bluuebunny/crossref_metadata_2025 huggingface dataset:
An analysis of mutual assistance
Authors: Levine Murray
Published: January 2005

Conclusion

Why should community psychology be interested in mutual assistance? Mutual assistance organizations represent not an alternative to professional care by an addition to resources in the community of a kind that makes for a more competent community (Iscoe, 1974). Mutual assistance also reflects the values of empowerment that many community psychologists accept as primary (Rappaport, 1981). For those persons who suffer with conditions that may be attributed to oppressive social environments, there is no alternative to collective political and social action to produce change. The developing mutual assistance movement provides an unparalleled opportunity to enhance our understanding of the meaning and significance of social support and the conditions under which people change. Those of us in the field have every reason to embrace this movement for it is truly in keeping with the vision of community psychology.
The effect of role change on intellectual ability and on the ability self‐concept in Chinese children
Authors: Dewei Li
Published: January 2005

Conclusions

According to the findings of the present study, the following conclusions are warranted:

1. The ability self‐concept of Chinese schoolchildren was significantly enhanced by the role‐changing procedure. Therefore, schools may be able to establish positive situations involving a change in the children's role as a means for improving children's ability self‐concepts.

2. The children's motives for achievement and their language abilities were improved by the role‐change procedure.
Social networks and social competence: Exploring the effects of early adolescent friendships
Authors: Cauce Ana Mari
Published: January 2005

Conclusions

Perhaps the main significance of this work was in its methodological contributions. Most noteworthy were its attempts to expand network analysis beyond the examination of supportive functions, the use of a more objective measure of social support, and the use of a multivariate hierarchical strategy of analysis.

This study obtained correlations between social network variables and social competence indices that were highly suggestive. However, it is important to keep in mind that the sample under investigation was fairly small and relatively homogeneous with respect to ethnicity, social class, and even values. Whether the exact nature of these relationships will generalize to different samples remains an empirical question. In fact, one would suppose that some of the results would be quite different for a population that does not highly value school. Further research, ideally longitudinal in nature, is sorely needed to address some of the issues raised by this study, both in terms of the social support/network literature and the possibly changing characteristics of minority children and their social environments as they move from preadolescence to adolescence.
Effects of inorganic and organic lead compounds on chromosomal length in human lymphocytes
Authors: Andersen Ole , Grandjean Philippe
Published: January 2005

In vitro exposure of human lymphocyte cultures to spindle inhibitors reduce the average chromosome length1,2. In this report chromosome length measurements were used for indirect but quantitative evaluation of the effects of inorganic and organic lead compounds on spindle function. The data indicate that organic compounds are much more powerful spindle inhibitors than inorganic lead compounds, almost as potent as colchicine. Occupational exposure to organic lead compounds may result in partial spindle inhibition, leading to a high probability of nondisjunction.
A novel flow process for metal and ore solubilization by aqueous methyl iodide
Authors: Thayer John S , Olson Gregory J , Brinckman Frederick E
Published: January 2005

Aqueous solutions of methyl iodide (CH3I) react with metal ores and with metals, causing them to dissolve in water. This dissolution has been investigated in both static extraction and flow systems. Aqueous concentrations of metals are enhanced anywhere from 3‐ to 242‐fold. The proposed mechanism involves electrophilic attack on the solid surface, thereby breaking the linkages binding the metal to the solid lattice and causing dissolution. Because biogenic sources constitute a major component of global CH3I flux, prospects for related polyfunctional algal haloorganics as aqueous ore or metal solubilizers are noted.
Studies of the degradation of organotin stabilizers in poly(vinyl chloride) during gamma irradiation
Authors: Allen David W , Brooks John S , Unwin John , McGuinness John D
Published: January 2005

