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PubMed2000

[Infrared and Raman spectra studies on isomultinuclear organometallic carbyne compounds].

The infrared and Raman spectra of five isomultinuclear organometallic carbyne compounds were studied. The results show that the introduction of N atom from TMEDA or P atom from DPPE to W atom (both N and P are strong sigma-donor and weak pi-acceptor) will decrease the bonding intensity of W identical to C. The pressure tunning IR and Raman spectra of compound III indicate the presence of pressure-induced phase-transition near 20 kbar in it. There are two effects on the nu (W identical to C) of this compound with increasing pressure: the normal increasing the nu (W identical to C) wavenumber due to the shorting W identical to C bond and increasing the W-CO pi backbonding to decrease the nu (W identical to C) wavenumber.

Carbamates↗
PubMed2001

[The design and evaluation of horizontal pipe mini-flame atomization and ionization synchronous detector in GC/AAS].

Gas chromatography/atomic absorption spectroscopy(GC/AAS) is a good method for the species analysis of organometallic compounds. But the traditional atomizers are not very suitable for this technology and all of them response only to one kind of signal--the concentration of the metallic atoms of the ground state. They can not give any information about the organic group of organometallic compounds and organic compounds which coexist with the former. For GC/AAS we want to design and manufacture a new kind of detector which is much more sensitive and has a much smaller dead volume and will sensitively and synchronously response to the atomization signal of organometallic compound and ionization signal of organic compound. The authors have noticed that the atomization of organometallic compound and ionization of organic compound have been existing in the same hydrogen flame. The question is how to gain and exchange and output the two signals which are completely different in characters. For this purpose we designed and manufactured a new type of horizontal pipe mini-flame atomization and ionization synchronous detector. The key part is a T type glass tube (80 mm x 13 mm x 10 mm i.d.) which covers horizontally on the jet of the mini-flame atomizer and a long pipe stainless steel collector (70 mm x 9.5 mm o.d. x 9 mm i.d.) is tightly inserted in the tube. The light beam of the hollow cathode lamp passes through the hydrogen flame along the axial center of the glass tube and the ground state metallic atoms in the flame diffuses to both ends of the tube along the axial center of the glass tube too. This process enriches the depth of the light absorption and then increases the sensitivity of atomization. At the same time the long pipe collector can enrich the collection efficiency of the ionization and increases the sensitivity and widens the linear range. So the detector can synchronously and sensitively detect the organometallic and organic compounds. The detection limit for atomization of the organometallic compound(diethylmercury) is 2.5 x 10(-11) g.s-1 and for ionization of the organic compound (benzene) is 1.0 x 10(-11) g.s-1. The linear range is 7.0 x 10(2) for atomization of diethylmercury (r = 0.9989) and 2.5 x 10(5) for ionization of benzene (r = 0.9992). The selectivity of the detector to the organic solvent under the optimum operating condition of atomization is 10(4)-10(7). The relative standard deviation (RSD, n = 11) of the peak area in the optimum operating conditions of atomization for the organometallic compound (diethylmercury) and of ionization for the organic compound (benzene) is 1.8% and 1.5% respectively. Under the same operating condition, the atomization and the ionization can not reach the optimum performance at the same time. If the atomization is in the optimum performance state, the performance for ionization is like a chromatographic thermal conductivity detector (TCD). The optimum performance of the atomization and ionization can be quickly adjusted by changing the flow rates of the corresponding gases such as H2, N2 and air.

Benzene↗
PubMed1978

Mechanisms for the biomethylation of metals and metalloids.

The case of methylmercury pollution has demonstrated the profound importance of understanding biologically mediated transformation reactions that yield organometallic compounds with a high potential for bioaccumulation and toxicity. Toxic elements that form organometallic compounds, especially the metal-alkyls (e.g., methylmercury), deserve special concern. Most metal-alkyls are poisonous to the central nervous systems of higher organisms, and these compounds do accumulate in cells. Metal-alkyls that are stable in water, and that have been reported to be synthesized biologically, can be formed from the following toxic elements: Hg, Sn, As, Se, Te, Pd, Au, Tl and Pb. In this report we present details of the mechanisms for biological methylation of certain metals and metalloids with special emphasis on those elements that are widely dispersed in the biosphere. In addition we present preliminary results on the use of flourescence quenching techniques to determine cellular diffusion rates and partition coefficients for methylmercuric chloride.

Alkylmercury Compounds↗
PubMed1997

Detection of toxic organometallic complexes in wastewaters using algal assays.

