JOURNAL OF FOOD QUALITY, Issue 6 2004
ANGELA DI PINTO
ABSTRACT The authors used a polymerase chain reaction (PCR) assay on buffalo mozzarella, a typical Italian dairy product, from the Apulia markets to evaluate the presence of cow milk and verification of the mozzarella label. The results obtained from 30 mozzarella samples demonstrated the presence of the cow genome in 22/30 samples, highlighting contamination as probable fraudulent adding of cow's milk or use of the same equipments in both working cycles. [source]

A NOVEL MULTIPLEX POLYMERASE CHAIN REACTION FOR SIMULTANEOUS DETECTION OF YERSINIA ENTEROCOLITICA, STAPHYLOCOCCUS AUREUS, AEROMONAS AND SALMONELLA FROM CHICKEN MEAT AND MILK SAMPLES

JOURNAL OF FOOD SAFETY, Issue 2 2010
K. BALAKRISHNA
ABSTRACT Yersinia enterocolitica, Staphylococcus aureus, Aeromonas and Salmonella are among the most important foodborne bacterial pathogens. The majority of human infections caused by all of these organisms are associated with ingestion of undercooked and contaminated meat, dairy products and water where in the secreted bacterial toxins lead to foodborne intoxications. We, here, report a new multiplex polymerase chain reaction (mPCR) assay for the simultaneous detection of these important foodborne bacterial pathogens. The mPCR targeted Ail and virF genes of Y. enterocolitica, nuc and entB genes of S. aureus, aerA and 16S rRNA genes of Aeromonas and invA, an invasion protein A gene of Salmonella. An internal amplification control designed to check the false negative reactions in mPCR was also included. This procedure could detect initial populations of 1,100 cfu/g or /mL within 24 h in experimentally spiked food and water samples. When evaluated on a total of 104 naturally occurring food samples, the mPCR detected two samples to contain S. aureus, one was identified to contain Y. enterocolitica and four samples were identified to contain Salmonella species individually. This was compared with the standard microbiological and biochemical identification procedures. PRACTICAL APPLICATIONS All the microorganisms selected in this study are food and waterborne and contaminate a variety of food items. Pathogenic Y. enterocolitica and Aeromonas species are able to grow and multiply and secrete toxins even at low temperatures. The high throughput and cost-effective multiplex polymerase chain reaction method reported here could be a viable alternative for detection of pathogenic Y. enterocolitica, S. aureus, Aeromonas and Salmonella from food and environmental samples. [source]

RENAL IMPAIRMENT AND HYPERSENSITIVITY REACTION DUE TO EFAVIRENZ

NEPHROLOGY, Issue 6 2008
ELIZABETH CURRY
[source]

STOCK MARKET REACTION TO GOOD AND BAD INFLATION NEWS

THE JOURNAL OF FINANCIAL RESEARCH, Issue 2 2008
Johan Knif
Abstract This article shows that differentiating between good and bad inflation news is important to understanding how inflation affects stock market returns. Summing positive and negative inflation shocks as in previous studies tends to wash out or mute the effects of inflation news on stock returns. More specifically, we find that, depending on the economic state, positive and negative inflation shocks can produce a variety of stock market reactions. We conclude that the effect of inflation on stock returns is conditional on whether investors perceive inflation shocks as good or bad news in different economic states. [source]

SENSITIVITY OF INVESTOR REACTION TO MARKET DIRECTION AND VOLATILITY: DIVIDEND CHANGE ANNOUNCEMENTS

THE JOURNAL OF FINANCIAL RESEARCH, Issue 1 2005
Diane Scott Docking
Abstract We examine whether investor reactions are sensitive to the recent direction or volatility of underlying market movements. We find that dividend change announcements elicit a greater change in stock price when the nature of the news (good or bad) goes against the grain of the recent market direction during volatile times. For example, announcements to lower dividends elicit a significantly greater decrease in stock price when market returns have been up and more volatile. Similarly, announcements to raise dividends tends to elicit a greater increase in stock price when market returns have been normal or down and more volatile, although this latter tendency lacks statistical significance. We suggest an explanation for these results that combines the implications of a dynamic rational expectations equilibrium model with behavioral considerations that link the responsiveness of investors to market direction and volatility. [source]

