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PubMed2005

catena-Poly[[bis[mu-2,4-dichloro-6-(2-pyridylmethyliminomethyl)phenolato]dicadmium(II)]-di-mu-thiocyanato].

The title complex, [Cd2(C13H9Cl2N2O)2(NCS)2]n, is a novel thiocyanate-bridged polynuclear cadmium(II) compound. The Cd(II) atom is six-coordinated in a distorted octahedral configuration, with one O and two N atoms of one Schiff base molecule and one terminal S atom of a bridging thiocyanate ligand defining the equatorial plane, and one terminal N atom of another bridging thiocyanate ligand and one O atom of another Schiff base molecule occupying axial positions. Adjacent inversion-related [2,4-dichloro-6-(2-pyridylmethyliminomethyl)phenolato]cadmium(II) moieties utilize bridging phenolate and thiocyanate groups to form polymeric chains running along the b axis.

Journal Article↗
PubMed2005

Determination of cadmium, zinc, nickel and cobalt in tobacco by reversed-phase high-performance liquid chromatography with 2-(8-quinolylazo)-4,5-diphenylimidazole as a chelating reagent.

A sensitive and selective method has been developed for the simultaneous determination of cadmium, zinc, nickel and cobalt. The method is based on the chelation of metal ions with 2-(8-quinolylazo)-4,5-diphenylimidazole (QAI) and the subsequent reversed-phase (RP) high-performance liquid chromatographic separation and spectrophotometric detection of the metal chelates. The chelates were separated on an RP column with acetonitrile-water containing ethylenediamine tetraacetic acid and sodium acetate (pH 7.5). Though Zn(II) and Cd(II) chelates with azo compounds were generally labile in the RP column, these chelates with QAI were successfully detected. When analyses were carried out at 575 nm and at 0.001 absorbance unit full scale, the peak height calibration curves were linear up to 2.0 ng for Cd(II), 2.4 ng for Zn(II), 0.14 ng for Ni(II) and 0.72 ng for Co(II) in 100-microL injections, respectively; the detection limits (3sigma, three times of the standard deviation for the blank signal) for Cd(II), Zn(II), Ni(II) and Co(II) were 4.8, 24, 2.4 and 7.2 pg in 100 microL of injected solution, respectively. The proposed method was successfully applied to the analysis of tobacco without any preliminary concentration or separation.

Animals↗
PubMed2005

Structural models for the interaction of Cd(II) with DNA: trans-[Cd(9-RGH-N7)2(H2O)4]2+.

Reactions of Cd(NO(3))(2) with the model nucleobases 9-alkylguanine in water at neutral pH, give the compounds trans-[Cd(9-RGH-N7)(2)(H(2)O)(4)](NO(3))(2)(R=Me, Et), with the 9-alkylguanine ligands bound to the metal cation at the N(7) position. The X-ray structures of both compounds are reported. The six-coordinate Cd(II) complexes consist of a highly regular octahedral geometry in which the two 9-alkylguanine ligands are in a trans position to each other and approximately collinear with the metal cation. In addition, the networks of both compounds show interesting features. Thus, intramolecular H-bonds between O(6) and a coordinated water molecule are present, and self-association of guanines via H-bonding of N(3)-H...N(2) take place, leading to a 1D supramolecular polymeric ribbon. Density functional theory calculations have been applied to both compounds in order to study the stability of N(7) metalated guanine-guanine associations by comparing experimental and theoretical results. The potential relevance with regard to possible Cd(II)-DNA cross-links is briefly discussed.

Cadmium Compounds↗
PubMed1998

Histochemical staining of chromium with 2-(8-quinolylazo)-4,5-di-p-tolylimidazole.

A new highly sensitive staining agent for chromium (Cr) has been introduced. This staining agent, 2-(8-quinolylazo)-4,5-di-p-tolylimidazole (QTI), was found to be more than ten times as sensitive for Cr than the conventional staining agent, Chromazurol S, and QTI also stained cadmium, copper, lead and zinc. Differentiation between the staining of Cr and other metals was achieved by immersing the tissue sections in dilute alkylamine solutions before they were stained with QTI. Thus, it was possible to selectively stain for Cr by blocking other metals.

Animals↗
PubMed1985

Diamide blocks H+ conductance in mitochondrial H+-ATPase by oxidizing FB dithiol.

