bluuebunny/crossref_metadata_2025_split huggingface dataset:
Decomposition of organoarsenic compounds by using a microwave oven and subsequent determination by flow injection‐hydride generation‐atomic absorption spectrometry
Authors: Le Xiao‐Chun , Cullen William R , Reimer Kenneth J 
Published: January 2005

AbstractEnvironmentally important organoarsenicals such as arsenobetaine, arsenocholine and tetramethylarsonium ion do not form volatile hydrides under the commonly used analytical conditions on treatment with borohydride and it has been difficult to determine their concentrations without further derivatization. This paper describes a rapid method which completely decomposes and oxidizes these arsenicals to arsenate by using potassium persulphate and sodium hydroxide with the aid of microwave energy. The quantitative decomposition of these species permits their determination at low nanogram levels, by hydride generation atomic absorption spectromety (HG AA). A new hydride generator which has high efficiency and minimum dead volume and therefore is suitable for flow injection analysis (FIA) is also described. A system combining flow injection analysis, online microwave oven digestion, and hydride generation followed by atomic absorption measurement, is developed. This system is capable of performing analysis at a sample throughput of 100‐120 per hour. Calibration curves were linear from 10 to 200 ng cm−3 of arsenic and the detection limit was 5 ng cm−3 for a 100‐μ injection or 0.5 ng of arsenic. All ten organoarsenic compounds studied gave arsenate as the decomposition product, which was confirmed by using molybdenum blue photometric measurement.
Determination of tributyltin oxide in coastal marine sediments and mussels by electrothermal atomic absorption spectrometry
Authors: Cardellicchio N , Geraci S , Marra C , Paterno P 
Published: January 2005

AbstractWe have devised a new method for bis(tributyltin)oxide (TBTO) determination in marine sediments and mussels. This technique involves an n‐hexane/methylene chloride mixture extraction and extract purification with a sodium hydroxide wash in order to eliminate interfering compounds. TBTO is then extracted again by nitric acid and converted into an inorganic tin species; the analysis has been effected using Zeeman graphite furnace‐atomic absorption spectrophotometry. The method detection limit for the matrices examined is 0.004 μg TBTO g−1 (wet weight) and is sufficient for the analysis in real samples. The percentage recovery of TBTO from sediments and mussels samples is higher than 85% and 95% respectively. This method has been applied to TBTO level determination in sediments and mussels (Mytilus galloprovincialis) sampled in the harbour area in Taranto, where mussel culture activities are much developed; the TBTO levels obtained in sediments and mussels were in the range 15‐47 ng g−1 (wet weight) and 11‐30 ng g−1 (wet weight) respectively. Such values are comparable with those found in other harbour areas in the Mediterranean Sea.
The synthesis and characterization of norbornylsilasesquioxanes
Authors: Hambley Trevor W , Maschmeyer Thomas , Masters Anthony F 
Published: January 2005

AbstractNorbornene reacts with trichlorosilane to generate norbornyltrichlorosilane in high yield. The slow hydrolysis of norbornyltrichlorosilane in acetone yields incompletely condensed norbornyl‐silasesquioxanes. The compound C42H70O11Si6 can be isolated from this reaction. On the basis of elemental analyses, 1H, 13C and 29Si NMR, mass spectroscopy, infrared spectroscopy, and crystallographic analysis, C42H70O11Si6 is formulated as [(C7H11)6Si6O7(OH)4], with the Si6O7 framework being composed of two perpendicular Si4O4 planes sharing an edge. [(C7H11)6Si6O7(OH)4] is a putative model of vicinal [Si(OH)]2 sites on the surface of partially dehydroxylated silica.
Speciation of some triphenyltin compounds in estuarine sediments using mössbauer spectroscopy
Authors: Lucero Rosemarie A , Otieno Monicah A , May Leopold , Eng George 
Published: January 2005