ANTHOCYANIN INTERACTIONS WITH DNA: INTERCALATION, TOPOISOMERASE I INHIBITION AND OXIDATIVE REACTIONS

JOURNAL OF FOOD BIOCHEMISTRY, Issue 5 2008
MICHAEL R. WEBB
ABSTRACT Anthocyanins and their aglycone anthocyanidins are pigmented flavonoids found in significant amounts in many commonly consumed foods. They exhibit a complex chemistry in aqueous solution, which makes it difficult to study their chemistry under physiologic conditions. Here we used a gel electrophoresis assay employing supercoiled DNA plasmid to examine the ability of these compounds (1) to intercalate DNA; (2) to inhibit human topoisomerase I through both inhibition of plasmid relaxation activity (catalytic inhibition) and stabilization of the cleavable DNA,topoisomerase complex (poisoning); and (3) to inhibit or enhance oxidative single-strand DNA nicking. We found no evidence of DNA intercalation by anthocyan(id)ins in the physiologic pH range for any of the compounds used in this study , cyanidin chloride, cyanidin 3- O -glucoside, cyanidin 3,5- O -diglucoside, malvidin 3- O -glucoside and luteolinidin chloride. The anthocyanins inhibited topoisomerase relaxation activity only at high concentrations (>50 µM), and we could find no evidence of topoisomerase I cleavable complex stabilization by these compounds. However, we observed that all of the anthocyan(id)ins used in this study were capable of inducing significant oxidative DNA strand cleavage (nicking) in the presence of 1 mM dithiothreitol, while the free radical scavenger, dimethyl sulfoxide (DMSO), at concentrations typically used in similar studies, completely inhibited DNA nicking. Finally, we proposed a mechanism to explain the anthocyan(id)in-induced oxidative DNA cleavage observed under our experimental conditions. PRACTICAL APPLICATIONS This study provided improved understanding of the mechanisms by which anthocyan(id)ins interact with DNA. By characterizing the chemistry and solution properties of these important dietary components, we obtained improved information on how the anthocyan(id)ins might function in living systems. [source]

THE SHORT-TERM BEHAVIORAL REACTIONS OF BOTTLENOSE DOLPHINS TO INTERACTIONS WITH BOATS IN DOUBTFUL SOUND, NEW ZEALAND

MARINE MAMMAL SCIENCE, Issue 4 2006
David Lusseau
Abstract Doubtful Sound is home to one of the southernmost resident populations of bottlenose dolphins (Tursiops sp.). This population regularly interacts with scenic cruises. During these interactions, dolphins tend to horizontally and vertically avoid vessels, especially when the behavior of these vessels is intrusive. This study aimed at understanding the behavioral reactions of individuals to these interactions that lead to the disruption of the school's behavioral state. Observing the behavioral events performed by individuals during an interaction can help define the short-term reactions elicited by the boat presence. I recorded the behavioral events performed by all individuals of focal schools. The frequency of occurrence of all events was compared depending on the presence of vessels, their behavior, and the behavioral state of the focal school. Dolphins tended to perform more side flops while interacting with powerboats, a behavior which may be used as a non-vocal communication tool. Moreover, the movement of dolphins became more erratic during interactions with all types of vessels. These effects increased when the boats were more intrusive while interacting. This study shows that the impact of interaction with boats can be minimized if the vessels respect the guidelines in place. [source]