Effects of diamide on proton conductance of electron transport particles (ETPH), purified H+-ATPase (F1-F0), F0 of the H+-ATPase from beef heart mitochondria and binding of cadmium (109Cd) to the H+-ATPase have been examined in the present paper. When ETPH and purified H+-ATPase are treated with 1 mM diamide, ATP-dependent generation of membrane potential, monitored by the absorbance change produced by the redistribution of oxonol VI, is consistently inhibited. Diamide also blocks passive H+ conductance driven by a K+ diffusion potential in the membrane sector, F0, of H+-ATPase. Furthermore, diamide treatment drastically reduces the binding of 109Cd2+ to H+-ATPase, showing competition for the FB dithiol group.

Adenosine Triphosphatases↗
PubMed2001

Bisphenol A enhances cadmium toxicity through estrogen receptor.

To clarify the action of estrogenic endocrine disruptors on cadmium (Cd)-induced metallothionein (MT) synthesis in the liver, we investigated the effects of bisphenol A (BPA) on hepatic MT-I mRNA expression and MT contents after Cd injection. Liver damage after Cd injection was assessed by measuring glutamic-pyruvic transaminase (GPT) and glutamic-oxaloacetic transaminase (GOT) activities in the serum. It was found that BPA reduced the Cd-induced expression of MT-I mRNA and MT protein in the liver. The administration of tamoxifen, an estrogen receptor antagonist, prevented the reduction of hepatic MT content by PA. Moreover both the GPT and GOT activities of the BPA-treated groups were higher than those of the control groups. These findings suggest that BPA reduced hepatic MT synthesis after Cd injection via the estrogen receptor which resulted in increased damage to the liver.

Alanine Transaminase↗
PubMed2006

Cadmium-113 NMR studies on homoleptic complexes containing thioether ligands: the crystal structures of [Cd([12]aneS4)2](ClO4)2, [Cd([18]aneS4N2)](PF6)2 and [Cd([9]aneS3)2](PF6)2.

We report the measurement of 113Cd NMR chemical shift data for homoleptic thioether and related aza and mixed aza/thiacrown complexes. In a series of Cd(II) complexes containing trithioether to hexathioether ligands, we observe solution 113Cd NMR chemical shifts in the range of 225 to 731 ppm. Upfield chemical shifts in these NMR spectra are seen whenever: (a) the number of thioether sulfur donors in the complex is decreased, (b) a thioether sulfur donor is replaced by a secondary nitrogen donor, or (c) the size of the macrocycle ring increases without a change in the nature or number of the donor atoms. Changes in the identity of non-coordinating anions such as perchlorate or hexafluorophosphate have little effect upon the 113Cd NMR chemical shift in solution. We report the X-ray structure of the complex [Cd([12]aneS4)2](ClO4)2 ([12]aneS4 = 1,4,7,10-tetrathiacyclododecane) (1) which shows the first example of octakis(thioether) coordination of a metal ion, forming an unusual eight-coordinate square antiprismatic structure. We report the X-ray structure of the complex [Cd([9]aneS3)2](PF6)2 ([9]aneS3 = 1,4,7-trithiacyclononane) (3a) which shows hexakis(thioether) coordination to form a distorted octahedral structure. We have also prepared and characterized the Cd(II) complex of a mixed azathiacrown, [Cd([18]aneS4N2)](PF6)2 ([18]aneS4N2 = 1,4,10,13-tetrathia-7,16-diazacyclooctadecane) (6). Its X-ray structure shows a distorted octahedral S4N2 environment around the Cd(II) with the ligand coordinated in the rac fashion. We observe a solvent- and temperature-dependent 14N-1H coupling in the 1H NMR spectrum of the complex which is not present in analogous complexes with this ligand.

Aza Compounds↗
PubMed2004

Comparison between acetic acid and landfill leachates for the leaching of Pb(II), Cd(II), As(V), and Cr(VI) from cementitious wastes.