AbstractThe speciation of several triphenyltin compounds, i.e. triphenyltin hydroxide, acetate, chloride and fluoride, was studied by Mössbauer spectroscopy in both anaerobic and aerobic estuarine sediments. The results indicated that triphenyltin hydroxide and acetate were converted to the triphenyltin cation, the species that interacts with the sediments. However, both triphenyltin fluoride and chloride remained in their molecular form in their interaction with the sediments.
The toxic effects of organometals on the lands cycle in HL‐60 cells
Authors: Krug H F 
Published: January 2005

AbstractThe concentration of free fatty acids within cells is mainly dependent upon the following enzyme activities: liberation by phospholipase A2 (PLA2), activation of free acids by acyl‐CoA‐synthetase and re‐esterification by lysophospholipid acyltransferase (LAT). In many cell types, especially those of the haematopeotic system, this deacylation‐reacylation cycle (‘Lands cycle’) plays an important role in the regulation of free fatty acid concentration, above all that of arachidonic acid.We have shown here that heavy‐metal compounds affect this cycle mainly at two points and thereby lead to an increase of free fatty acids. On the one hand, organometals cause an inhibition of the reacylation of lysophospholipids; and on the other, the induction of PLA2 activity produces the same result. All compounds investigated such as methylmercury chloride (MeHgCl), diethyltriethyl‐, and trimethyl‐lead chloride (Et2PbCl2, Et3PbCl, Me3PbCl) as well as trimethyltin chloride (Et3SnCl) and di‐t‐butyltin dichloride (t‐Bu2SnCl2) show at least one of these effects. In the case of Et3PbCl, the use of PLA2‐inhibitors or pertussis toxin causes a drastic decrease in the amount of arachidonic acid liberated. These experiments demonstrate that the organometallic compounds inhibit the reacylation and/or stimulate the deacylation of fatty acids that are involved in many important biological or pathological mechanisms. The results suggest that in differentiated HL‐60 cells the organometal compounds stimulate the Lands cycle by increasing the activity of the PLA2, possibly via a signal‐transduction mechanism, and this effect is intensified via an inhibition of reesterification.
Molybdenum/cobalt/sulfur clusters: Models and precursors for hydrodesulfurization (HDS) catalysts
Authors: Curtis M David 
Published: January 2005

AbstractSulfido clusters which incorporate molybdenum and a late transition metal, e.g. iron, cobalt or nickel, are readily prepared by the reactions of Cp2Mo2S4, Cp2Mo2S2(SR)2 or Cp2Mo2(CO)2(SR)2 with Fe2(CO)9, Co2(CO)8, Ni(CO)4, Cp2Ni, etc. The homogeneous reactions of the cluster Cp2Mo2Co2S3(CO)4 with thiols, thiophene, and phosphines are reviewed, as are some reactions of the clusters with metal oxide surfaces to produce heterogeneous catalysts for CO hydrogenation or hydrodesulfurization.
Studies on binuclear Schiff base derivatives having a SiOSb (V) linkage
Authors: Chaturvedi Vibhav , Tandon J P , Chaturvedi Laxmi 
Published: January 2005

AbstractSchiff base derivatives of the type Ph3SiOSb(NO)Ph3 (where NO represents the donor system of a monobasic bidentate ligand) have been synthesized. These are obtained as coloured solids; they are non‐electrolytes and monomeric in nature, and have been characterized by elemental analysis, IR and 1H NMR. Spectral studies suggest that silicon and antimony atoms are in tetra‐ and hexa‐coordinated states, respectively.
Neurotropic activity of organogermanium compounds
Authors: Lukevics E , Germane S , Ignatovich L 
Published: January 2005

AbstractNeurotropic activity of several classes of organogermanium compounds (namely germatranes, germanols, germsesquioxanes, germyladamantanes, germylamides, germylimides and germylsubstituted amines, imines and hydroxamic acids) and their synthesis are reviewed.
Preparation of amphiphilic organoiron(1+) complexes having two long‐chain alkyl groups and their molecular assemblage characteristics
Authors: Sakai Hiroshi , Toyota Takema , Fujinami Tatsuo , Sakai Shizuyoshi 
Published: January 2005