REACTIONS OF CAPTIVE HARBOR PORPOISES (PHOCOENA PHOCOENA) TO PINGER-LIKE SOUNDS

MARINE MAMMAL SCIENCE, Issue 2 2006
Jonas Teilmann
Abstract Pingers on gill nets can reduce bycatch of harbor porpoises. If harbor porpoises habituate to pingers, the effect may be reduced or lost. Two captive harbor porpoises were exposed to three sound types. All sounds were in the frequency band from 100 kHz to 140 kHz, 200 ms long, and presented once per 4 s. The source level was 153 dB re 1 ,Pa RMS at 1 m. Each session consisted of a 10-min presound, a 5-min sound, and a 10-min postsound period. Behavior was recorded on video and on dataloggers placed on the dorsal fin of one animal. The loggers recorded heart rate, swimming speed, dive duration, and depth. The animals responded most strongly to the initial presentations of a sound. Surface time decreased, the heart rate dropped below the normal bradycardia, and echolocation activity decreased. The reactions of both animals diminished rapidly in the following sessions. Should the waning of responsiveness apply to wild animals, porpoises may adapt to the sounds but still avoid nets, or the bycatch may increase after some time. The success of long-term use of pingers may then depend on the variety of sounds and rates of exposure. [source]

MARKET REACTIONS TO THE PASSAGE OF THE FINANCIAL HOLDING COMPANY ACT IN TAIWAN

PACIFIC ECONOMIC REVIEW, Issue 4 2008
Jane-Sue Wang
Abstract. We examine how financial institutions react to various events surrounding the passage of Taiwan's Financial Holding Company Act in June 2001. Empirical results indicate that the financial system experiences significant abnormal returns along the legislative process. Smaller firms have significantly higher abnormal returns, thus lending no support for the hypothesis that larger firms benefit more from the Act. Further analysis shows that the significance of market value is replaced by a significant securities industry effect, thereby consistent with the observation that Taiwan's securities firms are generally smaller in market values and are potential target firms for financial holding companies. [source]

GETTING CREDIT FOR PROACTIVE BEHAVIOR:SUPERVISOR REACTIONS DEPEND ON WHAT YOU VALUE AND HOW YOU FEEL

PERSONNEL PSYCHOLOGY, Issue 1 2009
ADAM M. GRANT
Although proactive behavior is important in organizations, it is not always appreciated by supervisors. To explain when supervisors reward proactivity with higher overall performance evaluations, we draw on attribution theory. We propose that employees' values and affect send signals about their underlying intentions, which influence supervisors' attributions about whether employees deserve credit for proactive behaviors. More specifically, we hypothesize that if employees express strong prosocial values or low negative affect, the proactive behaviors of voice, issue-selling, taking charge, and anticipatory helping will have stronger relationships with supervisors' performance evaluations. We test these hypotheses with samples of 103 managers and their direct supervisors (Study 1) and 55 firefighters and their platoon supervisors (Study 2). The hypotheses were supported in both studies, suggesting that proactive behaviors are more likely to contribute to higher supervisor performance evaluations when employees express strong prosocial values or low negative affect. [source]

UNDERSTANDING REACTIONS TO JOB REDESIGN: A QUASI-EXPERIMENTAL INVESTIGATION OF THE MODERATING EFFECTS OF ORGANIZATIONAL CONTEXT ON PERCEPTIONS OF PERFORMANCE BEHAVIOR

PERSONNEL PSYCHOLOGY, Issue 2 2006
FREDERICK P. MORGESON
Redesigning jobs from a traditional workgroup structure to a semi-autonomous team structure has become increasingly popular, but the impact of such redesigns on employee effectiveness criteria has been mixed. The present longitudinal quasi-experimental study showed that although such a redesign had positive effects on 3 performance behaviors (effort, skill usage, and problem solving), its effectiveness also depended on aspects of the organizational context. In conditions where the organizational reward and feedback and information systems were effective, redesigning work into a semi-autonomous team structure had no discernible effect on performance behaviors. In conditions where these systems were poor, however, such a redesign produced large positive benefits. This suggests that work redesigns that enhance worker autonomy are most effective in contexts where other supportive management systems are absent. [source]

WATCHING THE DETECTIVES: SEASONAL STUDENT EMPLOYEE REACTIONS TO ELECTRONIC MONITORING WITH AND WITHOUT ADVANCE NOTIFICATION

