 600 L·mol?1) of substrate with copper(II) acetate in which the Cu(II) ion acts as a Lewis acid coordinating the carbonyl oxygen and facilitating the intramolecular attack, leading to the formation of intermediate T±. The formation of the complex of copper(II) acetate with free isothiourea in the fast preequilibrium (Kc) is followed by the rate‐limiting transformation (kCu) of this complex. At the high concentrations of the acetate anions, the reaction is retarded by the competitive reaction of these ions with copper(II) acetate to give an unreactive complex [Cu(OAc)4]2?. The influence of Cu(II) ions on the stability of reaction intermediates and the leaving group ability of the alkoxide‐leaving group compared to the Cu(II)‐uncatalyzed reaction is also discussed. 相似文献
4.
Thermochemical and kinetic equations for nonequilibrium reactions that occur at constant pressure and temperature were proposed. Thermodynamic and kinetic characteristics of copper(II) reaction with histidine (His) were obtained. The enthalpy of formation of copper(II) complex with histidine at temperatures from 298.15 to 323.15 K was determined by microcalorimetry. The standard enthalpy of formation of Cu(His)2
2
+(aq) was calculated. The enthalpy, entropy, and Gibbs energy of activation, rate constants, activation energies, preexponential factor, and reaction order were obtained on the basis of experimental and calculated data. The resulting data suggest that the title reaction readily proceeds at the indicated temperatures. The Cu(His)2Cl2·H2O complex was isolated in the solid state and characterized by IR spectroscopy and thermal analysis. 相似文献
5.
Yueyang Zhu Cun-Fang Wang Kai Yan Ke-Dong Zhao Gui-Hua Sheng Qiqige Hu 《Journal of Coordination Chemistry》2016,69(16):2493-2499
A dicyanoamide-bridged polymeric copper(I/II) complex, [CuII(sal)(bipy)CuI(dca)2]n, was prepared by reaction of 5-methylchlorosalicylaldehyde (Hsal), 2,2′-bipyridine (bipy), sodium dicyanoamide (Nadca), and copper perchlorate in methanol. The complex was characterized by elemental analyses, infrared and electronic spectroscopy, and single-crystal X-ray determination. CuII has a square pyramidal coordination, and CuI has triangular coordination. The complex showed high urease inhibitory activity with IC50 value of 0.16 ± 0.23 μM. 相似文献
6.
Kamonwad Ngamchuea Dr. Christopher Batchelor‐McAuley Prof. Dr. Richard G. Compton 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(44):15937-15944
The kinetics and mechanisms of the copper(II)‐catalyzed GSH (glutathione) oxidation are examined in the light of its biological importance and in the use of blood and/or saliva samples for GSH monitoring. The rates of the free thiol consumption were measured spectrophotometrically by reaction with DTNB (5,5′‐dithiobis‐(2‐nitrobenzoic acid)), showing that GSH is not auto‐oxidized by oxygen in the absence of a catalyst. In the presence of Cu2+, reactions with two timescales were observed. The first step (short timescale) involves the fast formation of a copper–glutathione complex by the cysteine thiol. The second step (longer timescale) is the overall oxidation of GSH to GSSG (glutathione disulfide) catalyzed by copper(II). When the initial concentrations of GSH are at least threefold in excess of Cu2+, the rate law is deduced to be ?d[thiol]/dt=k[copper–glutathione complex][O2]0.5[H2O2]?0.5. The 0.5th reaction order with respect to O2 reveals a pre‐equilibrium prior to the rate‐determining step of the GSSG formation. In contrast to [Cu2+] and [O2], the rate of the reactions decreases with increasing concentrations of GSH. This inverse relationship is proposed to be a result of the competing formation of an inactive form of the copper–glutathione complex (binding to glutamic and/or glycine moieties). 相似文献
7.
On reaction of different copper(II) salts with 3,4-bis(2-pyridylmethylthio)toluene (L) having neutral tetradentate NSSN donor set in different chemical environments, two mononuclear copper(II), one dinuclear copper(I) and one dinuclear copper(II) complexes, formulated as [CuII(L)(H2O)2](NO3)2 (1), [CuII(pic)2] (2), [CuI2(L)2](ClO4)2 (3) and [CuII2(L)2Cl2](ClO4)2 (4), respectively, were isolated in pure form [where pic = picolinate]. All the complexes were characterized by physicochemical and spectroscopic methods. The product of the reactions are dependent on the counter anion of copper(II) salts used as reactant and on the reaction medium. Complexes 1 and 4 were obtained with nitrate and perchlorate copper(II) salts, respectively. On the other hand, C–S bond cleavage was observed in the reaction of L with copper(II) chloride to form in situ picolinic acid and complex 2. Dinuclear complexes 3 and 4 were separated out when copper(II) perchlorate was allowed to react with L in methanol and in acetonitrile, respectively, under aerobic condition. The X-ray diffraction analysis of the dinuclear complex 3 shows a highly distorted tetrahedral geometry about each copper ion. Complex 4 is converted to 3 in acetonitrile in presence of catechol. The spectral study of complex 4 with calf thymus DNA is indicative of a groove binding mode interaction. 相似文献
8.