Chlorella (a unicellular green alga) and Cladophora (a filamentous alga) were used in algal assays to identify the presence and toxicity of organometallic complexes in four industrial wastewaters. Toxicities of inorganic Pb and organometallic compounds (trimethyl, tetramethyl and tetraethyl leads, cacodylic acid and Cu-picolinate) were examined, using algal cells grown in 10% BBM solution. Inorganic Pb and organometallic compounds altered the fine structure of Chlorella cells in a distinguishable manner. X-ray microanalysis revealed that organometallic compounds accumulated in the neutral lipids of Cladophora cells. By applying the above techniques to the wastewater assays, two of the four wastewaters tested were found to contain organometallic complexes. Wastewater from a chemical company contained only traces of organo-Cu, but one mining effluent contained significant quantities of organo-Cu and organo-Pb, and traces of organo-Cr and organo-Tl (thallium). These studies suggest that X-ray microanalysis of algae may be a useful tool in identifying aquatic systems contaminated with metals and organometallic compounds.

Chlorella↗
PubMed2003

Liquid chromatography-mass spectrometry and strategies for trace-level analysis of polar organic pollutants.

Liquid chromatography-mass spectrometry using atmospheric pressure ionization (LC-API-MS) has drastically changed the analytical methods used to detect polar pollutants in water. The present status of application of this technique to organic water constituents is reviewed. The selection of the appropriate LC conditions, whether reversed-phase liquid chromatography, ion-pair chromatography, capillary electrophoresis or ion chromatography, and of the most sensitive ionization mode, electrospray ionization (ESI) or atmospheric pressure chemical ionization (APCI), depends upon the polarity and acidity of the analytes. Strongly acidic compounds such as aromatic sulfonates, sulfonated dyes, haloacetic acids, linear alkylbenzene sulfonates, aliphatic sulfonates and sulfates and complexing agents, weakly acidic compounds such as carboxylates and phenols, neutral compound classes, namely alkylphenol ethoxylates, alcohol ethoxylates and polycyclic aromatic hydrocarbons and the basic toxins, quaternary ammonium compounds and organometallic compounds are considered. The selection of the mass spectrometer depends upon the analytical task: triple-quadrupole mass spectrometers are highly suited for sensitive quantitation and for qualitative analyses, ion traps are especially suited for structure elucidation, whereas time-of-flight mass spectrometers and quadrupole time-of-flight mass spectrometers with their higher mass resolution are ideal for the determination of molecular formulas of unknown compounds and for screening purposes. While large steps have already been made, future efforts with respect to water analysis may be directed at fine-tuning the methodical arsenal for increased sensitivity and selectivity and to extend LC-MS application to transformation products.

Chromatography, Liquid↗
PubMed2002

Antiproliferative and cytotoxic effect of a novel organotin compound on mammalian cells both in vitro and in vivo.

Organotin compounds are organometallic compounds showing various toxicological properties. Several organotin compounds also showed an antineoplastic effect. However, their relative mutagenic potential is not well established. In this study Et(2)SnCl(2).L [L=N-(2-pyridylmethylene)-4-toluidine] (OTC) has been subjected to investigation for its cytotoxic effect in mouse bone marrow cells (BMCs) and human peripheral blood lymphocyte cells (HPBLs). The Sn [bond] N bond in OTC is 2.46A which is greater than 2.39A and therefore, a better formation of tin-DNA complex can be expected. The present data indicate that OTC induced significant delay in cell kinetics and sister chromatid exchanges (SCEs) in both BMCs and HPBLs, whereas, induction of chromosome aberrations was found only in HPBLs. The presence of buthionine sulfoximine (BSO) modulated cellular sensitivity towards OTC in both cell systems. It may be inferred that the OTC could bind on DNA more easily owing to its structural advantage and this may explain the induction of DNA damage and the delay in cell proliferation. Since the cytotoxic effect of OTC is more in glutathione depleted cells, the concentration of OTC may be reduced to get an antitumour effect in GSH-depleted cells and thus minimizes its toxic side effect.

Animals↗
PubMed1996

Structure Determination of a Complex Tubular Uranyl Phenylphosphonate, (UO(2))(3)(HO(3)PC(6)H(5))(2)(O(3)PC(6)H(5))(2).H(2)O, from Conventional X-ray Powder Diffraction Data.