The Toxicity Characteristic Leaching Procedure (TCLP) has been widely used to characterize the suitability of solid wastes for disposal in landfills. However, the widespread application of this test for the assessment of wastes disposed in different landfill types is often questionable. This paper investigates the leaching profiles of cement-stabilized heavy metal ions, namely, Pb (II), Cd (II), As(V), and Cr(VI), using acetic acid and leachates from municipal and nonputrescible Australian landfill sites. The leaching profiles of Pb, Cd, As, and Cr using acetic acid were found to be similar to the nonputrescible landfill leachate and differed markedly from the municipal solid waste (MSW) leachate. The additional presence of high amounts of organic and inorganic compounds in the municipal landfill leachate influenced the leaching profiles of these metal ions as compared to the acetic acid and the nonputrescible systems. It is postulated that the organic compounds present in the municipal landfill leachate formed complexes with the Pb and Cd, increasing the mobility of these ions. Moreover, the organic compounds in the municipal landfill leachate induced a reducing environment in the leachate, causing the reduction of Cr(VI) to Cr(III). It was also found that the presence of carbonates in the municipal landfill leachate affected the stability of calcium arsenate, with the carbonate competing with arsenate for calcium at high pH, forcing arsenate into the solution.

Acetic Acid↗
PubMedDate not supplied

Solid-state 29Si, 113Cd, 119Sn, and 31P NMR studies of II-IV-P2 semiconductors.

Solid-state 29Si, 113Cd, 119Sn, and 31P MAS NMR spectra are reported on a series of II-IV-P2 compounds. In favorable cases (e.g., high degree of crystallinity, low concentration of unpaired electrons), well-defined spectra, with sharp lines for each specific nearest-neighbor configuration, are observed; in such cases, expected J coupling patterns are also seen. High-resolution solid-state NMR studies of this type provide useful information on structure (disorder), doping, and electron-mediated coupling in semiconductor systems.

Cadmium↗
PubMed1996

Histochemical staining of cadmium with 2-(8-quinolylazo)-4,5-diphenylimidazole.

In order to develop a stain with increased sensitivity and selectivity for cadmium (Cd), we synthesized and characterized 2-(8-quinolylazo)-4,5-diphenylimidazole (QAI). This chelating agent was more than twice as sensitive for Cd than the best conventional staining agents, including benzothiazolylazo-beta-naphthol. Differentiation between Cd and zinc (Zn) was achieved by immersing tissue sections in TRIS(2-aminoethyl)amine before they were stained with QAI. This pretreatment made it possible to selectively stain for Cd by blocking Zn.

Animals↗
PubMed2001

Simple regression model using an optode for the simultaneous determination of zinc and cadmium mixtures in aqueous samples.

An optical-fiber chemical sensor (optode) is described for the simultaneous determination of Zn2+ and Cd2+ mixtures using 2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenol immobilized onto XAD-4 (Br-PADAP/XAD-4). A simultaneous analysis was achieved by using a single-wavelength kinetic approach coupled with a regression model. Here, the regression model was derived for the slope response of Br-PADAP/XAD-4 to binary mixtures of the metal ions, Zn2+ and Cd2+, at pH 8. The model was used then to predict the concentration of one metal ion while the other was kept constant. This was found to be reasonably successful for Zn2+ and Cd2+, with deviations of 3% and 10%, respectively. The sensor was also found to provide excellent sensitivity for both metal ions with excellent LODs (< 0.1 ppm) and very short analysis times (< 30 s).

Azo Compounds↗
PubMed2004

Preparation of nanosized ZnS-passivated CdS particle films via the MOCVD process with co-fed single source precursors.

A novel approach was developed to prepare thin films of nanosized ZnS-passivated CdS particles via a metal-organic chemical vapor deposition (MOCVD) process with co-fed single source precursors of CdS and ZnS. Single source precursors of CdS and ZnS with sufficiently different reactivity, as judged from thermogravimetry analysis, were prepared and paired up to form ZnS-passivated CdS, (CdS)ZnS, and CdS-modified ZnS, (ZnS)CdS, particle films in a one-step process. For comparison purposes, sequential layer growth of CdS/ZnS and ZnS/CdS particle films was also conducted, and single compound particle films were prepared. These films were characterized with absorption spectrometry, photoluminescence spectroscopy, scanning electron microscopy, and powder X-ray diffraction spectra. The photoluminescence efficiency of the resulting composite particle film of ZnS-passivated CdS was significantly enhanced as compared to that of the plain CdS film, due to the effective passivation of surface electronic states of CdS by ZnS, a material with a higher conduction band than that of CdS. As for particle films of CdS-modified ZnS, a decay in photoluminescence efficiency was observed. The enhancement or decay in photoluminescence efficiency was much more pronounced for the passivated and modified system than for the sequential layer system, proportional to the interfacial area between the CdS and ZnS phases.

