- Synthesis and characterisation of zinc gallyl complexes: First structural elucidations of Zn-Ga bonds
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Reactions of the anionic gallium(i) heterocycle, [:Ga{[N(Ar)C(H)] 2}]- (Ar = C6H3Pri 2-2,6), with two N,N-chelated zinc chloride complexes have yielded the compounds, [{Pri2
- Jones, Cameron,Rose, Richard P.,Stasch, Andreas
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- Synthesis, characterization and photoelectrochemical properties of poly(3,4-dioctyloxythiophene)-CdS hybrid electrodes
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CdS-poly(3,4-dioctyloxythiophene) (CdS-PDOT) hybrid electrode has been prepared by electrosynthesis of PDOT on Au substrate followed by electrodeposition of Cd and its chemical transformation into CdS. The polymer and semiconductor obtained by this method form hemispherical structures dispersed on the substrate. The synthesized composites were characterized by UV-vis absorption spectra and energy dispersive X-ray spectra (EDS). The AFM images of the electrodes covered with different amounts of each component were correlated with photoactivity of the hybrid electrodes. Photoresponses of Au/PDOT-CdS electrodes under illumination in aqueous solution of Na2S were also compared with those of CdS without polymer. Enhancement of the photocurrent achieved for some polymer-to-semiconductor ratio is discussed in terms of the hybrid electrode morphology and hole-mediating properties of PDOT. The power conversion efficiency of the device based on CdS-PDOT hybrid electrode was determined from photocurrent-potential behavior of two electrode system, Au/CdS-PDOT/0.1 M Na2S/Pt with a variable resistance in series in the external circuit.
- Refczynska, Monika,Mieczkowski, Józef,Skompska, Magdalena
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- Synthesis of cadmium complex sulfides nanoparticles by thermal decomposition
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The paper presents the conditions of synthesis and results in the characterization (chemical analysis, thermal analysis, kinetic of decomposition) for two complex compounds of cadmium: [Cd(S2O 3)phen]×H2O and [Cd(S2/
- Dumbrava,Ciupina,Jurca,Prodan,Segal,Brezeanu
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- Synthesis and thermal analysis of cadmium complexes of imidazole and its derivatives
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Mixed complexes of the type: Cd(Sal)(HIm)2, Cd(Sal)(HIm)4·H2O, Cd(Sal)(4-MHIm)4, Cd(Im)2(HIm) and Cd(Salox)(4-MHIm)2 (where Sal = OC6H4COO2-, Salox = OCsub
- Olczak-Kobza
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- Electrodeposition of cadmium from a sulfate electrolyte in the presence of a fixative
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Electrodeposition of cadmium from a sulfate electrolyte containing CdSO4 · 8/3H2O, H2SO4, and a fixative was studied.
- Medvedev,Makrushin
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- Synthesis, structural characterization and thermal analysis of a high nitrogen-contented cadmium (II) coordination polymer based on 1,5-diaminotetrazole
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A high nitrogen-contented cadmium (II) coordination polymer [Cd(DAT) 2(N3)2]n (DAT = 1,5- diaminotetrazole) has been synthesized and characterized by elemental analysis and FT-IR spectrum. The crystal structure was determined by using single crystal X-ray diffraction analysis with monoclinic cell: P21/n space group. Each Cd(II) cation is coordinated by two trans 1,5-diaminotetrazole ligands and four trans μ-1, 3 azido bridged ligands to form an octahedral configuration. The molecule structure is novel in that two zigzag chains linked by azido ligands which are vertical to each other and thus 2D layer networks are formed. The weak hydrogen-bonds between different layers assemble the complex to 3D supramolecular structure. Under nitrogen atmosphere with a heating rate of 10 °C/min, the DSC plot of the complex shows one endothermic process and three successive exothermic processes from 50 °C to 600 °C, and the final decomposed residue at 600 °C is Cd and few condensed products.
- Tang, Zhan,Zhang, Jian-Guo,Liu, Zhen-Hua,Zhang, Tong-Lai,Yang, Li,Qiao, Xiao-Jing
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- Recovery of cadmium and change in properties of a fibrous carbon electrode in electrolytic processing of ammonia washing solutions formed in cadmium plating
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The possibility of recovering cadmium deposited on fibrous carbon electrodes from ammonium washing solutions formed in cadmium plating via operation of a short-circuited electrochemical system or anodic dissolution was examined. A polarization study of electrode processes that occur on a renewable graphite microelectrode in ammonium solutions of varied composition was carried out. The change in the properties of fibrous carbon electrodes in their cyclic use in electrodeposition-recovery of cadmium and the possibility of their repeated use were analyzed.
- Varentsova,Varentsov
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- Radiation Electrochemistry of the Colloidal Cadmium Microelectrode. Catalysis of Hydrogen Formation by Organic Free Radicals
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Cadmium sols with a mean particle size of 11 nm or less were obtained in the radiolytic reduction of Cd2+ ions in the presence of 1E-4 - 1E-3 base-M sodium polyvinyl sulfate.These sols which contained small concentrations of residual Cd2+ were found to catalyze the formation of hydrogen by 1-hydroxy-1-methylethyl radicals, (CH3)2COH, as efficiently as the sols of the previously studied noble metals.The organic radicals transfer electrons to the colloidal particles at a practically diffusion-controlled rate.The cathodically charged colloidal particles first reduce and deposit residual cadmium ions and then store excess electrons.Both the stored electrons and the deposited cadmium atoms are able to produce H2 from water.The reduction of water by deposited cadmium atoms is explained by a two-step mechanism: (1) dissolution of an atom as Cd2+ to leave negative charges on the colloidal particle and (2) transfer of these charges to water.The mechanism of catalysis is also described in terms of an equivalent electrical circuit, in which the colloidal microelectrode appears as a capacitance for the storage of reduction equivalents.A 3E-4 M cadmium solution (containing ca. 3E-5 M residual Cd2+ ions) was found to have a capacity of 0.98 F/L for the storage of excess electrons.
- Henglein, A.,Lilie, J.
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- Simple thermal evaporation route to synthesize Zn and Cd metal nanowires
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Metallic Zn and Cd nanowires were produced by a simple thermal evaporation process using their respective sulfide powders as the precursors. Metallic nanowires were found to be of pure phase without the presence of any sulfide or oxide phases. These nanowires were single crystalline. Diameters of both the Zn and Cd nanowires varied within 100-150 nm and their lengths were approximately a few micrometers. Crystal structure, phase and chemical purity of the nanowires were characterized by XRD and EDAX. The morphology and crystallinity of the products were revealed by SEM and TEM studies.
- Kar, Soumitra,Ghoshal, Tandra,Chaudhuri, Subhadra
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- Synthesis, structural characterization, and spectroscopy of the cadmium-cadmium bonded molecular species Ar′CdCdAr′ (Ar′ = C6H3-2,6-(C6H3-2,6-Pr i2)2)
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The synthesis and first structural characterization of a cadmium-cadmium bonded molecular compound Ar-CdCdAr- (Ar- = C6H3-2,6-(C6H3-2,6-Pri2)2) are reported. The existence of the Cd-Cd bond was established by 113Cd NMR spectroscopy and X-ray diffraction (Cd-Cd = 2.6257(5) A). Like its group 12 analogue Ar-ZnZnAr-, DFT calculations showed that Ar-CdCdAr- had significant p-character in the Cd-Cd σ-bonding HOMO. Copyright
- Zhu, Zhongliang,Fischer, Roland C.,Fettinger, James C.,Rivard, Eric,Brynda, Marcin,Power, Philip P.