Organotin stabilizers of the type Bu2SnX2 (X = SCH2CO2C8H17 or O2CCHCHCO2C8H17) present in poly(vinyl chloride) (PVC) and subjected to varying doses of gamma irradiation in the range 1–200 kGy (0.1–20 Mrad) are shown to suffer degradation with dealkylation to form monobutyltin trichloride and tin(IV) chloride, which have been characterized by a subsequent alkylation procedure followed by gas chromatographic analysis. The extent of degradation of the stabilizers on prolonged gamma irradiation is much more severe than during thermal degradation leading to comparable blackening of the polymer.
The acute toxicity of tri‐n‐butyltin taurocholate
Authors: Sherman Larry R , Soma Denise M , Thoman Charles J
Published: January 2005

The acute toxicity for tri‐n‐butyltin taurocholate (TBT‐TA), a newly synthesized organotin steroid, was determined using Long Evans rats. The organotin compound was suspended in corn oil and administered by gavage using standard techniques. The TBT‐TA exhibited a taurocholic acid toxicity at 24 h and a tributyltin toxicity at three days. The LD50 values were 611 and 384 mg kg−1 respectively. The dead rats exhibited distended stomachs, enlarged cecums, and lesions in the gastrointestinal tract. The toxicity is similar to that observed with other trialkyltin compounds.
Quaternary onium chlorometallates as hydrosilylation catalysts
Authors: Lovel I , Goldberg Yu , Shymanska M , Lukevics E
Published: January 2005

Sixteen triethylbenzylammonium chlorometallates [Et3 NCH 2Ph][MCIn]m− (M= transition metal, m= 1–3, n= 3–6) and nine anchored ionic metal complexes [℗–CH2PBu3][MCIn]m− derived from ‘polymer‐bound tributylmethylphosphonium chloride’ have been prepared. All the complexes were studied as catalysts in the hydrosilylation of phenylacetylene with triethylsilane. The homogeneous RhIII, PtIV, IrIII, CuII, ZnII, FeIII and anchored PtIV, RhIII, OsIV complexes were found to be active in this reaction. The regio‐ and stereoselectivity of the following catalyst types is determined by the metal atom involved, being a weak function of the chemical environment; neutral chloride (MCln–m); acid (H2MCl6); salt containing the lipophilic organic cation ([Et3NCH2Ph][MCln]m−); polymer‐supported metallate anion ([℗–CH2PBu3] [MCln]m−).
Organoelement derivatives of steroids: Synthesis and structural features of organosilicon, ‐tin and ‐lead derivatives of cholesterol and desoxycholic acid
Authors: Saxena A , Huber F , Pellerito L , Girasolo A
Published: January 2005

Some organo‐Main‐Group‐IV‐element compounds of steroids of the type R3M(COL), R2Sn(COL)2 and (R3M)2(HDCA) (where R = Me or Ph; M = Si, Sn and Pb; HCOL = cholest‐5‐en‐3β‐ol; H3DCA = 3α, 12α‐dihydroxy‐5β‐cholan‐24‐oic acid), have been synthesized. The structures of these compounds have been investigated by vibrational, mass, NMR (1H, 13C, 29Si, 119Sn and 207Pb) and 119Sn Mössbauer spectroscopy. For Me3Sn(COL) both in solution and in the solid state an associated structure with distorted trigonal bipyramidal geometry around tin and three‐coordinated oxygen atoms is postulated. Discrete tetrahedral geometries are assigned to Ph3M(COL) complexes and to R2Sn(COL)2 complexes in solution. The latter compounds probably have an associated distorted trigonal bipyramidal structure in the solid state. The complexes (Ph3M)2(HDCA) also have tetrahedral geometries around the central atoms M in solution, but for (Ph3Sn)2(HDCA) a polymeric structure with both tin atoms pentacoordinated in the solid state is proposed.
Methylation of inorganic arsenic by arsenic‐tolerant freshwater algae
Authors: Maeda Shigeru , Wada Hiroshi , Kumeda Kosuke , Onoue Miyuki , Ohki Akira , Higashi Shiro , Takeshita Toshio
Published: January 2005

Five arsenic‐resistant freshwater algae which had been isolated from an arsenic‐polluted environment were studied for the biotransformation of arsenic compounds accumulated by them from the aqueous phase. The algal cells bioaccumulating arsenic were digested by 2 mol dm−3 NaOH at 95°C, the AsC bonds except for AsCH3 were cleaved by the treatment and the methylated arsenic compounds were reduced to the corresponding arsines by sodium borohydride (hydride generation). The arsines were chromatographically separated on the basis of their boiling‐point difference and determined by atomic absorption spectrophotometry.