PERSONNEL PSYCHOLOGY, Issue 2 2002
AUDRA D. HOVORKA-MEAD
The present paper tested procedural justice hypotheses about seasonal high school and college student employees' reactions to electronic monitoring with video cameras. Study 1, a field study, explored (a) whether employees receiving advance notification of monitoring offered more favorable justice judgments than employees who did not, and (b) whether employees who saw monitoring procedures and/or consequences as fair returned to the organization the following summer. Results supported the hypotheses: employees viewed monitoring procedures as fairer if they received advance notice. Fairness judgments predicted reemployment Study 2, a scenario-based laboratory experiment, also found that advance notice elicited greater justice beliefs. In addition, Study 2 examined how variations in justification for the monitoring affected justice beliefs. Either strong or weak justifications produced greater procedural justice beliefs than no justification. [source]

Haiderism East of Austria:Reaction, Impact and Parallels

CONSTELLATIONS: AN INTERNATIONAL JOURNAL OF CRITICAL AND DEMOCRATIC THEORY, Issue 3 2000
Miklós Haraszti
First page of article [source]

An Emerging Market's Reaction to Initial Modified Audit Opinions: Evidence from the Shanghai Stock Exchange,

CONTEMPORARY ACCOUNTING RESEARCH, Issue 3 2000
CHARLES J. P. CHEN
Abstract This study investigates the valuation effect of modified audit opinions (MAOs) on the emerging Chinese stock market. Here, the term MAO refers to both qualified opinions and unqualified opinions with explanatory notes. The latter can be considered an alternative form of a qualified opinion in China. The institutional setting in China enables us to find compelling evidence in support of the monitoring role of independent auditing as an institution. First, we find a significantly negative association between MAOs and cumulative abnormal returns after controlling for effects of other concurrent announcements. Further, results from a by-year analysis suggest that investors did not reach negative consensus about MAOs' valuation effect until the second year, exhibiting the learning process of a market without prior exposure to MAOs. Second, we do not observe significant differences between market reaction to non-GAAP- and GAAP-violation-related MAOs. Third, no significant difference is found between market reaction to qualified opinions and market reaction to unqualified opinions with explanatory notes. [source]

Metallic Taste: An Unusual Reaction to Botulinum Toxin A

DERMATOLOGIC SURGERY, Issue 5 2003
Christian Murray MD
BACKGROUND Botulinum neurotoxin formulations are safe and effective agents for the treatment of facial rhytides. OBJECTIVES A patient is described who complained of metallic taste after each treatment with botulinum toxin A (BTX-A). RESULTS The sensation of metallic taste diminished after successive treatments with BTX-A, despite adequate dosing for cosmetic purposes. CONCLUSION Metallic taste is associated with the use of numerous medications; however, the pathogenesis remains unclear. Alteration in zinc metabolism, which may occur with BTX-A administration, has been suggested as a possible mechanism. Although this is the first known report of dysgeusia after BTX-A, physicians and patients may be reassured that the taste alteration was self-limited and was not significantly problematic for the patient in our case. [source]

Self-Limited Adverse Reaction to Human-Derived Collagen Injectable Product

DERMATOLOGIC SURGERY, Issue 10 2000
Brent R. Moody MD
Background. Soft tissue augmentation is a common and safe cosmetic and reconstructive procedure. Objective. We describe a temporary and self-limited adverse reaction to Dermalogen. Methods. Clinical and histologic evaluation following an adverse reaction noted at a Dermalogen skin test site. Results. Our patient was found to have a foreign body reaction to Dermalogen. Conclusion. Dermalogen, a form of acellular human collagen, may induce a foreign body reaction. [source]

Investor Reaction to Inter-corporate Business Contracting: Evidence and Explanation