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- Nucleation and growth in electrodeposition of metals on n-Si(111)
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Initial stages of electrodeposition of Tl, Cd and Cu on n-Si(111) from sulfate electrolyte solutions are studied using cyclic voltammetry and chronoamperometry. Capacitance measurements in metal ion free solutions were used to determine the flat band potential of n-Si. Results show that the relative position of the metal equilibrium potential with respect to the substrate flat band potential influences significantly nucleation and growth kinetics. Within appropriate potential ranges the initial deposition kinetics corresponds to a model including progressive nucleation and diffusion controlled cluster growth. Nucleation rate and the number of atoms in the critical nucleus are determined from the analysis of current transients at different overpotentials. Results are compared with data obtained previously for electrochemical nucleation of these metals on other semiconductors and foreign metal substrates.
- Krumm,Guel,Schmitz,Staikov
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- ∞1[M(μ-O2C-C6H 4-CO2)(NH3)2] (M = Cu, Cd; O 2C-C6H4-CO2 = benzene-1,4- dicarboxylate, terephthalate): ID coordination polymers with strong inter-chain hydrogen bonding
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Compounds ∞1[M(μ-O2C-C 6H4-CO2)(NH3)2] crystallize as straight- (M = Cu) and kinked-chain (M = Cd) coordination polymers through the bridging action of the bis-mono (Cu) and bisbidentate (Cd) benzene-1,4-dicarboxylate (terephthalate) ligand. N-H...O hydrogen bonding connects the chains to a three-dimensional supramolecular network. Thermogravimetry shows the compounds to be stable up to 255°C (M = Cu) and 70°C (M = Cd) where decomposition starts with the loss of one ammin ligand. ∞1[(Cd(μ-O2C-C6H 4-CO2)(NH3)2] exhibits a luminescence with λem,max = 392 nm (λex = 240 nm) on the same order of magnitude as Na2(O2C-C 6H4-CO2).
- Paul, Barbara,Zimmermann, Boris,Fromm, Katharina M.,Janiak, Christoph
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- Study of cadmium electrochemical deposition in sulfate medium
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The cadmium electrochemical deposition process from sulfate medium was studied by means of different electrochemical techniques in both stationary and nonstationary diffusion regimes. The kinetics of the electrochemical reduction of cadmium on solid cadmium electrodes was examined and the kinetic parameters are presented, as well as the diffusion coefficient derived from the different techniques. Temperature has an important effect on the cadmium reduction kinetics, and the activation energy of the process was evaluated. The electrochemical deposition of cadmium is a complex process due to the coexistence of adsorption and nucleation processes; the adsorbed electroactive species appears to be Cd+2, and we propose a mechanism for cadmium electrodeposition on solid cadmium electrodes.
- Montiel,Solorza,Sanchez
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- ENHANCED MASS TRANSPORT IN ELECTROGALVANIZING SYSTEMS BY HYDROGEN EVOLUTION.
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The effect of hydrogen evolution on mass transport during electrogalvanizing was evaluated for a vertical electrode by using a electrochemical tracer. The potentiodynamically measured limiting current of a petroleum tracer was compared with those obtained by the codeposition method at various current densities. The effects of pH on the hydrogen evolution and the mass transfer rate during electrogalvanizing were also determined. The Sherwood number was calculated and compared with that predicted by natural convection. It has been found that the mass transport was mainly enhanced by natural convection at current densities less than 25 mA cm** minus **2 and by simultaneous hydrogen evolution at relatively higher current densities.
- Chen,O'Keefe
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- Thermal decomposition of cadmium succinate dihydrate
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Thermal decomposition of cadmium succinate dihydrate, CdC4H 4O4?2H2O, was studied in dynamic helium and air atmospheres by means of simultaneous TG, DTA and MS analysis. It was found that dehydration of CdC
- Ma?ecka, Barbara,??cz, Agnieszka
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- Kinetics and mechanism of free-surface vaporization of zinc, cadmium and mercury oxides analyzed by the third-law method
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On the basis of critical comparison of experimental and theoretical values of the E parameter and investigation of the retardation effect of oxygen on the evaporation rate of ZnO, CdO and HgO, it was concluded that the dissociative evaporation of ZnO and HgO proceeds with releasing of atomic oxygen (O) as a primary product of decomposition. By contrast, the mechanism of dissociative evaporation of CdO corresponds to the equilibrium reaction with releasing of molecular oxygen (O2) as a primary product of decomposition. As was shown, this difference in mechanisms is not related with interatomic O-O distances in these oxides. From the analysis of crystal structure for 12 different oxides, which evaporate with releasing of atomic oxygen, and for 13 compounds, which evaporate with releasing of molecular oxygen, it was revealed that the first mechanism is observed for all oxides with the cubic crystal structure. It was proposed that a decisive role in this difference belongs to a local symmetry in the position of O atoms.
- L'vov, Boris V.,Ugolkov, Valery L.,Grekov, Fedor F.
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- A new binuclear Cd(II)-containing ionic liquid: Preparation and electrocatalytic activities
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The present work reports on the synthesis, characterization and performance of a new metal-containing ionic liquid [(C10H21)2-bim]2[Cd2Cl6] (bim = benzimidazole) as an electrocatalyst of hy
- Zhuang, RuiRui,Jian, FangFang,Wang, KeFei
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- Oscillations and spatio-temporal structures during electrodeposition of AgCd alloys
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During electrodeposition of cadmium both potentiostatic and galvanostatic oscillations are registered. Experiments under different hydrodynamic conditions show the possibility of formation/destruction of passive layers on the electrode surface, which besides the hydrogen evolution under limiting current density conditions could be an additional promoter of the oscillation behavior of the system. The duration of the observed galvanostatic potential oscillations decreases with increased current density, due to massive hydrogen evolution. XPS investigations confirm the existence of passive films at potentials corresponding to the onset of oscillations. Potential oscillations are observed again during electrodeposition Ag-Cd alloys at high current densities. They appear when the cadmium content in the deposits is more than 45 wt.% and they have possibly the same origin as the oscillations during cadmium electrodeposition. The period and regularity of the oscillations depend on the current density, respectively on the cadmium content. At high cadmium content during alloy deposition, the formation of periodical structures consisting of different phases of the alloy is registered. The cadmium content of the different morphological areas of the patterns is almost identical. The XRD spectra of the obtained structured coatings suggest the existence of two textured phases, with a very strong preferred orientations of the crystallites in the direction 〈1 0 1〉 for the pure cadmium phase.
- Dobrovolska,López-Sauri,Veleva,Krastev
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- Fabrication of metal cadmium nanowires by an assistant thermal decomposition method
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Using a simple assistant thermal decomposition method, metal cadmium nanowires were large-scale fabricated from CdS powders in an argon atmosphere. Investigation results demonstrate that the Cd nanowires have lengths of several microns and diameter of about 70-150 nm. Copyright
- Zhao, Jian-Wei,Ye, Chang-Hui,Fang, Xiao-Sheng,Yan, Peng,Zhang, Li-De
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- Thermal stability and degradation of Co(II), Cd(II), and Zn(II) complexes with N-benzyloxycarbonylglycinato ligand
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Thermal behavior of Co(II), Cd(II), and Zn(II) complexes with N-benzyloxycarbonylglycinato ligand was investigated using the results of TG, DSC and DTG analysis obtained at different heating rates (2.5 to 30 °C min-1), from room temperature to about 900 °C. Mechanisms of complex degradation, as well as enthalpies of the degradation processes were determined. It is shown that thermal stability of investigated complexes correlates with their crystal structures, especially with the presence of crystallization and coordinated water molecules. The values of dehydration enthalpies are discussed and correlated with composition of the complexes. Kissinger's, Ozawa's, and Friedman's isoconversion methods were used for the determination of kinetic parameters: the pre-exponential factor A and the apparent activation energy E a. For all three complexes and all steps of degradation, the values of kinetics parameters obtained by Kissinger's and Ozawa's methods are in good agreement. The results obtained by Friedman's method showed that some decomposition steps are simple and some others are complex ones.