Methylated arsenic compounds were found in all algal cells. The predominant arsenic species in the cells, however, were non‐methylated arsenic compounds which were mainly present in the residue of a chloroform–methanol extract. The non‐methylated arsenic compounds were found to be not present in the free inorganic arsenic substrate and to be bound strongly with proteins or polysaccharides in the cells. Methylated arsenic compounds were found mainly in the lipid‐soluble fractions and the major form was a dimethylarsenic compound. Trimethyl‐ and monomethyl‐arsenic compounds were detected but at very low level. The dimethylarsinic acid was not present in the free form in the lipid‐soluble fraction and should be bound with a lipid molecule.

It was also found that the accumulation of arsenic by Nostoc occurred only in living cells.
Dehydrogenative condensation of monohydrosilanes yielding disilanes in the presence of platinum complex catalysts
Authors: Tanaka Masato , Kobayashi Toshi‐Aki , Hayashi Teruyuki , Sakakura Toshiyasu
Published: January 2005

Dimethylphenylsilane was catalytically dehydrogenated and condensed in the presence of platinum complexes to give 1,1,2,2‐tetramethyl‐1,2‐diphenyl‐disilane.
The toxicity of alkyllead compounds to Scrobicularia plana (Da Costa)
Authors: Marshall S J , Jarvie A W P
Published: January 2005

Conventional (whole animal) toxicity tests were made with Scrobicularia plana (Da Costa), an infaunal estuarine bivalve, and compared with the responses recorded from siphonal preparations. Exposure of Scrobicularia to low concentrations of triethyllead chloride and trimethyllead chloride, for 35 and 60 days respectively, produced typical response curves. However, mortality had not become asymptotic with time at lower concentrations, suggesting further mortality with increased exposure time. An approximate incipient lethal concentration was predicted.

A siphonal preparation technique with isolated and in‐situ inhalent siphons of Scrobicularia was used to estimate the lowest effect concentrations of alkyllead compounds. Response to alkyllead was indicated by contraction of the siphon, recorded via an isotonic transducer. Trialkyllead compounds were more toxic than the respective dialkylleads and inorganic lead. Toxicity of trialklleads and inorganic lead. Toxicity of trialkylleads increased with alkyl chain length. Pure tetraethyllead did not cause any siphonal contraction even when applied directly to the preparation. It was concluded that tetraethyllead has a low toxicity or is non‐toxic in pure form.
Optically active alkylbipyridines as chiral ligands in asymmetric catalysis. Synthesis of 2‐(2′‐pyridyl)‐5,6,7,8‐tetrahydro‐8,9,9‐trimethyl‐5,8‐methanoquinoline and rhodium‐promoted asymmetric transfer hydrogenation of acetophenone
Authors: Gladiali Serafino , Chelucci Giorgio , Soccolini Franco , Delogu Giovanna
Published: January 2005

The title compound, a new chiral alkyl 2,2′‐ bipyridine containing a rigid alkyl framework, can be prepared through a six‐step reaction sequence from (+)‐camphor. Coordination of the new ligand to rhodium(I) procatalysts occurs with difficulty and the resulting species display a very low stereoselectivity in the catalytic transfer hydrogenation of acetophenone.
Distribution of arsenic in the natural environment with emphasis on rocks and soils
Authors: Tanaka Takeshi
Published: January 2005

Arsenic is ubiquitous in the environment. Although the average arsenic concentrations in rocks (∼2 mg kg−1), soils (∼2 mg kg−1), freshwater (∼1 m̈g dm−3), seawater (∼2 m̈g dm−3) and organisms is generally low, high arsenic concentrations in limited areas are not uncommon. Whereas terrestrial organisms appear not to accumulate arsenic, marine organisms effectively concentrate arsenic to levels thousand of times higher than in ocean waters. The geochemical cycle and mineralogy of arsenic are reviewed with some emphasis towards Japanese locations and arsenic concentrations (averages, ranges) found in samples from the lithosphere, pedosphere, hydrosphere and biosphere are tabulated and discussed.
Arsenic compounds in marine and terrestrial organisms: Analytical, chemical and biochemical aspects
Authors: Irgolic Kurt J.
Published: January 2005