The three-dimensional structure of a complex tubular uranyl phosphonate, (UO(2))(3)(HO(3)PC(6)H(5))(2)(O(3)PC(6)H(5))(2).H(2)O, was determined ab initio from laboratory X-ray powder diffraction data and refined by the Rietveld method. The crystals belong to the space group P2(1)2(1)2(1), with a = 17.1966(2) Å, b = 7.2125(2) Å, c = 27.8282(4) Å, and Z = 4. The structure consists of three independent uranium atoms, among which two are seven-coordinated and the third is eight-coordinated. These metal atoms are connected by four different phosphonate groups to form a one-dimensional channel structure along the b axis. The phenyl groups are arranged on the outer periphery of the channels, and their stacking forces keep the channels intact in the lattice. The determination of this structure which contains 50 non-hydrogen atoms in the asymmetric unit, from conventional X-ray powder data, represents significant progress in the application of powder techniques to structure solution of complex inorganic compounds, including organometallic compounds.

Journal Article↗
PubMed2002

Gold(III) complexes with bipyridyl ligands: solution chemistry, cytotoxicity, and DNA binding properties.

Gold(III) compounds generally exhibit significant cytotoxic effects on cancer cell lines and are of potential interest as antitumor drugs. We report here on the solution chemistry, the cytotoxicity, and the DNA binding properties of two new bipyridyl gold(III) compounds: [Au(bipy)(OH)(2)][PF(6)] (1) and the organometallic compound [Au(bipy(c)-H)(OH)][PF(6)] (2) (bipy(c) = 6-(1,1-dimethylbenzyl)-2,2'-bipyridine). Both compounds are sufficiently soluble, and stable for hours, within a physiological buffer at 37 degrees C; [Au(bipy)(OH)(2)][PF(6)], at variance with [Au(bipy(c)-H)(OH)][PF(6)], is quickly and quantitatively reduced by ascorbate. Both compounds showed relevant cytotoxic effects toward the A2780S, A2780R, and SKOV3 tumor cell lines; lower effects were detected on the CCRF-CEM/S and CCRF-CEM/R lines. In most cases the mechanisms of resistance to CDDP are only marginally effective against these gold(III) complexes. The interactions of [Au(bipy)(OH)(2)][PF(6)] and [Au(bipy(c)-H)(OH)][PF(6)] with calf thymus DNA were investigated in vitro by various techniques to establish whether DNA represents a primary target for these compounds. Addition of saturating amounts of DNA did not affect appreciably the visible spectra of these gold(III) complexes. Some slight modifications of the CD spectra of calf thymus DNA and of the DNA melting parameters were observed; in any case, ultrafiltration experiments showed that binding of these gold(III) complexes to DNA is weak and reversible. The mechanistic implications of these findings are discussed.

2,2'-Dipyridyl↗
PubMed2004

[Benzylbis(dimethylamino)methylsilyl-kappa2C,N](N,N,N',N'-tetramethylethylenediamine-kappa2N,N)lithium(I).

The title compound, [Li(C12H21NSi)(C6H16N2)], is an intermediate in the synthesis of the corresponding organometallic compounds. The molecule has an unusual C-Si-N-Li four-membered heterocycle which adopts a folded conformation, with the coordination around the Li, N, C and Si atoms being distorted tetrahedral. Its structure is strongly supported by 1H NMR, 13C NMR and 13C-1H correlation spectra. The compound has potential for application in the synthesis of other novel organometallic compounds.

Journal Article↗
PubMed1997

Bioorganometallic chemistry--synthesis and antitumor activity of cobalt carbonyl complexes.

The interaction of organometallic compounds with biological systems, generally called bioorganometallic chemistry, is receiving increasing interest. We present the first part of our studies concerning the biological activity of organometallic compounds. Several alkyne-cobalt carbonyl complexes inhibited the growth of human melanoma and lung carcinoma cell lines. They are more active than uncomplexed dicobalt octacarbonyl, cobalt chloride, or the free ligand. A significant difference in potency towards the lung carcinoma cell line was observed among the cobalt complexes, indicating that the complexed ligand may influence cytotoxic activity. These results suggest that further exploratory work with such cobalt-alkyne complexes is warranted.

Adenocarcinoma↗
PubMed2002

Mechanochemical assembly of hydrogen bonded organic-organometallic solid compounds.