- Sumar-Ristovic, Maja T.,Minic, Dragica M.,Poleti, Dejan,Miodragovic, Zoran,Miodragovic, Denana,Andelkovic, Katarina K.
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- Metal azelate coordination polymers containing a kinked dipyridyl tether: CdSO4 topology and "ligand vacancy" primitive cubic three-dimensional networks
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Hydrothermal self-assembly has generated three coordination polymers incorporating the kinked hydrogen-bonding capable tethering ligand 4,4′-dipyridylamine (dpa) and the long flexible aliphatic dicarboxylate azelate dianion (-O2C(CH
- Shyu, Eric,Krishnan, Subhashree Mallika,Supkowski, Ronald M.,LaDuca, Robert L.
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- Underpotential deposition of Cd on Ag(1 1 1): An in situ STM study
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The kinetics and mechanism of Cd underpotential deposition (UPD) and involved surface alloy formation processes in the system Ag(1 1 1)/Cd 2+, SO42-, are studied by means of combined electrochemical measurements and in situ scanning tunneling microscopy (STM). The results show that the UPD process starts with a formation of an expanded (diluted) adlayer with a superlattice structure Ag(1 1 1)-(3×19)R23.4°. In the underpotential range 50 mV a condensed close packed Cd monolayer via a first order phase transition. At long polarization times the condensed monolayer undergoes structural changes involving place exchange processes between Cd atoms and surface Ag atoms. A formation of a second Cd monolayer and a significant Ag-Cd surface alloying take place at lower underpotentials (ΔE a recently proposed diffusion model including a relatively fast initial formation of a very thin surface alloy film and a subsequent slow alloy growth controlled by solid state diffusion. The anodic dealloying results in an appearance of monatomically deep pits, which disappear quickly at relatively high underpotentials (ΔE > 550 mV) indicating a high mobility of surface Ag atoms.
- García,Salinas,Staikov
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- ON THE MECHANISM OF GROWTH OF CdTe BY ORGANOMETALLIC VAPOR-PHASE EPITAXY.
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In this paper are presented some experimental results to explain mechanisms involved in the growth of CdTe by organometallic vapor-phase epitaxy (OMVPE). A pyrolysis study of dimethylcadmium (DMCd) was conducted in an OMVPE reactor, in the temperature range 230 degree -400 degree C. It was found that dimethylcadmium decomposes above approximately 230 degree C and the reaction is heterogeneous from 230 degree to 370 degree C. CdTe growth was also studied over a range of temperature from 300 degree to 375 degree C and for various reactor parameters. In all cases, the CdTe deposition rate was found to be closely related to the decomposition of dimethylcadmium.
- Bhat,Taskar,Ghandhi
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- Precursor synthesis and magnetic properties of Cd1?xFexO (0 ? x ? 0.07)
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The polycrystalline solid solutions Cd1 – xFexO (0 ? x ? 0.07) possessing ferromagnetic properties at 5 K and room temperature have been synthesized by a precursor method using the formate Cd1 – xFex(HCOO)2 ·2H2O.
- Krasil'nikov, Vladimir N.,Dyachkova, Tatyana V.,Tyutyunnik, Alexander P.,Gyrdasova, Olga I.,Perevozchikova, Yuliya A.,Marchenkov, Vyacheslav V.,Weber, Harald W.
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- Kinetics of the Reduction of Cadmium Sulfate by Thiourea Dioxide in an Aqueous Ammonia Solution upon the Metallization of Carbon Fiber
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The kinetics of the decomposition of thiourea dioxide and the reduction of cadmium cations by thiourea dioxide in an aqueous ammonia solution are studied. The kinetic parameters of these reactions are calculated using experimental data, allowing us to adj
- Polenov, Yu. V.,Egorova,Shestakov
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- Underpotential deposition of cadmium adatoms on Te and CdTe
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Underpotential deposition (UPD) of Cd adatoms onto the surface of Te and CdTe films in Cd2+-containing solutions has been studied using electrochemical methods and AFM. The electrochemical deposition of Cd adatoms on Te and CdTe begins at potentials 400 mV more positive than the reversible potential of Cd2+/Cd couple and proceeds irreversibly. A strong chemical interaction of Cd adatoms with the surface Te atoms is the driving force of the UPD process. The deposition of Cd adatoms on the tellurium surface is accompanied by their stepwise interaction with tellurium to give CdTe nanophase.
- Osipovich,Poznyak
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- Group 2 and 12 metal gallyl complexes containing unsupported Ga-M covalent bonds (M = Mg, Ca, Sr, Ba, Zn, Cd)
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Reactions of the anionic gallium(I) heterocycle [:Ga(DAB)]- (DAB = {N(Dip)C(H)}2, Dip = C6H3Pri 2-2,6) with several group 2 and 12 metal halide complexes are reported. Treatment of in situ
- Bonello, Owen,Jones, Cameron,Stasch, Andreas,Woodul, William D.
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- Multipulse electrochemical/chemical synthesis of CdS/S core/shell nanocrystals exhibiting ultranarrow photoluminescence emission lines
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Ensembles of sulfur capped, cadmium sulfide nanocrystals (CdS/S NCs) which exhibit photoluminescence (PL) emission line widths of 15-35 meV at 20 K have been obtained. These CdS/S NCs were synthesized using a new variant of the electrochemical/chemical (E/C) method: Cadmium (Cd°) NCs were first electrodeposited from an aqueous Cd2+ plating solution using a train of 8-10 ms plating pulses separated by ≈1.0 s mixing segments at the open circuit potential. These Cd° nanoparticles were then oxidized to Cd-(OH)2, and CdS/S NCs were obtained by exposure of Cd(OH)2 nanoparticles to H2S at 300°C. Ensembles of 200 000-400 000 CdS/S NCs prepared using this multipulse technique exhibited PL emission lines narrower than 35 meV. CdS/S NCs were also synthesized using the same E/C method except that a single Cd° plating pulse was employed, and these CdS/S NCs exhibited PL emission line widths of 125-180 meV. TEM analysis of Cd(OH)2 precursor particles confirms that the narrower lines obtained using multipulse Cd° electrodeposition result from improved size monodispersity of the CdS core, which is attributed to the diffusional decoupling of Cd° nanoparticles during growth.
- Gorer,Penner
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- Template-free synthesis of single-crystalline cadmium nanotubes
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By pyrolysis of CdS powder in inert gas, single-crystalline cadmium nanotubes growing in the form of a heap, were produced for the first time in high yield.