Arsenic has a reputation as a poison, because arsenic trioxide was used during medieval times as an agent for murder. Lingering memories of these events make any arsenic‐containing material suspect. Toxicity is a property of a specific compound and varies with the composition and structure of compounds. Developments in analytical methodology made it possible not only to determine total arsenic in a variety of matrices but also arsenic compounds. Knowledge about the arsenic cycle in marine systems has expanded considerably during the past decade. The marine arsenic cycle appears to be more complex than the cycle in the terrestrial environment. More attention must be given to the minor arsenic‐containing compounds detected in organisms and experiments should be undertaken that provide information about the biochemical pathways used for the transformation of arsenic compounds.
Arsenic accumulation by arsenic‐tolerant freshwater blue‐green alga (Phormidium sp.)
Authors: Maeda Shigeru , Fujita Saori , Ohki Akira , Yoshifuku Isami , Higashi Shiro , Takeshita Toshio
Published: January 2005

Accumulation, biomethylation and excretion of arsenic by the arsenic‐tolerant freshwater blue–green alga, Phormidium sp., which had been isolated from an arsenic‐polluted environment, were investigated.

The cellular growth curves were in fair agreement with a ‘logistic curve’ equation. The growth increased with an increase in the surrounding arsenic concentration up to 100 m̈g g−1. The cells survived even at 7000 m̈g g−1. The arsenic concentration of the cells increased with an increase of the surrounding arsenic concentration up to 7000 m̈g g−1. Phosphorus concentrations in the medium affected the growth and arsenic accumulation. No arsenic was accumulated by cells killed by ethanol.

The arsenic was methylated to the extent of 3.2% of the total arsenic accumulated. When the cells were transferred into an arsenic‐free medium, 85% of the arsenic accumulated was excreted; 58% of the excreted arsenic was in methylated form implying extensive methylation in the arsenic‐free medium.
Acute toxicity and rapid excretion in urine of tetramethylarsonium salts found in some marine animals
Authors: Shiomi Kazuo , Horiguchi Yoshiya , Kaise Toshikazu
Published: January 2005

Acute toxicity in mice, and excretion in their urine, of tetramethylarsonium salts which are arsenic compounds found in some marine animals, were examined using synthetic tetramethylarsonium iodide. The oral, intraperitoneal and intravenous LD50 values of tetramethylarsonium iodide [(CH3)4As+I−] were determined to be 890, 175 and 82 mg kg−1, respectively. When sublethal doses of tetramethylarsonium iodide were orally administered to mice, 53–58% of the arsenic administered was recovered in urine after 6 h and 65–81% after 72 h. High‐performance liquid chromatography–inductively coupled plasma (HPLC–ICP) and fast atom bombardment mass spectrometric (FAB MS) analyses revealed that a tetramethylarsonium salt was the only arsenic compound excreted in urine. These results suggested that the major part of orally administered tetramethylarsonium iodide was absorbed from the gastrointestinal tract in mice and then rapidly excreted in urine without biotransformation.
Metabolism of trimethylarsine oxide
Authors: Pickett A Wendy , McBride Barry C , Cullen William R
Published: January 2005

Trimethylarsine oxide [(CH3)3AsO] has been shown to be easily reducible by various biological species, including both aerobic and anaerobic micro‐organisms, some skin organisms, soil bacteria, sludge and rumen fluid. The results suggest an enhanced mobility for arsenic owing to facile production of the volatile (CH3)3As species.
The structure and dynamics of FeH(DMPE)2(BH4), FeH(DEPE)2(BH4) and FeH(DPrPE)2(BH4): Iron complexes containing monodentate borohydride ligands
Authors: Baker Murray V , Field Leslie D
Published: January 2005