D. A. Piryazev A. S. Zhilin A. I. Smolentsev A. V. Virovets S. F. Vasilevskii L. G. Lavrenova 《Journal of Structural Chemistry》2011,52(2):376-382
Polymeric complexes of [Cu2Cl2L2]∞ copper(I) chloride (1) (L = N1,N2-bis(5-methylpyridin-2-yl)-oxalamide)) and {[Cu2(C2O4)Cl2L](L)·2H2O}∞ copper(II) chloride (2) are obtained. The complexes are studied by powder and single crystal XRD. It is found that during the reaction of L with
copper(II) chloride in the formation of complex 1 copper(II) is reduced to copper(I), while the formation of complex 2 is accompanied by the hydrolysis of the ligand. 相似文献
9.
In the previous,1 we reported the cyclopropane synthesis in which - monochloromethylcopper(1)isonitrile (2), a copper carbenoid complex, formed in the reaction of α-monochloro-carbonyl or nitrile (1) with the cu2Ol-isonitrile complex was subjected to the reaction with an electron defecient olefin. 相似文献
10.
Production of singlet molecular oxygen (1O2) in the aerobic oxidation of ascorbic acid catalyzed by copper ion was measured and characterized using [4′-(9-anthryl)-2,2′:6′,2″-terpyridine-6,6″-diyl]bis(methylenenitrilo)tetrakis(acetate)-Eu3+ (ATTA-Eu3+) as a highly sensitive and selective time-resolved luminescence probe for 1O2. The 1O2 produced in the reaction was further characterized and confirmed by (i) chemical trapping of 1O2 with 9,10-diphenylanthracene (DPA), the corresponding endoperoxide was detected by HPLC and (ii) spin trapping of 1O2 with 2,2,6,6-tetramethyl-4-piperidinol (TMP-OH), the corresponding free radical of TMP-OH oxide (TMPO) was detected by electron spin resonance (ESR) spectroscopy. The effects of deuterium oxide, sodium azide and histidine on the 1O2 signal were investigated. The mechanism investigation of 1O2 production implied that the ascorbic acid-Cu(I) complex formed in the reaction could be an important intermediate for the 1O2 production. The reaction of ascorbic acid with copper ion monitored by 1H NMR and absorption spectroscopy demonstrated the formation of a copper ion-ascorbic acid complex. Except for Cu2+ and Cu+-ascorbic acid systems, no detectable 1O2 was produced in other transition metal cation-ascorbic acid systems in the studied range. 相似文献
11.
Germund Glatz Dr. Thomas Schmalz Dr. Tobias Kraus Dipl. Ing. Frank Haarmann Prof. Dr. Günter Motz Dr. Rhett Kempe Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(14):4231-4238
A molecular approach to metal‐containing ceramics and their application as selective heterogeneous oxidation catalysts is presented. The aminopyridinato copper complex [Cu2(ApTMS)2] (ApTMSH=(4‐methylpyridin‐2‐yl)trimethylsilanylamine) reacts with poly(organosilazanes) via aminopyridine elimination, as shown for the commercially available ceramic precursor HTT 1800. The reaction was studied by 1H and 13C NMR spectroscopy. The liberation of the free, protonated ligand ApTMSH is indicative of the copper polycarbosilazane binding. Crosslinking of the copper‐modified poly(organosilazane) and subsequent pyrolysis lead to the copper‐containing ceramics. The copper is reduced to copper metal during the pyrolysis step up to 1000 °C, as observed by solid‐state 65Cu NMR spectroscopy, SEM images, and energy‐dispersive spectroscopy (EDS). Powder diffraction experiments verified the presence of crystalline copper. All Cu@SiCN ceramics show catalytic activity towards the oxidation of cycloalkanes using air as oxidant. The selectivity of the reaction increases with increasing copper content. The catalysts are recyclable. This study proves the feasibility of this molecular approach to metal‐containing SiCN precursor ceramics by using silylaminopyridinato complexes. Furthermore, the catalytic results confirm the applicability of this new class of metal‐containing ceramics as catalysts. 相似文献
12.