- Hu, Pingan,Liu, Yunqi,Fu, Lei,Cao, Lingchao,Zhu, Daoben
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- METALLAVIOLENES. AN ESR STUDY
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The preparation and ESR-spectroscopic characterization of radical complexes cation radical with L=4,4'-bipyridine is described, where MRn=BePh, MgPh, ZnPh, -BEt3, GaMe2, InMe2 and SiMe3.While the bis(trimethylsilyl) derivative could be obtained via one-electron oxidation of the corresponding 4,4'-(1H, 1'H)-bipyridinylidene, the other complexes were prepared by the reaction of 4,4'-bipyridine with potassium and the organometal MRn+1 or the halide XMRn in THF.Use of organo-cadmium or -thallium compounds in such a procedure leads to deposition of the metals.The Grignard reagents MgPh2 and BrMgPh reduce 4,4'-bipyridine in an electron transfer process to yield an unsymmetrical complex.The new organometallic 4,4'-bipyridinium ( violene ) radical complexes can be incorporated into a series of related radicals which exhibits the sensitivity of the unpaired electron distribution towards metal coordination.
- Kaim, Wolfgang
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- Precursor synthesis and magnetic properties of Cd1-xFexO (0?≤?x?≤?0.07) polycrystalline solid solutions
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Polycrystalline solid solutions Cd1-xFexO (0 1-xFex(HCOO)2·2H2O as a precursor. For the production of Cd1-xFexO, the precursor was annealed in air at a maximal temperature of 400 °C. At x ≥ 0.075, an impurity CdFe2O4 ferrite phase with cubic spinel structure was detected in the samples. The examination of the magnetic properties of Cd1-xFexO at 5 and 300 K revealed that they are ferromagnets, whose magnetization increases with the concentration of iron both at low and room temperature reaching the maximal values in samples with х = 0.07. In order to determine the degree of oxidation and the spin state of iron atoms, the main interatomic interactions giving rise to ferromagnetism as well as to estimate the Curie temperatures, we also performed first-principle calculations of the electronic band structure. They showed the existence of chemical bonding between adjacent iron atoms leading to the appearance of ferromagnetism by direct exchange. The value of the Curie temperature calculated by the mean field method on the basis of the first-principle calculations is 507 K, which is in reasonable agreement with the experimental value of 560 K.
- Krasilnikov,Zhukov,Gyrdasova,Dyachkova,Tyutyunnik,Perevozchikova, Yu.А.,Weber,Zaleski,Marchenkov
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- Preparation, characterization and catalytic behavior of CdFe 2O4 and Cd nanocrystals on AP, HTPB and composite solid propellants, Part: 79
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CdFe2O4 and Cd nanocrystals were synthesized by wet chemical and hydrazine reduction methods, respectively. These nanocrystals were characterized by XRD and TEM. Their catalytic activity was investigated on the thermal decomposition
- Singh,Kapoor,Dubey, Reena,Srivastava, Pratibha
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- Determination of thermodynamic stability of CdMoO4 by knudsen effusion vapor pressure measurement method
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Thermodynamic stability of CdMoO4 was determined by measuring the vapor pressures of Cd and MoO3 bearing gaseous species. Th vaporization reaction could be described as CdMoO4(s)+MoO 2(s) =Cd(g)+2/n(MoO3/s
- Mishra,Bharadwaj,Das
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- Cadmium electroextraction from alkali oxide melts
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A method is proposed for cadmium electroextraction from alkali oxide melts, suitable for CdO-containing waste processing. A bench-top electrolyzer design is described, and the process parameters are optimized.
- Barbin,Kazantsev,Vatolin
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- Synthesis, spectral characterization, density functional theory studies, and biological screening of some transition metal complexes of a novel hydrazide–hydrazone ligand of isonicotinic acid
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Novel Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II) complexes (1–7) of hydrazide–hydrazone ligand (H2L) derived from the condensation of isonicotinic acid hydrazide with (Z)-N′-(2-nitrobenzylidene)-3-oxobutanehydrazide have been prepared. The ligand and its chelates were characterized based on elemental analysis, spectral, thermal analysis, molar conductance, and magnetic moment measurements. Besides, density functional theory (DFT) computations have been conducted to study structures and energetics of the ligand and its complexes. The IR spectra showed that the ligand was chelated with the metal ion in a monobasic tridentate manner using ONO donors in all complexes except Zn(II) complex (5) where the ligand binds with Zn(II) ion as a dibasic tridentate utilizing ONO donors. The magnetic moment and electronic spectral data revealed octahedral and square pyramidal geometries for complexes (1, 7) and (2, 4, 5), respectively, whereas a square planar geometry was suggested for 3. DFT studies show that the Cd(II) center reveals interesting structural deviations from regular octahedral geometry in the resulting hexa-coordinated complex [Cd(H2L)2].2H2O (6) assumes a trigonal prismatic (TP) structure for this complex. The antibacterial and antifungal activities of the ligand and its complexes have been investigated with different bacterial and fungal strains. The data revealed that Hg(II) complex (7) demonstrated a very good antibacterial and antifungal activity than others. Highlights: A new hydrazide–hydrazone ligand of isonicotinic acid was synthesized. Seven mononuclear Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II) complexes of the new ligand were prepared and characterized by different tools. DFT studies have been carried out to study the structure of the ligand and its complexes. Antimicrobial activities of the ligand and its complexes were studied against a variety of bacterial and fungal strains by using disk diffusion method and results were compared with standard drugs.
- El-Nahas, Ahmed M.,Kashar, Tahani I.,Tolan, Dina A.,Yoshizawa, Kazunari
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- Synthesis, dft calculations, antiproliferative, bactericidal activity and molecular docking of novel mixed-ligand salen/8-hydroxyquinoline metal complexes
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Despite the common use of salens and hydroxyquinolines as therapeutic and bioactive agents, their metal complexes are still under development. Here, we report the synthesis of novel mixed-ligand metal complexes (MSQ) comprising salen (S), derived from (2,2′-{1,2-ethanediylbis [nitrilo(E) methylylidene]}diphenol, and 8-hydroxyquinoline (Q) with Co(II), Ni(II), Cd(II), Al(III), and La(III). The structures and properties of these MSQ metal complexes were investigated using molar conductivity, melting point, FTIR,1H NMR,13C NMR, UV–VIS, mass spectra, and thermal analysis. Quantum calculation, analytical, and experimental measurements seem to suggest the proposed structure of the compounds and its uncommon monobasic tridentate binding mode of salen via phenolic oxygen, azomethine group, and the NH group. The general molecular formula of MSQ metal complexes is [M(S)(Q)(H2O)] for M (II) = Co, Ni, and Cd or [M(S)(Q)(Cl)] and [M(S)(Q)(H2O)]Cl for M(III) = La and Al, respectively. Importantly, all prepared metal complexes were evaluated for their antimicrobial and anticancer activities. The metal complexes exhibited high cytotoxic potency against human breast cancer (MDA-MB231) and liver cancer (Hep-G2) cell lines. Among all MSQ metal complexes, CoSQ and LaSQ produced IC50 values (1.49 and 1.95 μM, respectively) that were comparable to that of cisplatin (1.55 μM) against Hep-G2 cells, whereas CdSQ and LaSQ had best potency against MDA-MB231 with IC50 values of 1.95 and 1.43 μM, respectively. Furthermore, the metal complexes exhibited significant antimicrobial activities against a wide spectrum of both Gram-positive and-negative bacterial and fungal strains. The antibacterial and antifungal efficacies for the MSQ metal complexes, the free S and Q ligands, and the standard drugs gentamycin and ketoconazole decreased in the order AlSQ > LaSQ > CdSQ > gentamycin > NiSQ > CoSQ > Q > S for antibacterial activity, and for antifungal activity followed the trend of LaSQ > AlSQ > CdSQ > ketoconazole > NiSQ > CoSQ > Q > S. Molecular docking studies were performed to investigate the binding of the synthesized compounds with breast cancer oxidoreductase (PDB ID: 3HB5). According to the data obtained, the most probable coordination geometry is octahedral for all the metal complexes. The molecular and electronic structures of the metal complexes were optimized theoretically, and their quantum chemical parameters were calculated. PXRD results for the Cd(II) and La(III) metal complexes indicated that they were crystalline in nature.