Abstract[o‐, m‐ and p‐Bis(alkylamino or alkyloxy)benzene] (cyclopentadienyl)iron(1+) hexafluorophosphates {2 and 4; [(CnH2n+1X)2C6H4](C5H5)Fe+PF6−, XNH or O} were prepared by aromatic nucleophilic substitution of the (dichlorobenzene)iron cationic complexes (1). Critical micelle concentrations of the complex chlorides (3), prepared from 2 (n=8, XNH) by anion exchange and soluble in water, gave much smaller values than those of bis(long‐chain alkyl)dimethylammonium surfactants. Furthermore, the substitution positions scarcely affected their surface activites. However, the surface pressure‐molecular area isotherm of the hexafluorophosphates (2 and 4, n=18, XNH; insoluble in water) were severely transformed by change in the substitution position of the long‐chain alkyl groups on the benzene ligand in the iron cationic complexes: the o‐substituted complex gave a molecularly assembled film by the Langmuir‐Blodgett (LB) method, but the P‐substituted one did not.
Speciation of butyltin compounds by ion chromatography coupled to electrothermal atomic absorption spectrometry
Authors: Pannier F , Dauchy X , Potin‐Gautier M , Astruc A , Astruc M 
Published: January 2005

AbstractA new method for the determination of butyltin species by ion‐exchange chromatography linked with graphite‐furnace electrothermal atomic absorption spectrometry (ETAAS) is presented. The separation is achieved on a strong cation‐exchange column with a 0.18 mol dm−3 solution of diammonium citrate at pH 6.5 with a step change to pH 4.0 in 60:40 methanol/water solvent. ETAAS detection is performed on‐line using an oxidizing matrix modifier. Mono‐, di‐ and tri‐butyltin may be determined in a single experiment with detection limits of (respectively) 0.5, 1.1 and 0.8 ng (Sn). Applications to actual samples are reported.
Polymeric organosilicon systems 14. Synthesis and some properties of alternating polymers composed of a dithienylene group and a mono‐, di‐ or tri‐silanylene unit
Authors: Ohshita Joji , Kanaya Daisuke , Ishikawa Mitsuo 
Published: January 2005

AbstractPoly[5, 5′ ‐ (dimethylsilylene) ‐ 2, 2′ ‐ dithienylene] (4a), poly[5, 5′ ‐(methylphenylsilylene)‐2, 2′ ‐dithienylene] (4b), poly[5, 5′ ‐(1, 1, 2, 2‐tetramethyldisilanylene)‐2, 2′ ‐dithienylene] (4c), poly[5, 5′‐(1, 2‐dimethyl‐1, 2‐diphenyldisilanylene)‐2, 2′ ‐dithienylene] (4d), poly[5, 5′‐(1, 2, 2, 2‐tetramethyldisilanylene)‐2, 2′‐dithienylene] (4e), and poly[5, 5′‐(1, 1, 2, 2, 3, 3 ‐ hexamethyltrisilanylene) ‐ 2, 2′ ‐dithienylene] were synthesized by dehalogenative coupling of the respective bis(2‐bromothienyl)‐ substituted mono, di‐ and tri‐silanes with magnesium in the presence of a catalytic amount of a nickel(II) complex in 16–99% yields. The polymers thus obtained are light‐yellow solids and soluble in common organic solvents. Molecular weights, Mw, of the polymers were measured and found to be 7800–35 000 by gel‐permeation chromatography relative to polystyrene standards. The photochemical properties of the polymers (4a–4d) having silylene and disilanylene units were investigated. Only poly[5, 5′‐(1, 2‐dimethyl‐1, 2‐diphenyl‐disilanylene)‐2, 2′‐dithienylene] (4d) was found to be photoactive, but the others were inactive. When the thin solid films prepared from the polymers 4a–4e by spin‐coating were exposed to antimony(V) fluoride in vacuo, the films became conducting; their conductivities were determined to be 10−2 – 10−3 S cm−1 by the four‐probe method.
Accumulation and toxic effect of organometallic compounds on algae
Authors: Huang Guolan , Bai Zhipeng , Dai Shugui , Xie Qinglan 
Published: January 2005