《Journal of Coordination Chemistry》2012,65(3):181-188
Abstract Preparation and isolation of the polynuclear copper(II) complex, {[Cu(bipy)(maleato)] · 2H2O} n , was accomplished by reaction of an aqueous solution containing sodium maleate and an ethanolic solution of Cu(NO3)2·4H2O and bipy. The crystal structure of the title complex was determined by single-crystal X-ray methods. The structure consists of one-dimensional infinite chains. The copper atom is five-coordinate and presents a square-pyramidal coordination sphere, which consists of the two imine N atoms of bipy and two terminal carboxylate O atoms of a maleate2- ligand in the basal plane with Cu-N bond distances of 2.016(3) and 1.987(3) A and Cu-O distances of 1.909(2) and 1.947(2) Å, respectively. In the apical site an O atom of the maleate2- ligand from an adjacent complex coordinates to copper (2.264(2) Å). The coordination fashion of the maleato ligand is also confirmed by the IR spectrum. 相似文献
13.
Sergei V. Voitekhovich Mikhail M. Degtyarik Alexander S. Lyakhov Ludmila S. Ivashkevich Jennifer Klose Berthold Kersting Oleg A. Ivashkevich 《无机化学与普通化学杂志》2020,646(15):1331-1335
Complex [Cu(tbt)Cl2]n (tbt = 1-tert-butyl-1H-tetrazole) was prepared by reaction of tbt with copper(II) chloride in solution. According to single-crystal X-ray analysis, this complex presents 1D coordination polymer, formed at the expense of double chlorido bridges between neighboring pentacoordinate copper(II) cations. 1-tert-Butyl-1H-tetrazole acts as monodentate ligand coordinated by CuII cations via the heteroring N4 atoms. The temperature-dependent magnetic susceptibility measurements of novel complex [Cu(tbt)Cl2]n as well as described previously 1D coordination polymer [Cu(tbt)2Cl2]n, and linear trinuclear complex [Cu3(tbt)6Br6], were carried out. Magnetic studies revealed that the copper(II) ions were weakly ferromagnetically coupled in polymeric copper(II) chloride complexes, whereas complex [Cu3(tbt)6Br6] showed antiferromagnetic coupling. 相似文献
14.
Two copper(I) complexes [Cu(Cin2bda)2]ClO4 (I) and [Cu(Ncin2bda)2]ClO4 (II) have been prepared by the reaction of the ligands N2,N2′-bis(3-phenylallylidene)biphenyl-2,2′-diamine (L1) and N2,N2′-bis[3-(2-nitrophenyl)allylidene]biphenyl-2,2′-diamine (L2) and copper(I) salt. These compounds were characterized by CHN analyses, 1H NMR, IR, and UV-Vis spectroscopy. The C=N stretching frequency in the copper(I) complexes shows a shift to a lower frequency
relative to the free ligand due to the coordination of the nitrogen atoms. The crystal and molecular structure of II was determined
by X-ray single-crystal crystallography. The coordination polyhedron about the copper(I) center in the complex is best described
as a distorted tetrahedron. A quasireversible redox behavior was observed for complexes I and II.
The article is published in the original. 相似文献
15.
一种大环化合物的晶体结构及其双核铜配合物的酪氨酸酶活性研究 总被引:2,自引:0,他引:2
A ring-contracted form macrocycle, 29,30-dioxo-3,6,9,17,20,23,29,30-octaazapentacyclo[23,3,1,1^11,15,0^2,6,0^16,20]-triacontaneocta- 1 (28),9,11 (12), 13,15(30),23,25(29),26-ene (L) was synthesized by condensation of diethyltriamine with pyridine-1-oxide-2,6-dicarboxaldehyde. A porous three-dimensional layer structure in its crystal was formed by self-assembly through hydrogen bonds and π-π interaction. Its dinuclear copper(I) complex [Cu2L(MeOH)2]-(BF4)2*2H2O and dinuclear-copper(II) complex [Cu2L(MeOH)2](ClO4)4*2H2O were obtained and could oxidize catalytically four phenolic substrates hydroquinone, 2-methyl-hydroquinone, 2,6-di-tert-butylphenol and 2,6-dimethylphenol, in a mixture of methanol and acetonitrile (V : V, 4 : 1). The copper(I) complex reacted with dioxygen to form an oxygenated species as an initial active intermediate for oxidation of the phenols. Oxidation of the substrates by the copper(II) complex produced a copper(I) complex and the oxidation products of the substrates. 相似文献
16.