ECONOMIC NOTES, Issue 3 2006
Fayez A. Elayan
We examine the stock market reaction to 1227 inter-corporate ordinary business contract announcements reported by Dow Jones between January 1, 1990 and December 31, 2001. Around contract announcement dates, we find statistically significant positive average abnormal returns and abnormal trading volume for contractors, but insignificant positive abnormal returns and negative abnormal volume for contractees. Cross-sectionally, contract announcement period returns are higher for contractors who are small relative to the contract size, have higher return volatility, larger market-to-book ratios and higher profitability. The announcement period returns of contract-awarding firms are not significant and are only marginally related to cross-sectional explanatory factors. The results are consistent with two explanatory stories: contractor quasi-rents induced by the winner's curse and information signalling about contractor production costs. The results are not consistent with perfect competition, with contracts having positive net present values for both parties, and with a version of incomplete contracting theory. [source]

Study of Electrochemical Processes with Coupled Homogeneous Chemical Reaction in Differential Pulse Voltammetry at Spherical Electrodes and Microhemispheres

ELECTROANALYSIS, Issue 16 2010
Eduardo Laborda
Abstract Homogeneous chemical reactions coupled to oxidation-reduction processes at electrode surfaces are very common in electrochemistry. In this paper we cope with the application of Differential Pulse Voltammetry at spherical electrodes and microhemispheres for the study of this kind of systems. Analytical expressions are deduced from which the influence of the different experimental variables is examined. Several diagnostic criteria for elucidation of the reaction mechanism from DPV peak parameters are given, as well as working curves for extraction of the kinetic rate constants of the chemical reaction. [source]

Heterogeneous Electron Transfer and Oxygen Reduction Reaction at Nanostructured Iron(II) Phthalocyanine and Its MWCNTs Nanocomposites

ELECTROANALYSIS, Issue 9 2010
Solomon
Abstract Electron transfer and oxygen reduction dynamics at nanostructured iron(II) phthalocyanine/multi-walled carbon nanotubes composite supported on an edge plane pyrolytic graphite electrode (EPPGE-MWCNT-nanoFePc) platform have been reported. All the electrodes showed the category 3 diffusional behaviour according to the Davies,Compton theoretical framework. Both MWCNTs and MWCNT-nanoFePc showed huge current responses compared to the other electrodes, suggesting the redox processes of trapped redox species within the porous layers of MWCNTs. Electron transfer process is much easier at the EPPGE-MWCNT and EPPGE-MWCNT-nanoFePc compared to the other electrodes. The best response for oxygen reduction reaction was at the EPPGE-MWCNT-nanoFePc, yielding a 4-electron process. [source]

Highly Sensitive Electrogenerated Chemiluminescence Detecting Ranitidine Based On Chemically Modifying Microenvironment of the Chemiluminescence Reaction

ELECTROANALYSIS, Issue 11 2005
Xingwang Zheng
Abstract Using a graphite electrode modified with vaseline and NiO, ranitidine showed a strongly ECL enhancing effect for the weak ECL signal of electrooxidation of luminol. Based on this finding, a more sensitive ECL method for ranitidine was firstly proposed. Under the optimum experimental conditions, the ranitidine hydrochloride concentration in the range of 3.0×10,8,9.0×10,6,mol/L was proportional to the enhancing ECL signal and offered a 9×10,9,mol/L detection limit for ranitidine hydrochloride. At the same time, based on the investigation on this ECL reaction mechanism, a new concept, to improve the suitable ECL reaction micro-environment with chemically modified electrode technique for the better analytical performances of ECL analysis was also firstly proposed. [source]

Bioelectrocatalysis of Oxygen Reduction Reaction by Laccase on Gold Electrodes

ELECTROANALYSIS, Issue 13-14 2004
Gautam Gupta
Abstract Direct electron transfer (DET) reaction of oxygen electroreduction catalyzed by enzyme laccase on monolayer modified gold electrodes was studied. Three different monolayers were investigated, from which 4-aminothiophenol was found to be optimal for the direct electron transfer to take place. The electrocatalytic reduction of the oxygen at the electrode surface was found to depend significantly on the method of immobilization. Fungal laccase from Coriolus hirsitus modified with sodium-periodate demonstrated more anodic onset potential for oxygen reduction than the tree laccase from Rhus vernicifera. Physical immobilization of enzyme did not result in any manifestation of bioelectrocatalytic activity. A maximum anodic shift in reduction potential of 300,mV was observed for fungal laccase covalently coupled on the electrode surface. [source]