FeH(DMPE)2(BH4) [DMPE = 1,2‐bis(dimethylphosphino)ethane] is a stable, diamagnetic complex which can be synthesized readily by borohydride reduction of FeH(DMPE)2Cl or by treatment of Fe(DMPE)2H2 with borane. The complex contains an unsupported BHFe hydrogen bridge. Analogous complexes with bulkier ligands, FeH(DEPE)2(BH4), [DEPE = 1,2‐bis(diethylphosphino)ethane] and FeH(DPrPE)2(BH4) [DPrPE = 1,2‐bis(di‐n‐propylphosphino)ethane], are less stable. In all complexes, in solution the borohydride ligand undergoes rapid internal motion, with all four boron‐bound hydrogens interchanging environments. The barriers for BH4 reorientation (measured by NMR spectroscopy) are in the sequence FeH(DMPE)2(BH)4 > FeH(DEPE)2(BH)4 > FeH(DPrPE)2(BH4).
Synthesis and properties of bis(dialkylphosphino)ethane iron dihydrides
Authors: Baker Murray V , Field Leslie D , Young David J
Published: January 2005

Syntheses and properties of the iron bisphosphinoethane complexes FeH2(PP)2 and FeHCl(PP)2[PPR2PCH2CH2CH2PR2, where RMe (PPDMPE), Et(PPDEPE), and n‐Pr (PPDprPE)] are reported. The complexes can be formed by reduction of the corresponding dichlorides FeCl2(PP)2 with lithium aluminium hydride in THF solution provided that ethanol or more acidic reagents are not employed during the reaction work‐up. The dihydrides are notably basic compounds and can be protonated reversibly by alcohols.

The dihydrides exist as equilibrating mixtures of cis and trans isomers in solution. The cis isomers of each of the dihydrides are fluxional on the NMR timescale and NMR studies indicate that the interconversion of cis isomers does not necessarily proceed via the trans isomer.
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

Environmentally 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

We 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

Norbornene 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

The 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

The 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

Sulfido 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

Schiff 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

Neurotropic 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

[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

A 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

Poly[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

This 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

Dibutyltin‐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

Adducts 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

η3‐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

An 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

In 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

Analysis 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

A 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

Several 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.
Species differences in the metabolism of arsenic compounds
Authors: Vahter Marie
Published: January 2005

Humans are exposed via air, water and food to a number of different arsenic compounds, the physical, chemical, and toxicological properties of which may vary considerably. In people eating much fish and shellfish the intake of organic arsenic compounds, mainly arsenobetaine, may exceed 1000 μg As per day, while the average daily intake of inorganic arsenic is in the order of 10–20 μg in most countries. Arsenobetaine, and most other arsenic compounds in food of marine origin, e.g. arsenocholine, trimethylarsine oxide and methylarsenic acids, are rapidly excreted in the urine and there seem to be only minor differences in metabolism between animal species. Trivalent inorganic arsenic (AsIII) is the main form of arsenic interacting with tissue constituents, due to its strong affinity for sulfhydryl groups. However, a substantial part of the absorbed AsIII is methylated in the body to less reactive metabolities, methylarsonic acid (MMA) and dimethylarsinic acid (DMA), which are rapidly excreted in the urine. All the different steps in the arsenic biotransformation in mammals have not yet been elucidated, but it seems likely that the methylation takes place mainly in the liver by transfer of methyl groups from S‐adenosylmethionine to arsenic in its trivalent oxidation state. A substantial part of absorbed arsenate (AsV) is reduced to AsIII before being methylated in the liver. There are marked species differences in the methylation of inorganic arsenic. In most animal species DMA is the main metabolite. Compared with human subjects, very little MMA is produced. The marmoset monkey is the only species which has been shown unable to methylate inorganic arsenic. In contrast to other species, the rat shows a marked binding of DMA to the hemoglobin, which results in a low rate of urinary excretion of arsenic.
Peripheral vasculopathy in rats induced by humic acids
Authors: Lu Fung‐Jou , Huang Tien‐Shang , Lin Yung‐Sung , Pang Victor Fei , Lin Shih Yuh
Published: January 2005