Cadmium Compounds↗
PubMed1993

Effects of procymidone on reproductive organs and serum gonadotropins in male rats.

To investigate the mechanism and toxicological significance of testicular interstitial cell tumors (ICT) observed in a long-term rat study with procymidone, N-(3,5-dichlorophenyl)-1,2-dimethylcyclopropane-1,2-dicarboximi de, male Sprague-Dawley rats were fed procymidone in diets for up to 6 months with a positive control group receiving a single subcutaneous injection of cadmium chloride. Examinations mainly for gonadal functions such as serum testosterone and luteinizing hormone (LH), reproductive organ weight and histopathology presented evidence of the indirect involvement of gonadotropins in the production of ICT in rats. A significant increase in both serum testosterone and LH was observed in the early stage at high dietary concentrations of procymidone without any lesion in gonadal systems in histopathology, whereas administration of cadmium chloride produced the expected substantial increase in serum LH and a concomitant decrease in serum testosterone with a marked damaging effect on gonadal systems. Increases in serum testosterone and LH levels in animals receiving procymidone were reversible. The no-effect level for procymidone on serum testosterone and LH was 300 ppm over six months of treatment. The possible mechanism of ICT production in rats by non-genotoxic procymidone, structurally similar to flutamide, a synthetic non-steroidal antiandrogen, is likely to be derived from its induction of a hypergonadotropism due to the competitive binding to the androgen receptor, preventing the normal effect of testosterone to control the circulating level of LH.

Animals↗
PubMed2002

Stereochemistry, structural and models of novel 5-(4'-derivatives phenyldiazo)-3-phenyl-2-thioxo-4-thiazolidinone complexes.

Copper(II) and cadmium(II) complexes of 5-(4'-derivatives phenyldiazo)-3-phenyl-2-thioxo-4-thiazolidinone (HLn) were prepared, their compositions and physicochemical properties were characterized by elemental analysis, magnetic suseptibility measurements, and infrared, electronic spectra. The novel complexes have the stoichiometric formulae [Cu(HLn)(OAc)n(H2O)(X)] (OAc = acetate, X = H2O or acetate) and [Cd(L)(OAc)(H2O)], respectively. Elemental analysis and IR spectra denote, that two types of complexes with different octahedral and tetrahedral structure for Cu(II) and Cd(II) ions. I.R. spectra show that the ligand is monobasic/neutral bidentate forming thereby a six-membered chelating ring and concomitant formation of an intramolecular hydrogen bond. The stoichiometeries of these complexes were determined conductometrically and indicated the formation of 1:1 and 1:2 (metal:ligand) complexes.

Azo Compounds↗
PubMed2004

Pyrolytic and non-pyrolytic boron nitride platforms in electrothermal AAS for the determination of cadmium in sea and estuarine water without chemical modification.

The analytical performance of pyrolytic and non-pyrolytic boron nitride (PBN and NBN) platforms, attached to a commercially available graphite tube furnace, in electrothermal atomic absorption spectrometry (ETAAS) for Cd was studied. Although the tolerable pyrolysis temperature was 300 degrees C with the conventional pyrolytic graphite platform, it increased to 600 and 950 degrees C with the PBN and NBN platforms, respectively. The lifetime of the ceramic platform was 500 firings. The NBN platform provided an enhanced sensitivity with a better reproducibility than others. Using the NBN platform allowed the LOD, based on the variability of the blank (3sigma), to be 0.1 microg l(-1) within a seawater matrix (20,000 mg NaCl l(-1)) and a constant sensitivity in the range 0-30,000 mg NaCl l(-1). Good recovery in the range of 90-105% was observed for Cd (2.0 microg l(-1)) spiked into sea, estuarine and river water samples using the recommended procedure. This work proposes that using the NBN platform allows the direct monitoring and control of contaminated water for Cd by ETAAS without any chemical modification.

Boron Compounds↗
PubMed1982

Selective phagocytosis of crystalline metal sulfide particles and DNA strand breaks as a mechanism for the induction of cellular transformation.