Solvent-free reactions with molecular systems have been exploited to prepare hybrid organic-organometallic solids: grinding of the complex [Fe(eta 5-C5H4COOH)2] with solid bases B generates quantitatively the corresponding hydrogen bonded salts [Fe(eta 5-C5H4COOH)(eta 5-C5H4COO)][HB] (B = 1,4-diazabicyclo[2.2.2]octane, 1,4-phenylenediamine); gas-solid reactions are also possible with volatile bases.

Journal Article↗
PubMed2006

Characterization of various analytes using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and 2-[(2E)-3-(4-tert-butylphenyl)-2-methylprop-2-enylidene]malononitrile matrix.

2-[(2E)-3-(4-tert-Butylphenyl)-2-methylprop-2-enylidene]malononitrile (DCTB) is a nonpolar, aprotic matrix and was used in the analysis of a variety of compounds by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). The classes of compounds include coordination compounds, organometallics, conjugated organic compounds (including porphyrins and phthalocyanines), carbohydrates, calixarenes, and macrocycles. For some samples, comparisons are made with spectra acquired with the use of 1,8,9-trihydroxyanthracene (dithranol), 2,5-dihydroxybenzoic acid, and 2,4,6-trihydroxyacetophenone matrixes. Traditionally, the majority of these compounds would have been analyzed by fast-atom bombardment (FAB), liquid secondary ion mass spectrometry (LSIMS), or electrospray techniques, but this work shows that MALDI-TOFMS using DCTB has advantages over these techniques, particularly FAB and LSIMS. Certain limitations of DCTB are noted, for example, in the analysis of water-soluble compounds such as peptides, proteins, and oligonucleotides, and good working practices for the use of the matrix are also outlined.

Journal Article↗
PubMed1999

Organotin compounds decrease in vitro survival, proliferation and differentiation of normal human B lymphocytes.

Organotin compounds (OTC) are organometallic compounds with vast industrial and agriculture applications that give rise to ubiquitous environmental contamination. OTC are immunotoxic, but most studies have been performed in rodents and almost exclusively focused on T cell immunity. Humans can be exposed to OTC by inhalation, absorption, and consumption of contaminated food and water. To analyse the effects of OTC in human immune tissue, we isolated B cells from tonsils and exposed them to five OTC at various concentrations, during in vitro culture. Non-stimulated B cells were killed by 100 nM of all tested OTC after 8 h in vitro culture, under sub-optimal conditions, except TET. OTC also decreased the proliferation of tonsillar B lymphocytes stimulated with Staphylococcus aureus Cowan 1 (SAC) and IL-2, when present at 100 nM and higher concentrations. IgM secretion was reduced in stimulated cell cultures exposed to 100 nM dibutyltin chloride (DBT). Accordingly, increased phosphatidylserine exposure demonstrated that 100 nM TPT and DBT induced B cells to die by apoptosis. These data indicate that human B cells are diminished in their capacity to survive, proliferate and differentiate in the presence of OTC in vitro.

Apoptosis↗
PubMed1985

Microcolumn high pressure liquid chromatography with a glass-frit nebulizer interface for plasma emission detection.

Microcolumn high pressure liquid chromatography (micro-HPLC) is rapidly gaining recognition as a practical separation tool for organometallic compounds. The use of the inductively coupled plasma (ICP) as a detector for micro-HPLC is studied. Several miniaturized glass-frit nebulizers are investigated as interfaces between the output of the microbore column and the ICP torch. Their performance with aqueous and methanolic solutions is evaluated by direct nebulization and flow injection analysis. The most efficient of these nebulizers is used in the micro-HPLC/ICP study of some Cd, Pb, and Zn organometallic compounds. Detection limits of 1.92 ng of Pb for tetramethyllead and 5.01 ng of Pb for tetraethyllead are obtained and compared with regular HPLC/ICP of these same compounds. Approximately equivalent detection limits were obtained when using a microwave induced plasma as an alternate plasma source.

Chromatography, High Pressure Liquid↗
PubMed2001

Sample treatment in chromatography-based speciation of organometallic pollutants.