- Abdalla, Ehab M.,Abdel Rahman, Laila H.,Al-Farhan, Badriah Saad,Basha, Maram T.,El-Ezz, Doaa Abou,El-Saghier, Ahmed M. M.,Marzouk, Adel A.,Shehata, Mohamed R.
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- Synthesis, Structure, DFT, and Biological Activity of Metal Complexes of Norfloxacin and Metformin Mixed Ligand
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Abstract: A new series of mixed ligand metal complexes has been synthesized by the reaction of Co(II), Ni(II), Cu(II), Zr(IV), Pd(II), and Cd(II) with norfloxacin (NOR) and metformin hydrochloride (MF) in 1 : 1 : 1 molar ratio. The complexes have been characterized by FT-IR, UV-Vis, and 1H NMR spectra, TG/DTG and elemental analysis, molar conductance, and magnetic susceptibility data. According to FT-IR, NOR chelates with metal ions as a bidentate ligand via one oxygen of the carboxylate group and pyridone oxygen, and MF chelates with metal ions via two imine groups. Complexes have been identified as electrolytes. Electronic and magnetic data have indicated the octahedral structure for all complexes except square planar Pd(II) complex. Antibacterial and antifungal activities of the compounds have been tested against several species, and have indicated higher inhibition against micro-organisms for the metal complexes than the mixed ligands.
- Abbass, L. M.,El-Shwiniy, W. H.,El-Telbany, M.,Sadeek, S. A.,Zordok, W. A.
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p. 1774 - 1782
(2021/11/01)
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- Anti-hepatocellular carcinoma, antioxidant, anti-inflammation and antimicrobial investigation of some novel first and second transition metal complexes
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New coordination compounds of some selected metal ions from the first and second transition metals series with a Schiff base were synthesized and characterized. The Schiff base is derived from 4-Aminoantipyrine and 3-(hydroxyimino) butan-2-one. The compounds were characterized by different analysis tools like; elemental analysis, mass spectra, Fourier transform infrared (FTIR) as well as electronic spectra, magnetic measurements, molar conductance and thermal analysis technique. All complexes were formed with 1:1 (metal: ligand) stoichiometry except Mn (II) where 1:2 (Mn: ligand) is formed. Schiff base ligand interacted as a tridentate ligand by using the nitrogen atoms of the imine and the oximato groups and the carbonyl oxygen atom as donor groups with all studied metal ions except copper (II) and manganese (II) where the carbonyl oxygen is not shared in the coordination. These complexes show various physicochemical properties. X-ray powder diffraction shows different crystal systems; Cd (II) complex: hexagonal, Cu (II) complex: orthorhombic; and [Ni (II), Mn (II), Rh (III) & Pd (II)] complexes: monoclinic. All compounds showed potent cytotoxicity against the growth of human liver cancer cell lines. The square planar Pd (II) complex was more active than those of octahedral geometries of all other synthesized complexes. Cd (II) complex has the highest microbial growth inhibition than the rest of the prepared complexes. The docking active sites interactions were evaluated using the selected proteins EGFR tyrosine kinase and protein crystal structure of GlcN-O-P synthase. in vitro antioxidant assay revealed potent free radical scavenging activity of the three synthesized Cu (II), Pd (II) and Rh (III) complexes that exceeded the standard ascorbic acid. Pd (II) complex shows the most significant inhibition denaturation percent.
- Hassan, Safaa S.,Khalf-Alla, Perihan A.
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- Pharmacological properties of dicyanidoaurate(I)-based complexes: characterization and single crystal X-ray analysis
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Absract: The synthesis of three bimetallic cyanido complexes with edbea [2,2′-(ethylenedioxy)bis(ethylamine)] ligand is reported. [NiII(μ-edbea)2{Au(μ-CN)2}2]n (1), [{CuII(edbea)}2{Au(μ-CN)2}4]n (2) and [CdII(edbea)2][Au(CN)2]2·H2O (3) were fully characterized by elemental, infrared, XRD (3), ESI-MS and thermal analysis. The DNA/BSA binding properties of these complexes were evaluated by spectrophotometric titration, fluorometric ethidium bromide kinetics, and DNA electrophoresis studies and their partially minor groove binding mode between the base pairs of DNA and electrostatic interaction between the amino acid residues of BSA were explained. The complexes were tested for their pharmacological properties. These molecules had excellent in vitro antiproliferative activity and also exhibited a strong tumor inhibiting effect against HT29, HeLa, C6 and Vero cell lines. These complexes had metastatic features as they are able to reduce cell migration activity and suppress tumor growth in vitro. Analysis of the DNA topoisomerase I relaxing activity indicates that the complexes do not inhibit topoisomerase I which regulates the topological states of the DNA double helix during DNA processing reactions. The TUNEL and DNA laddering assay results indicated that these compounds may destroy cell maintenance by triggering apoptosis. Immunohistochemistry staining analysis demonstrated that these complexes significantly decreased the expression of Bcl-2 in HeLa and HT29 cells while increasing the expression of P53 levels. Overall, the potent antiproliferative activity, low cytotoxic effect, good solubility, and micro molar range dosage observed for these complexes emphasizes their potential as anticancer drug candidates.
- Karada?, Ahmet,Aydin, Ali,Tekin, ?aban,Akba?, Hüseyin,Dede, Süreyya
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p. 860 - 878
(2019/03/11)
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- Schiff base metal complexes of 4-methyl-1H-indol-3-carbaldehyde derivative as a series of potential antioxidants and antimicrobial: Synthesis, spectroscopic characterization and 3D molecular modeling
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Novel mononuclear Fe(III), Cu(II), Cd(II), Sn(IV) and binuclear Ni(II) and Hg(II) complexes with the Schiff base ligand: (E)-N'-((4-methyl-1H-indol-3-yl)methylene) nicotinohydrazide were synthesized. The elucidation of the structure of the prepared compounds were performed by elemental analyses, magnetic measurements, thermogravimetry, 3D molecular modeling, molar conductance techniques and by various spectroscopic (IR, 1H NMR, UV–Visible, EPR) tools. Antioxidant activity in vitro by DPPH scanning of the ligand and its metal complexes was studied. The results indicated that all test compounds are excellent antioxidants and better than the standard (Ascorbic acid).[Sn(HL)Cl2(OH)2]·2H2O complex (5) showed the highest antioxidant activity. Moreover, the ligand and its metal complexes were screened against the sensitive organisms Staphylococcus aureus as Gram-positive bacteria, Escherichia coli as Gram-negative bacteria and two strains of fungi (Aspergillus flavus and Candida albicans). The results showed that all metal complexes have higher antimicrobial activity than the metal free ligand and the binuclear [Hg2(HL)Cl4]·EtOH complex (6) possessed excellent antibacterial activity better than the standard drug Ampicillin (antibacterial agent) and showed excellent antifungal activity against Aspergillus flavus, better than Amphotericin B (antifungal agent).
- EL-Gammal, Ohyla A.,Alshater, Heba,El-Boraey, Hanaa A.