Adult male Wistar rats averaging 380 g in weight were injected with single doses (100 mg kg−1 body weight) of humic acids intraperitoneally. ‘Black tails’ were noticed 12 days later. In severely affected regions, thrombosis with mild to moderate acute necrotizing vasculitis was seen in most of the blood vessels located in the dermis, subcutaneous fat and muscle. These blood vessels were markedly dilated. Frequently, colonies of a shortrod bacterium of varying sizes were observed in necrotic tissues. There was mild to moderate edema and minimal accumulation of mast cells and macrophages in the dermis. Acute fat necrosis with fibrin deposition was also seen in the subcutaneous fat. Based on the pathological findings, we diagnosed that the tails of Wistar rats which had been injected with humic acids had severe multifocal thrombosis and mild to moderate, multifocal, acute necrotizing vasculitis with bacterial colonization, mild dermatitis, and fat necrosis. The relevance of these observations to the discussions on arsenic as an etiological factor of human Blackfoot disease is examined.
Organometallic complexes with biological molecues, part 3. in vivo cytotoxicity of diorganotin (IV) chloro and triorganotin (IV) chloro derivatives of penicillin g on chromosomes of aphanius fasciatus (pisces, cyprinodontiformes)
Authors: Vitturi R. , Mansueto C. , Gianguzza A. , Maggio F. , Pellerito A. , Pellerito L.
Published: January 2005

In order to obtain a continuous source of mitotic metaphases, gill tissue of Aphaius fasciatus (Pisces, Cyprinodontiformes) has been successfully employed. Results gathered after exposure of fish to R2SnClpenG, R3SnClpenGNa, to the parents R2SnCl2, R3SnCl and to penGNa (penGNa = penicillinGNa; R = methyl, butyl and phenyl) suggest that both the parent organotin (IV) chloride and organotin (IV) chloropenG derivatives are toxic while penGNa exerts no significant toxic activity. Essentially, all of the chromosome abnormalities are classifiable as irregularly staining of chromosomes, breakages, side‐arm bridges or pseudochiasmata.
Use of cartridges for speciation of organotin compounds in environmental samples
Authors: Gomez‐Ariza J. L. , Beltrán R. , Morales E. , Giraldez I. , Ruiz‐Benitez M.
Published: January 2005

The performance of cartridges with different polar and non‐polar stationary phases (C18, C8, C2, phenyl) has been investigated for the quantitative separation of butyltin and phenyltin species (TBT, DBT, MBT, MPT, DPT, TPT), and conditions have been established to optimize the separation, using gas chromatography with a flame photometric detector, to characterize the different organotin species. Optimum separation and preconcentration of organotins is based on retention in a C18 cartridge and elution with 2 cm3 of 1% (v/v) HBr and 0.1% tropolone solution in methanol, being successfully applied to seawater. Finally, the possibilities of the cartridges for selective elution and their use in direct non‐chromatographic speciation are discussed.
Transversely heated graphite atomizer–atomic absorption spectrometry (thga aas) in combination with flow injection analysis system‐hydride generation (fias hg) as a reliable screening method for organolead compounds
Authors: Bettmer J. , Cammann K.
Published: January 2005

The combination of a flow injection analysis system‐hydride generation (FIAS HG) and transversely heated graphite atomizer–atomic absorption spectrometry (THGA AAS) has been applied for the sensitive detection of organolead compounds [e.g. detection limit of trimethyl‐lead species (TriML): 32 ng l−1 for a 0.5 ml sample loop] in the presence of inorganic lead. A mixture of hydrochloric acid and ethylenediaminetetra‐acetic acid (EDTA) as a carrier solution in the flow injection system suppressed interferences of inorganic lead. Calibration with various organolead compounds in the range 0.25–8 μg l−1 was carried out in the presence of 10 mg l−1 Pb2+ without any interferences. Additionally, statistical aspects of the determination of trimethyl‐lead have been studied. Different parameters, e.g. working range, detection limit, recovery function etc., were calculated with respect to quality assurance in metal speciation.