AbstractThis paper reports toxic effects and bioaccumulation factors of organometallic compounds, mainly organotin species, on algae. We selected two species of microalgae as test algae: one was Scenedesmus obliquus as a representative of fresh‐water algae, the other Dunaliella salina and Dunaliella viridis, to represent commonly mixed algae which exist abundantly in Tianjin Harbor, People's Republic of China. For comparison, Chlorella vulgaris was also used in this study. The toxic effect of ten organometallic compounds on the freshwater alga, S. obliquus, was investigated. The ten compounds were (as chlorides) tributyltin (TBT); triphenyltin (TPT); trimethyltin (TMT); dibutyltin (DBT); diphenyltin (DPT); dimethyltin (DMT); trimethyl‐lead acetate (TML); dimethyl‐arsine (DMA) and two new mixed‐alkyltin pesticides, dicyclohexylmethylitin acetate (Cy2MTA) and dicyclohexylmethyltin isobutyrate (Cy2MTB). The order of toxicity of these compounds in fresh‐water algae, S. obliquus, was TBT>TPT>DBT> Cy2MTA=TML> Cy2MTB>DPT>TMT>DMA>DMT, according to 96 h EC50 values attained. The ten toxicants were divided into three groups according to the sequence of their toxicities; (a) TBT, TPT; (b) DBT, Cy2MTA, TML, Cy2MTB; (c) DPT, TMT, DMA, DMT. In each group the EC50 values of each compound were quite similar. The difference of EC50 values between two vicinal groups was approximately one order of magnitude. The bioconcentration factor (BCF) of TBT and TPT compared with water in the freshwater alga S. obliquus was >3.32 × 105 and 1.14 × 105, respectively. The BCF of the marine mixed algae was >3.48 × 105. The marine microalga, Chlorella vulgaris, was adaptable to TBT at lower concentration. TBT at high concentration only inhibited the growth of S. obliquus, but it could cause chlorosis anddisintegration of D. salina and D. viridis. Resistance to toxicity of algae against TBT appears in order as follows: C. vulgaris>S. obliquus>D. salina and D. viridis. TBT was metabolized by algae to a less toxic product, DBT. The existence of algal cells accelerated the concentration reduction of TBT. The toxic mechanism of TBT was also studied.
The F1F0‐ATPase binding site of dibutyltin‐3‐hydroxyflavone: Interactions with venturicidin, oligomycin and DCCD
Authors: Griffiths David E , Usta Julnar , Tian Ya Min 
Published: January 2005

AbstractDibutyltin‐3‐hydroxyflavone bromide, Bu2Sn(of), is a fluorescent probe inhibitor of mitochondrial F1F0ATPase which reacts with and titrates a component of F0 with marked fluorescence enhancement and reacts similarly with chloroplast CF1CF0 and V‐ATPases. Its use to monitor the interactions of other F0 inhibitors (venturicidin, oligomycin, DCCD) with F1F0ATPase, both membrane‐bound and purified by solubilization is described. Trialkyltins (Bu3SnCl) back‐titrate all Bu2Sn(of) interaction sites; whereas the macrolide inhibitor venturicidin backtitrates 60±5% and oligomycin only 30±3% of Bu2Sn(of) interaction sites. Bafilomycin, the macrolide inhibitor of V‐ATPases, is inactive in this assay. DCCD acts in a different fashion from the other inhibitors. Current and potential applications of this fluorescent probe in mitochondrial bioenergetics and biogenesis are discussed.
Complexes of diorganotin(IV) dihalides with N, N′‐dimethyl‐2, 2′‐bisimidazole
Authors: Leal M P , González A Sánchez , García M E , Casas J S , Sordo J 
Published: January 2005