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p. 220 - 230
(2019/06/18)
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- Molecular modeling, spectral investigation and thermal studies of the new asymmetric Schiff base ligand; (E)-N'-(1-(4-((E)-2-hydroxybenzylideneamino)phenyl)ethylidene)morpholine-4-carbothiohydrazide and its metal complexes: Evaluation of their antibacterial and anti-molluscicidal activity
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A new tetradentate asymmetric Schiff base ligand; (E)-N'-(1-(4-((E)-2-hydroxybenzylideneamino)phenyl)ethylidene)morpholine-4-carbothiohydrazide (H2L) was prepared by consecutive condensation reactions between p-aminoacetophenone, salicylaldehyde and 4-morpholinethiosemicarbazide. The structures of the obtained ligand along with its Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Cr(III), Fe(III) and Ru(III) complexes were authenticated by different analytical and spectral techniques. The ligand behaves as a monobasic tetradentate one and chelates with metal ions through the deprotonated phenolic oxygen, imine nitrogen, thione sulfur and azomethine nitrogen atoms (ONNS chromophore). All nonelectrolyte metal complexes possess octahedral geometry, except Ni(II) and Cu(II) complexes (2, 3) which have tetra-coordinate structures. The thermal stability of metal complexes is higher than that of the free ligand and the general thermal degradation pathways were discussed based on thermogravimetric technique. The activation thermodynamic parameters as well as the order of reaction (n) were estimated from DTG curves by using Piloyan method. Thermogravimetric analyses and mass spectra of metal complexes confirm the number of solvents in their inner and outer spheres. Molecular modeling data were used to demonstrate the thermal decomposition pathways of the ligand and its metal complexes, confirming their chemical structures. The ESR spectra of Cu(II) complexes indicate that the unpaired electron is localized mainly in the d(x 2 -y 2 ) orbital with axial symmetry. Powder X-ray diffraction analyses for Co(II), Cu(II) and Ru(III) complexes (1, 3, 7) show that copper complex has a crystalline nature, whereas, cobalt and ruthenium complexes are amorphous. The ligand and its metal complexes were tested in vitro for their anti-molluscicidal activity against Eobania vermiculata. The results reveal that the investigated compounds have remarkable anti-molluscicidal activities against the tested land snail with various sensitivity levels. The synthesized compounds were also screened in vitro for their antibacterial activity against Gram-positive bacteria; Staphylococcus aureus and Gram-negative bacteria; Escherichia coli and the results were compared with the activity of ceftriaxone. The data show that all investigated compounds display a high antibacterial activity against the tested bacterial strains with different inhibition degrees and the activity is significantly higher against Staphylococcus aureus than Escherichia coli.
- El-Samanody, El-Sayed A.,AbouEl-Enein, Saeyda A.,Emara, Esam M.
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- Quantum Dots in Visible-Light Photoredox Catalysis: Reductive Dehalogenations and C-H Arylation Reactions Using Aryl Bromides
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In the recent past, visible-light-mediated photoredox catalysis has made a huge impact on the development of new synthetic methods under very mild and ecologically benign conditions. Although semiconductor nanocrystals or quantum dots (QDs) possess suitable optoelectronic and redox properties for photoredox catalytic applications, surprisingly, their use for the activation of challenging chemical bonds in the synthesis of organic molecules is little explored. We report here the application of ZnSe/CdS core/shell QDs for the synthetically important photoredox catalytic activation of carbon-halogen bonds in dehalogenation and C-H arylation reactions using (hetero)aryl halides as bench-stable inexpensive bulk starting materials, under very mild reaction conditions. The outstanding catalytic activity of ZnSe/CdS core/shell QDs is a direct consequence of the high specific surface area and homogeneity of QDs in solution and their high photostability toward oxidation.
- Pal, Anuushka,Ghosh, Indrajit,Sapra, Sameer,K?nig, Burkhard
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p. 5225 - 5231
(2017/07/04)
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- New bimetallic dicyanidoargentate(I)-based coordination compounds: Synthesis, characterization, biological activities and DNA-BSA binding affinities
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Four compounds -two (2 and 3) completely new- of composition [Ni(edbea)Ag3(CN)5] (1), [Cu(edbea)Ag2(CN)4]·H2O (2), [Cd(edbea)Ag3(CN)5]·H2O (3) and [Cd(edbea)2] [Ag(CN)2]2·H2O (4) {edbea; 2,2′-(ethylenedioxy)bis (ethylamine)}, were synthesized and characterized using elemental, FT-IR, X-Ray (4), thermal, variable temperature magnetic measurement (1 and 2) and biological techniques. The DNA/BSA binding affinities of 2 and 3 were evaluated by UV–Vis spectrophotometric titrations, ethidium bromide exchange experiments and electrophoretic mobility measurements. Compounds 1 and 4 have previously been characterized and shown to reduce the proliferation and migration of tumor cells. For the sake of clarity, 1 precise mechanism of action on microbial organisms and temperature magnetic measurement were determined. The crystallographic analyses showed that 4 was built up of [Cd(edbea)2]II cations and [Ag2(CN)4]II anions. Complexes demonstrated a remarkable antibacterial (1–4), antifungal (1–4) and antiproliferative activities (2 and 3) to ten human bacterial pathogens, four plant pathogenic fungi or three tumor cells (HeLa, HT29, and C6), respectively. Therefore, our results strongly confirm that cell proliferation, cell morphology, Bcl-2, P53 changes and apoptosis can be related to the pharmacological effects of the complexes as suitable candidate for clinical trials.
- Korkmaz, Nesrin,Ayd?n, Ali,Karada?, Ahmet,Yanar, Yusuf,Maa?o?lu, Yelis,?ahin, Ertan,Tekin, ?aban
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supporting information
p. 1007 - 1022
(2016/12/16)
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- Reactions of Cd(OAc)2·2H2O with variously substituted pyridines. Efforts to unravel the factors that determine structure/nuclearity of the products
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The reactions of Cd(OAc)2·2H2O with variously substituted pyridines in methanol afforded unique one-dimensional coordination polymers (1D CPs), [Cd2(μ2-κ2:κ1-OAc)2(μ2-κ1:κ1-OAc)2L2] (L = NC5H5 (1), NC5H4Me-3 (2), and NC5H3Me2-3,5 (3)) and [Cd3(μ3-κ1:κ2-OAc)3(μ2-κ2-OAc)(μ2-κ2:κ1-OAc)2(NC5H3Me2-3,4)2] (4), and discrete and bimolecular complexes, [(Cd(OAc)2(NC5H3Me2-3,4)2(H2O)2] (5), [Cd(κ2-OAc)2(NC5H4Me-4)2(H2O)]·[Cd(κ2-OAc)2(H2O)2)] (6), [Cd(κ2-OAc)2L2L′]·xH2O (x = 0, L′ = H2O, L = NC5H4(OMe)-4 (7); NC5H4tBu-4 (8); x = 2, L = L′ = NC5H4(NMe2)-4 (9·2H2O)). The products were characterised by elemental analysis, IR, solution NMR (1H and 13C), solid-state CP-MAS 13C{1H} and 113Cd NMR, TGA/DTA analyses, and single crystal X-ray diffraction. Phase purity of 1-4 was verified by powder X-ray diffraction (PXRD). Plausible mechanisms of formation of the products are proposed based on a point zero charge model. 4 represents the first cadmium containing 1D CP that possesses a tridentate bridging (μ3-κ1:κ2) acetate coordination mode and 6 represents the first structurally characterised bimolecular cadmium(II) complex containing two different neutral cadmium(II) coordination species per formula unit. 9·2H2O was calcined at 500 °C to afford CdO as confirmed by PXRD and the morphology of CdO was studied by scanning electron microscopy.