Speciation analysis is nowadays performed routinely in many laboratories to control the quality of the environment, food and health. Chemical speciation analyses generally include the study of different oxidation state of elements or individual organometallic compounds. The determination of the different chemical forms of elements is still an analytical challenge, since they are often unstable and concentrations in different matrices of interest are in the microg l(-1) or even in the ng l(-1) range (e.g., estuarine waters) or ng g(-1) in sediments and biological tissues. For this reason, sensitive and selective analytical atomic techniques are being used as available detectors for speciation, generally coupled with chromatography for the time-resolved introduction of analytes into the atomic spectrometer. The complexity of these instrumental couplings has a straightforward consequence on the duration of the analysis, but sample preparation to separate and transfer the chemical species present in the sample into a solution to be accepted readily by a chromatographic column is the more critical step of total analysis, and demands considerable operator skills and time cost. Traditionally, liquid-liquid extraction has been employed for sample treatment with serious disadvantages, such as consumption, disposal and long-term exposure to organic solvent. In addition, they are usually cumbersome and time-consuming. Therefore, the introduction of new reagents such as sodium tetraethylborate for the simultaneous derivatization of several elements has been proposed. Other possibilities are based in the implementation of techniques for efficient and accelerated isolation of species from the sample matrix. This is the case for microwave-assisted extraction, solid-phase extraction and microextraction, supercritical fluid extraction or pressurized liquid extraction, which offer new possibilities in species treatment, and the advantages of a drastic reduction of the extraction time and the embodiment into on-line flow analysis systems. This new generation of treatment techniques constitutes a good choice as fast extraction methods for feasible species-selective analysis of organometallic compounds under the picogram level, that can be used for national regulatory agencies, governmental and industrial quality control laboratories, and consequently, for manufacturers of analytical instrumentation.

Chromatography↗
PubMed2001

Vanadocenes as potent anti-proliferative agents disrupting mitotic spindle formation in cancer cells.

We present experimental data which establish the organometallic compounds vanadocene dichloride (VDC) and vanadocene acetylacetonate (VDacac) as potent anti-proliferative agents. We first examined the effects of VDC and VDacac on the rapid embryonic cell division and development of Zebrafish. Both compounds were capable of causing cell division block at the 8-16 cell stage of embryonic development followed by total cell fusion and developmental arrest. We next examined the effect of VDC and VDacac on proliferation of human breast cancer and glioblastoma cell lines using MTT assays. VDC inhibited the proliferation of the breast cancer cell line BT-20 as well as the glioblastoma cell line U373 in a concentration-dependent fashion with IC50 values of 11.0, 14.9 and 18.6 microM, respectively. VDacac inhibited cellular proliferation with IC50 values of 9.1, 26.9 and 35.5 microM, respectively. Whereas in vehicle-treated control cancer cells mitotic spindles were organized as a bipolar microtubule array and the DNA was organized on a metaphase plate, vanadocene-treated cancer cells had aberrant monopolar mitotic structures where microtubules were detected only on one side of the chromosomes and the chromosomes were arranged in a circular pattern. In contrast to control cells which showed a single focus of gamma-tubulin at each pole of the bipolar mitotic spindle, VDC- or VDacac-treated cells had two foci of gamma-tubulin on the same side of the chromosomes resulting in a broad centrosome at one pole. All monopolar spindles examined had two foci of gamma-tubulin labeling consistent with a mechanism in which the centrosomes duplicate but do not separate properly to form a bipolar spindle. These results provide unprecedented evidence that organometallic compounds can block cell division in human cancer cells by disrupting bipolar spindle formation. In accordance with these results vanadocene treatment caused an arrest at the G2/M phase of the cell cycle. This unique mechanism of anti-mitotic function warrants further development of vanadocene complexes as anti-cancer drugs.

Animals↗
PubMed2005

Heterometallic compounds assembled from ferrocene-containing bisthiosemicarbazone clips.

Heteropolynuclear organometallic compounds have been constructed by using the ferrocene-based ligand H(2)L, [NH(2)SCNHN=C(CH(3))(C(5)H(4))](2)Fe. Reaction of the ligand H(2)L with the cobalt(II) salt gave a tetranuclear helicate Co(2)Fe(2) (1) with two ferrocene-based clips wrapped around the two cobalt atoms. The chiral helicates recognized the neighbors with same chirality through intermolecular hydrogen bonding between the thiosemicarbazone moieties to form a one-dimensional chiral channel. Reaction of the ligand H(2)L with the cadmium(II) salt afforded a tetranuclear dimeric compound Cd(2)Fe(2) (2), with two symmetric related parts bridged through two sulfur atoms. Reaction of the ligand H(2)L with the copper(I) salt, in the presence of triethylamine, resulted in a hexanuclear compound Cu(4)Fe(2) (3) with a crownlike Cu(4)S(4) octagon similar to that of S(8) sited inside and two ferrocene-containing ligands positioned outside. Electrochemical measurements were displayed to investigate the redox communications between the ferrocene moieties through metal centers.

Cadmium↗