AbstractAdducts of N, N′ ‐dimethyl‐2, 2′‐bisimidazole (DMBIm) with diethyl‐ and dibutyl‐tin(IV) dihalides (Cl, Br) have been isolated and characterized. IR data for [SnR2X2(DMBIm)] compounds are in keeping with a six‐coordinate tin atom with DMBIm acting as a bidentate ligand, whereas in [(SnR2X2)2(DMBIm)] the tin is five‐coordinate and DMBIm acts as a bridging ligand. Measurements of conductivity in acetonitrile show the adducts to behave as non‐ionogens in this solvent. NMR data show them to undergo dissociation in CDCl3.
η3‐Allylnickel alkoxides and their use as homogeneous and heterogeneous catalysts for the dimerization of olefins
Authors: Bönnemann Helmut , Jentsch Jörg‐Dietrich 
Published: January 2005

Abstractη3‐Allylnickel alkoxides {η3‐C3H5NiOR}2 (R = Me, Et, i‐Pr, Ph, SiPh3) may be activated by gaseous boron trifluoride (BF3) to give active catalysts for the dimerization of propene in homogeneous phase. In CH2Cl2 at −20 °C catalytic turnover numbers of 5000 mol propene(mol Ni)−1h−1 were measured. The nature of the OR group influences both the catalytic activity and the oligomerization product distribution. The ratio of methylpentenes to dimethylbutenes in the dimer fraction may be controlled by the presence of additional phosphine ligands at the nickel atom.The nickel alkoxide precursor was heterogenized on alumina to give {Al2O3}–O–Ni–(η3‐C3H5). Subsequent activation using gaseous BF3 generates a powerful heterogeneous olefin dimerization catalyst which converts 50 × 103 mol propene (mol Ni)−1 at −10° to −5°C in a batchwise process and 143 × 103 mol propene (mol Ni)−1 continuously to give 75% dimers and 25% higher oligomers. The solvent‐free treatment of oxide supports, e.g. alumina or silica, with gaseous BF3 produces strong ‘solid acids’. The activated hydroxyl groups on the support surface serve as effective anchor sites for organometallic complexes to form heterogenous catalysts. By reaction of Ni(cod)2 with {Al2O3}O(BF3)H or {SiO2}O(BF3)H, η1, η2‐cyclo‐octenylnickel–O fragments may be fixed to the surface. In the absence of halogenated solvents, the resulting catalysts, e.g. {SiO2}O–(BF3)–Ni–(η1, η2‐C8H13), dimerize propene continuously at +5°C at the rate of 800 × 103 mol liquid propene (mol Ni)−1.
Speciation of selenoamino acids by on‐line HPLC ETAA spectrometry
Authors: Potin‐Gautier M , Boucharat C , Astruc A , Astruc M 
Published: January 2005

AbstractAn analytical method was developed to determine selenoamino acids in the presence of other compounds. Separation has been achieved by High Performance Liquid Chromatography (HPLC) using electrothermal atomic absorption (ETAA) spectrometry as a very sensitive and element‐specific detector. On‐line HPLC ETAAS speciation of selenocystine and selenomethionine has been studied, using a laboratory made interface. Analytical characterization of the method has been realized with standard solutions. Using a 100μl sample loop, the detection limits were calculated as 8 μgl−1 for selenomethionine and 10 μgl−1 for selenocystine with repeatability and reproducibility of 4% and 7% respectively. The method has been applied to the determination of selenoamino acids in an extract of white clover (CRM402) certified for total selenium.
Dissolved butyltins in marine waters of the netherlands three years after the ban
Authors: Ritsema R. 
Published: January 2005

AbstractIn 1990 the Dutch government banned the use of tributyltin‐containing antifouling paint for ships up to 25m long. Concentrations of dissolved (<0.45 μm) tributyltin and its degradation products di‐ and mono‐butyltin were determined in six selected marinas during three consecutive years with a frequency of five times a year, starting in 1990. The highest butyltin concentrations were found in Scharendijke located in the salt water lake Grevelingen: up to 2500 ng dm−3. In tidal‐water marinas butyltin concentrations were in the order of 50–300 ng dm−3, depending on the boating and dredging activity. In some marinas higher butyltin concentrations were found during the summer period, probably indicating the illegal use of tributyltin‐containing antifouling paints. No clear trend of decrease in dissolved tributyltin concentrations in the different marinas has been found. Due to the equilibrium between the butyltins dissolved in the water and the butyltins adsorbed onto the sediment, water concentrations will remain more or less constant.
Synthesis and structures of some diorganotin bis(hydroxamate)s
Authors: Petrosyan V. S. , Yashina N. S. , Sizova T. V. , Leonova T. V. , Aslanov L. A. , Yatsenko A. V. , Pellerito L. 
Published: January 2005