- Saxena, Priya,Thirupathi, Natesan
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supporting information
p. 238 - 250
(2015/07/27)
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- A comparative study of the synthesis of CdO nanoplatelets by an albumen-assisted isothermal evaporation method
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In this paper, the synthesis of CdO nanoplatelets by the isothermal evaporation method in the presence of egg white (albumen) as a bio-template agent is reported for the first time. The morphological and microstructural characteristics of products obtained after drying at 130 °C and annealing at 300 °C have been investigated by Fourier transform infrared (FT-IR) spectroscopy, Thermogravimetric analysis (TGA), X-ray diffraction (XRD), SEM (Scanning Electron Microscopy), Transmission Electron Microscopy (TEM), Energy Dispersive Spectroscopy (EDS), and compared with corresponding samples obtained in the absence of template. The characterization techniques evidenced remarkable differences between the two sample typologies. Specifically, crystalline CdO in the cubic phase was obtained only in the presence of albumen. The samples were further analyzed by electrical conductivity measurement, ultraviolet spectral studies (UV) and photoluminescence (PL) to ascertain their possible use for optical and electrical applications.
- Prakash,Neri,Ranjith Kumar
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p. 258 - 265
(2015/02/19)
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- Phase identification in electrodeposited Ag-Cd alloys by anodic linear sweep voltammetry and X-ray diffraction techniques
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During electrodeposition of Ag-Cd alloy coatings phenomena of self-organization and formation of spatio-temporal structures can be observed. The difficulties in the determination of the local phase composition in the observed structures are mostly connected with the strong heterogeneity of the coatings consisting of several alloy phases. The results obtained with electrochemical techniques, such as anodic linear sweep voltammetry (ALSV) are compared with results obtained by X-ray analysis and SEM. In the proposed electrolyte for dissolution of Ag-Cd alloy coatings (12 M LiCl + 0.1 M HCl) the dissolution peaks of the pure metals, Ag and Cd, have a potential difference of about 700 mV. The peaks, corresponding to the alloy phases, are situated between the dissolution potentials of Ag and Cd, their height depending on the deposition current density, i.e. on the percentage content of the alloy. Different phases (Ag, Ag3Cd, AgCd, AgCd3 and pure Cd) are observed in the coatings deposited at different cathodic potentials. A good correlation between the XRD spectra of the Ag-Cd alloy coatings and the ALSV data obtained during their dissolution is established.
- Dobrovolska,Krastev,Jovi?,Jovi?,Beck,La?njevac,Zielonka
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p. 4344 - 4350
(2011/07/29)
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- Behavior of electrodeposited cd and pb schottky junctions on C H3 -Terminated n-Si(111) Surfaces
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n-SiCd and n-SiPb Schottky junctions have been prepared by electrodeposition of Cd or Pb from acidic aqueous solutions onto H-terminated and C H3 -terminated n-type Si(111) surfaces. For both nondegenerately (n-) and degenerately (n+ -) doped H-Si(111) el
- Maldonado, Stephen,Lewis, Nathan S.
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p. H123-H128
(2009/04/13)
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- FT-IR spectroscopic investigation of some Hofmann type complexes: M(1-phenylpiperazine)2Ni(CN)4 (M = Ni, Co, Cd, Pd or Mn)
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New Hofmann type complexes in the form of M(pp)2Ni(CN)4 (where pp = 1-phenylpiperazine and M = Ni, Co, Cd, Pd or Mn) have been prepared in powder form and their infrared spectra have been reported in the range of (4000-400) cm-1
- Senyel, Mustafa,Parlak, Cemal,Alver, Oezguer
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p. 367 - 375
(2008/09/21)
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- Spectral, thermal, electrochemical and analytical studies on Cd(II) and Hg(II) thiosemicarbazone complexes
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The coordination characteristic of the investigated thiosemicarbazones towards hazard pollutants, Cd(II) and Hg(II), becomes the first goal. Their complexes have been studied by microanalysis, thermal, electrochemical and spectral (electronic, IR and MS) studies. The substitutent (salicylaldehyde, acetophenone, benzophenone, o-hydroxy-p-methoxybenzophenone or diacetylmonoxime) plays an important role in the complex formation. The coordination sites were the S for thiosemicarbazide (HTS); NN for benzophenone thiosemicarbazone (HBTS); NS for acetophenone thiosemicarbazone (HATS) and salicylaldehyde thiosemicarbazone (H2STS); NNS or NSO for diacetylmonoxime thiosemicarbazone (H2DMTS). The stability constants of Hg(II) complexes were higher than Cd(II). The kinetic and thermodynamic parameters for the different thermal decomposition steps in the complexes have been evaluated. The activation energy values of the first step ordered the complexes as: [Cd(H2STS)Cl2]H2O > [Cd(H2DAMTS)Cl2] > [Cd(HBTS)2Cl2]2H2O > [Cd(HATS)2Cl2]. The CV of [Cd(H2STS)Cl2]H2O and [Hg(HBTS)Cl2] were recorded. The use of H2DMTS as a new reagent for the separation and determination of Cd(II) ions from water and some synthetic samples using flotation technique is aimed to be discussed.
- El-Asmy,El-Gammal,Saleh
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- Synthesis, spectroscopic and thermal studies of transition metal complexes derived from benzil and diethylenetriamine
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A macrocyclic ligand, bdta (where bdta = 3,6,9,12,15,18-hexaaza-1,2,10,11-tetraphenyl-2,9,11,18-tetraenecyclododecane) has been prepared by cyclocondensation of benzil with diethylenetriamine which efficiently encapsulates transition as well as pseudo-transition metal ions leading to the formation of M(bdta)Cl2 type complexes [where M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II)]. The analytical, spectroscopic and magnetic moment data suggests an octahedral geometry for all the complexes. EPR spectra of Mn(II) and Cu(II) show considerable exchange interaction in the complex. They are non-conducting in DMSO. The TGA profile of the ligand and its complexes are identical and consists of two discreet stages. The voltammogram of Cu-complex exhibits a quasi-reversible one-electron transfer wave for Cu(II)/Cu(I) couple.
- Khan, Sadaf,Nami, Shahab A.A.,Siddiqi
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p. 269 - 274
(2008/02/13)
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- Thermal decomposition of Cd(CH3COO)2· 2H 2O studied by a coupled TG-DTA-MS method
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The thermal decomposition of cadmium acetate dihydrate in helium and in air atmosphere has been investigated by means of a coupled TG-DTA-MS method combined with X-ray diffraction analysis. Dehydration of Cd(CH 3COO)2·2H2O is a two-stage process with Cd(CH3COO)2H2O as intermediate. The way of Cd(CH3COO)2 decomposition strongly depends on the surrounding gas atmosphere and the rate of heating. CdO, acetone and CO 2 are the primary products of decomposition in air. In helium decomposition goes by two parallel and consecutive reactions in which intermediates, Cd and CdCO3, are formed. Metallic cadmium oxidizes and cadmium carbonate decomposes giving CdO. Some of the metallic cadmium, depending on the heating rate and the concentration of oxygen, evaporates. Acetone is partially oxidized in secondary reactions with oxygen.