Mikhailov Oleg V. Tatarintseva Tatyana B. Sopin Vladimir F. 《Transition Metal Chemistry》2000,25(1):32-36
The complex formation that occurs in gelatin-immobilized copper(II)hexacyanoferrate(II) matrices upon contact with aqueous alkaline (pH 12.0) solutions of 1,2-bis(thiocarbamoyl)hydrazine, H2NC(S)NHNHC(S)NH2 and 1-carbamoyl-2-(thiocarbamoyl)hydrazine, H2NC(O)NHNHC(S)NH2 has been studied. The reaction of each of these ligands with copper(II) is preceded by the destruction of copper(II)hexacyanoferrate(II) in an alkaline medium to form a polymeric copper(II) hydroxide, which is involved in the subsequent copper(II)–ligand complex formation. In both CuII–N ligand systems, two complex compounds are formed; the water-insoluble Cu2B2(H2O)2 dimer and a water-soluble product of tentative composition [CuB(HB)]– (H2B=ligand). 相似文献
17.
A new complex of copper(II) picrate (pic) with 1, 3‐bis(1‐allaylbenzimidazol‐2‐yl)‐2‐oxopropane (aobb), with the composition [Cu(aobb)2](pic)2, was synthesized and characterized. The crystal structure of the copper(II) complex revealed that the coordination environment around the central copper(II) atom is a distorted octahedral arrangement. Electronic absorption spectroscopy, ethidium bromide displacement experiments and viscosity measurements indicate that the ligand and the CuII complex can strongly bind to calf thymus DNA, presumably by an intercalation mechanism. Furthermore, the antioxidant activity of the CuII complex was determined by superoxide and hydroxyl radical scavenging method in vitro, which indicate that the CuII complex has the activity to suppress OH · and O2 · –. 相似文献
18.
Robert D. Braun 《Analytica chimica acta》1978,99(2):325-331
Polarographic, cyclic voltammetric and controlled-potential coulometric studies of copper(II) nitrate and perchlorate in dimethylformamide are reported. Copper(II) in copper(II) perchlorate solutions is directly reduced in a 2e step to copper metal at platinum electrodes and to a copper amalgam at mercury electrodes. Copper(II) in the presence of nitrate forms a complex of composition Cu(N03)2 in DMF; the dissociation constant, measured polarographically, is 9 × lO-5. The copper(II) nitrate complex is electrochemically reduced in two steps consisting of a reversible dissociation of the complex followed by direct reduction of copper(II) ion to copper(0). The diffusion coefficients of copper(II) ion and the copper(II) nitrate complex are 4.91 × lO-6 cm2 s-1 and 4.33 × 10-6 cm2 s-1, respectively. 相似文献
19.
A study was made of the reactions between chlorotris(methyldiphenylphosphine)copper(I) and several hydroborates containing a boron-oxygen bond. The new complex ((acetoxy)trihydroborato)tris(methyldiphenylphosphine)copper(I) (Ph2MeP)3CuH3B(O2CCH3) was isolated and characterized by analysis, IR, and NMR data. Analogous reaction conditions using HB(OR)3? anions did not give a BH containing product nor did several other anions of the general type HBR3?. The ability of the hydroborate to complex is related to the Lewis acidity of the respective borane attached to H?. 相似文献
20.
Craig A. Bell Paul V. Bernhardt Prof. Lawrence R. Gahan Prof. Manuel Martínez Prof. Michael J. Monteiro Prof. Carlos Rodríguez Clint A. Sharrad Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(10):3166-3175
The potentially hexadentate mixed‐donor cage ligand 1‐methyl‐8‐amino‐3,13,16‐trithia‐6,10,19‐triazabicyclo[6.6.6]eicosane (AMME‐N3S3sar; sar=sarcophagine) displays variable coordination modes in a complex with copper(II). In the absence of coordinating anions, the ligand adopts a conventional hexadentate N3S3 binding mode in the complex [Cu(AMME‐N3S3sar)](ClO4)2 that is typical of cage ligands. This structure was determined by X‐ray crystallography and solution spectroscopy (EPR and NIR UV/Vis). However, in the presence of bromide ions in DMSO, clean conversion to a five‐coordinate bromido complex [Cu(AMME‐N3S3sar)Br]+ is observed that features a novel tetradentate (N2S2)‐coordinated form of the cage ligand. This copper(II) complex has also been characterized by X‐ray crystallography and solution spectroscopy. The mechanism of the reversible interconversion between the six‐ and five‐coordinated copper(II) complexes has been studied and the reaction has been resolved into two steps; the rate of the first is linearly dependent on bromide ion concentration and the second is bromide independent. Electrochemistry of both [Cu(AMME‐N3S3sar)]2+ and [Cu(AMME‐N3S3sar)Br]+ in DMSO shows that upon reduction to the monovalent state, they share a common five‐coordinated form in which the ligand is bound to copper in a tetradentate form exclusively, regardless of whether a six‐ or five‐coordinated copper(II) complex is the precursor. 相似文献