Crystalline NiS, CuS, CoS2, and CdS particles were actively phagocytosed by cells and potently induced morphological transformation of Syrian hamster embryo cells in a concentration-dependent fashion. In contrast, the respective amorphous metal sulfide particles (amorphous NiS, CuS, CoS, and CdS) were not as actively phagocytosed by cultured cells and, in comparison to the crystalline form of these compounds, induced considerably less morphological transformation at both cytotoxic and noncytotoxic exposure levels. Chemical reduction of positively charged amorphous NiS with LiAlH4 resulted in active phagocytosis of these particles which was also associated with enhancement of cellular transformation. Crystalline but not amorphous NiS caused considerable strand breaks in the DNA of Chinese hamster ovary cells following 2 to 3 hr exposure at 10 micrograms/ml as determined by alkaline sucrose gradient techniques with subsequent determination of DNA molecular weight. Phagocytized inert particles such as latex beads did not induce transformation or DNA damage, suggesting that genotoxic dissolution products such as Ni2+ rather than the phagocytized particles are responsible for the observed DNA damage and cellular transformation. NiCl2 was about one-third to one-half as potent in inducing cellular transformation compared to crystalline NiS on a weight basis. These results correlate the selective phagocytosis of crystalline metal sulfides to their more potent activity in the induction of cellular transformation.

Animals↗
PubMed2002

[Spectral characteristics of CdSe/CdS nanocrystals].

Semiconductor nanocrystals appear different optical properties from their bulk analogous due to quantum confinement effects. It is well known that optical absorption of nanocrystals shift to higher energy as the sizes decrease, while the emission at the absorption band edge is always too weak to be investigated in details due to much nonradiative recombination at nanoparticle surface. To eliminate the surface defects, some kinds of materials such as organic molecules, polymers and inorganic compounds are used to overcoat the nanoparticles. It has been found that nanocrystals overcoated with high band gap inorganic materials maned core/shell type nanocrystals exhibit high photoluminescence intensity at band edge due to effective elimination of surface nonradiative recombination. In this article we report the characteristics of CdSe/CdS core/shell nanocrystals synthesized with mercapto acid as stabilizer. The effect of CdS shell on the electronic characteristics and the luminescence of CdSe core were investigated by using optical absorption, photoluminescence and photoluminescence excitation spectra. Large band edge luminescence enhancement was found in CdSe nanoparticles overcoated with the CdS shell with a thickness of 0.3 nm due to passivation of nonradiative recombination sites on CdSe surfaces. Such bandadge emission also appeared redshift from the absorption maximum. This Stokes shift of the emission peak from the absorption edge was explained by a model of formation of excimer among the small nanoparticles based on the optical experimental results and the theoretical calculation on fine structures of bandadge excitons.

Cadmium Compounds↗
PubMed2005

Optical properties of Ag/CdTe nanocomposite self-organized by electrostatic interaction.

Ag/CdTe nanocomposite was prepared via self-organization process by electrostatic interaction between positively charged CdTe quantum dots and negatively charged Ag nanoparticles and examined with respect to their optical properties. The positively charged CdTe quantum dots and negatively charged Ag nanoparticles were synthesized separately by modifying nanoparticles surface with cationic and anionic thiol compounds, respectively. The result showed that the mixing ratio of Ag nanoparticles to CdTe quantum dots is an important parameter for controlling resulting composites. The resulting solution is optically transparent if one component is in excess. Photoluminescence of CdTe quantum dots undergoes considerably quenching if CdTe nanocrystals are in excess and SERS spectra of BVPP absorbed on Ag colloid became stronger if Ag nanoparticles are in excess. Nevertheless, while the ratio is approximately 1, micrometer-sized solid composite is obtained with the elapse of 1h after mixing. SERS spectra for solid composite only exhibit the signals of the CdS nanocrystal which reflected that prolonged refluxing during the synthesis leads to a partial hydrolysis of the thiols and to the incorporation of the sulfur from the thiol molecules into the the growing nanoparticles to form mixed CdTe(S) nanocrystal, similar to CdTe/CdS core/shell structure. From the results, we conclude that optical properties of Ag/CdTe are dependent on the mixing ratio of both nanoparticles.

Cadmium Compounds↗