- Malecka, Barbara
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p. 535 - 544
(2008/10/09)
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- EC-STM studies of Te and CdTe atomic layer formation from a basic Te solution
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The cyclic volitammetry of Te on Au is markedly affected by pH. This fact can be used to advantage when designing an electrodeposition cycle for CdTe. For instance, if a pH 2 Te solution is used, the underpotential deposition (UPD) potential for Te is 0.8 V positive of that for Cd. However, if a pH 9.2 Te deposition solution is used, the potential for Te UPD coincides with that for Cd, greatly simplifying the development of an electrochemical atomic layer epitaxy (EC-ALE) cycle. This report describes electrochemical scanning tunneling microscopy (EC-STM) studies of Te deposition on Au(111) and Au(100) from basic media. Several structures were observed on Au(111): a (6 × 6) tellurite adlayer which spontaneously adsorbed prior to Te formation, a 1/4 coverage (2 × 2)-Te, and a 1/3 coverage (2 × √10)-Te. While on Au(111), a 1/3 coverage (√3 × √3)-Te with (13 × 13) light domain walls, and two (3 × 3)-Te structures, with coverages of 4/9 and 5/9, were observed. Results of the formation of the first CdTe compound monolayer using an EC-ALE cycle which includes Te deposition from a basic solution are also included.
- Lay, Marcus D.,Stickney, John L.
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p. C431-C435
(2008/10/09)
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- Free Radical-Mediated Heterogeneous Photocatalytic Reduction of Metal Ions in UV-Irradiated Titanium Dioxide Suspensions
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This paper describes the indirect photocatalytic reduction of four metal ions: Cd2+, Zn2+, Mn2+, and Tl+ using formate radical anions (CO2.-) generated in UV-irradiated aqueous TiO2 suspensions. Trends in the reactivity of these four metal ions are compared with corresponding rate constants reported in the literature for the homogeneous reactions of these metal ions with CO 2.- in aqueous media. In both cases, the reaction rates follow the same order: Cd2+ > Tl+ > Mn2+ > Zn2+. Using Tl+ as a model metal ion, a simple kinetics scheme is developed for the indirect reduction route, and the predictions from this model are shown to be in excellent agreement with experimental data.
- Somasundaram, Sashikala,Ming, Yong,Chenthamarakshan,Schelly, Zoltan A.,Rajeshwar, Krishnan
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p. 4784 - 4788
(2007/10/03)
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- Interaction of Pb and Cd during anodic stripping voltammetric analysis at boron-doped diamond electrodes
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Highly boron-doped diamond (BDD) films were utilized for simultaneous electrochemical measurement of micromolar-level concentrations of Pb and Cd, and for the examination of their interactions. Differential pulse anodic stripping voltammetry (DPASV) was used for this detection. This approach can help to understand the possible detection of trace metals at BDD electrodes without the aid of mercury. These metals were found to strip at their characteristic potentials, in solutions containing Cd or Pb alone, and in those containing these metals together. The mixed solutions (concentration range: 1-5μM) yielded well-separated stripping peaks for Pb and Cd and the differential stripping peak currents for the respective metals increased linearly with increasing metal concentration. There were mutual interferences due to Pb-Cd interactions, but these can be taken into account with the aid of three-dimensional calibration plots. A model has been developed to help explain the Pb-Cd interactions.
- Manivannan,Kawasaki,Tryk,Fujishima
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p. 3313 - 3318
(2008/10/09)
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- Synthesis and characterization of 3,3′-bis(N-ferrocenyl methylene formylhydrazone)-2,2′-bipyridyl and its Cd(II), Hg(II), Cu(II), and Mn(II) Complexes
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In this article, 3,3′-bis(N-ferrocenylmethylene formylhydrazone)-2, 2′-bipyridyl and its Cd(II), Hg(II), Cu(II), and Mn(II) complexes have been synthesized and characterized by elemental analyses, IR, 1H NMR spectral, thermal analyses, and molar conductances. In the complexes, 3,3′-bis(N-ferrocenylmethylene formylhydrazone)-2,2′-bipyridyl coordinates to the transition metal ions using a methylenimine nitrogen, the amide oxygen in the enolic form, the pyridyl nitrogen, the acetate in a symmetrical bidentate manner, and one water molecule, all of which participate in coordination to form a binuclear complex. The ligand and the complexes are insoluble in common organic solvents and slightly soluble in strongly polar solvents such as DMF and DMSO.
- Wu, Ben-Lai,Liu, Cheng-Xiang,Yao, Ming-Xing,Zhang, Hong-Yun,Chen, Pei-Kun,Mao, Hong-Yan,Shen, Xiao-Qing,Liu, Shou-Chang
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p. 1709 - 1719
(2008/10/09)
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- Photoassisted electrodeposition of CdTe layer from ammoniacal basic aqueous solutions
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Potentiostatic cathodic electrodeposition of CdTe on gold substrate under irradiation of visible light was studied using basic aqueous electrolytic baths in which Cd(II) and Te(IV) species were dissolved to form Cd(NH3)42- and TeO32- ions, respectively. Both deposition current density and current efficiency for the CdTe deposition were enhanced by photoirradiation and, as a result, the time required for a given amount of deposition was dramatically shortened. The photoirradiation also resulted in a slight increase in cadmium content of the CdTe deposits and, in some cases, elemental Cd was deposited by underpotential codeposition. The cathodic polarization curve under pulsed photoirradiation showed a photoresponse in cathode current at potentials negative to the Nernst potential of CdTe deposition and the photoresponse was observed for wavelengths lower than that corresponding to the bandgap of CdTe, suggesting that the response was due to the CdTe itself growing on the cathode surface. The mechanism of the photoassist is discussed in terms of photoconduction of low-conducting CdTe semiconductors.
- Murase, Kuniaki,Matsui, Masaki,Miyake, Masao,Hirato, Tetsuji,Awakura, Yasuhiro
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- Interaction of oxides with supercritical isopropanol
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The interaction of Group I-VIII oxides with isopropanol (i-C 3H7OH; i-PrOH) in the supercritical fluid (SCF) region has been studied. Simple oxides can be divided into three groups: (a) oxides that are completely reduced to a metal (CuO, CdO, PbO, TeO2, Sb 2O3, Bi2O3, Co2O 3, ReO3, PtO2), (b) polyvalent metal oxides reducible to intermediate (lower) oxidation states (V2O5, Fe 2O3, MnO2, Mn2O3, MoO3) and (c) ones irreducible by SCF-/-PrOH (UO2, Ga 2O3, SnO2, ZnO, In2O3, Nd2O3, Cr2O3, WO3, ZrO2, NiO, CeO2, SiO2, GeO2). It has been found that in the cases of MnO2 and Nd2O3 the oxides can be hydrogenated to yield hydroxides. For the reactions of C 3H7OH with bismuth and manganese oxides, it has been shown that the process is heterogeneous during its entire duration.
- Kargin,Buslaeva,Kravchuk,Gubin
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p. 103 - 106
(2008/10/08)
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- Preparation of metal alkoxides
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Methods of forming metal alkoxides and methods of forming precursor solutions of metal alkoxides suitable for the coating of glass in the manufacture of electrochromic devices are disclosed. The method of forming metal alkoxides involves dissolving the metal halide in an anhydrous solvent and reacting it with an alcohol and (together with the addition of the alcohol or subsequently) adding an epoxide, and then evaporating-off the volatile components of the reaction product to leave a solid metal alkoxide that is substantially free of halide. The alkoxide may then be dissolved in a solvent including an alcohol (preferably ethanol) containing a small proportion of water to produce a precursor solution suitable for coating glass, the coating then being hydrolyzed to form a sol-gel and then baked to remove volatile components and to yield a thin layer of metal oxide.
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