AbstractAnalysis of literature data on the antitumor activity of organotin compounds reveals that R2SnX2 and their complexes containing SnO, SnN or SnS bonds often exhibit biological activity, especially if such bonds are formed by means of intramolecular coordination. Furthermore, a wide range of biological activities, from fungicidal, bactericidal and antiseptic to psychotropic and antitumor, is found to be characteristic for some organic hydroxamic acids (N‐acylhydroxylamines). From this point of view the diorgantion bis‐hydroxamates in this paper are of particular interest as potential biologically active antitumor drugs. Di‐n‐butyltin bis(N‐methyl‐N‐p‐bromobenzoylhydroxylamine) is being screened for antitumor activity.
Metal–Nitrosyl complexes as a source of new vasodilators: Strategies derived from systematic chemistry and nitrosyl ligand reactivity
Authors: Reglinski J. , Butler A. R. , Glidewell C. 
Published: January 2005

AbstractA series of nitrosyl complexes of empirical formula Kn[M(CN)5NO], where M = V, Cr, Mn and Co and n = 3, or M = Mo and n = 4, have been prepared which are notional analogues of the widely used vasodilator sodium nitroprusside. Their reactivity towards common nucleophiles (OH−, NH2R, NHR2, HS− and RS−), acid and photolysis has been investigated to elucidate the desired properties required of new metal nitrosyls which may have some potential as new non‐cyanide‐based vasodilators.
Organometallic complexes with biological molecules II. Synthesis, solid‐state characterization and in vivo Cytotoxicity of Diorganotin(IV)chloro and Triorganotin(IV)chloro derivatives of Penicillin G
Authors: Maggio F. , Pellerito A. , Pellerito L. , Grimaudo S. , Mansueto C. , Vitturi R. 
Published: January 2005

AbstractSeveral new diorganotin(IV)chloro and triorganotin(IV)chloro penicillin G derivatives have been prepared. The isolated compounds showed 1:1 stoichiometry, with formulae R2SnClpenG and R3SnClpenGNa, respectively (penG− = penicillin G− = 4‐ thia ‐ 1 ‐ azabicyclo[3.2.0]heptane‐2‐carboxylate, 3,3‐dimethyl‐7‐oxo‐6‐(2‐phenylacet‐amido) anion; R = Me, Bu, Ph). The coordination environment around the the tin(IV) atom, in all of the complexes, was trigonal bipyramidal. Penicillin G behaved as a monoanionic, bismonodentate ligand in R2SnClpenG through the β‐lactamic carbonyl and unidentate ester‐type carboxylate anion, and as unidentate through the β‐lactamic carbonyl in R3SnClpenGNa, as inferred on the basis of IR spectra.The rationalization of the Mössbauer parameter nuclear quadrupole splitting, ΔE (mm s−1), according to the point‐charge model formalism, supported such an hypothesis.The partial atomic charges on tin atoms, QSn, calculated for all the diorganotin(IV)chloropenG and triorganotin(IV)chloropenGNa compounds by the CHELEQ program, correlated well with the experimental 119Sn Mössbauer parameter isomer shift, δ (mm s−1). The δ/QSn data for diorganotin(IV)chloropenG and for triorganotin(IV)‐chloropenGNa dervatives have been correlated with the δ/QSn values of triorganotin(IV) halide, cyanide, thiocyanate and cyanate compounds, whose trigonal bipyramidal polymeric structure has been well established.Finally, the biological activity of diorganotin(IV)chloropenG and triorganotin(IV)chloropenGNa derivatives has been tested using Ciona intestinalis fertilized eggs at different stages of development.