The Electrochemical Oxidation of 5-Thio-2-nitrobenzoic acid (TNBA) at a Boron Doped Diamond Electrode: Demonstration of a CEC Reaction

ELECTROANALYSIS, Issue 19 2003
Olga Nekrassova
Abstract The oxidation of 5-thio-2-nitrobenzoic acid (TNBA) over a wide pH range has been investigated using cyclic voltammetry at a boron doped diamond electrode. The reaction has been shown to proceed via a CEC reaction process in which at lower pH the thiol moiety of the TNBA species has to undergo deprotonation before oxidation. DIGISIM modelling of the voltammetric profiles deduced a value of 5.2 for the pKa of the thiol moiety which is in good agreement with that obtained from spectrophotometric data. Also reported are the rate constants for all the heterogeneous and homogeneous processes. [source]

Reaction with N,N -Diethyl- p -phenylenediamine: A Procedure for the Sensitive Square-Wave Voltammetric Detection of Chlorine

ELECTROANALYSIS, Issue 8 2003
Hugo Seymour
Abstract The reaction of chlorine and N,N -diethyl- p -phenylenediamine has been studied as a means of generating an analytical voltammetric signal of much improved sensitivity and selectivity for the detection of the former than is possible via direct electrolysis. A reaction mechanism is suggested whereby the chlorine attacks the primary amine of DEPD to form the N -chlorinated product that shows a much enhanced signal under conditions of square-wave voltammetry than does chlorine itself. The analytical parameters were found to vary with concentration of DEPD and a linear range from 17 to 495,,M was achievable with a corresponding limit of detection of 6.8,,M [source]

Caractérisation par PCR de deux souches d'Erwinia carotovora isolées de la rhizosphère de la pomme de terre dans la région du grand Casablanca au Maroc

EPPO BULLETIN, Issue 1 2007
B. Anajjar
Les infections latentes de la pomme de terre causées par les bactéries du genre Erwinia sont responsables de pertes importantes de cette culture, surtout au cours du transport et du stockage au Maroc. Le sol constitue l'un des substrats potentiels dans ces infections. Deux souches bactériennes ont été isolées de la rhizosphère des plantations de pomme de terre dans la province de Mediouna (wilaya du Grand Casablanca). La méthode de PCR (Polymerase Chain Reaction) utilisant les amorces Y1 et Y2 a permis l'identification de ces souches comme étant Erwinia carotovora. Leur pouvoir pathogène a étéévalué sur des tubercules de pomme de terre de la variété Désirée en comparaison avec une souche d'Erwinia carotovora subsp. carotovora isolée de la pomme de terre dans la même rhizosphère. [source]

Dual Luminescent Dinuclear Gold(I) Complexes of Terpyridyl-Functionalized Alkyne Ligands and Their Efficient Sensitization of EuIII and YbIII Luminescence

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2010
Xiu-Ling Li
Abstract Reaction of (tpyC6H4C,CAu)n {tpyC6H4C,CH = 4,-(4-ethynylphenyl)-2,2,:6,,2,-terpyridine} with diphosphane ligands Ph2P(CH2)xPPh2 (x = 2 dppe, 3 dppp, 4 dppb, 5 dpppen, 6 dpph) in CH2Cl2 afforded the corresponding dual luminescent binuclear gold(I) complexes [(tpyC6H4C,CAu)2(,-dppe)] (1), [(tpyC6H4C,CAu)2(, - dppp)] (2), [(tpyC6H4C,CAu)2(,-dppb)] (3), [(tpyC6H4C,CAu)2(,-dpppen)] (4), [(tpyC6H4C,CAu)2(,-dpph)] (5). Crystal structural analysis of complexes 1·2CH2Cl2 and 2·2CH2Cl2 show that the terpyridine moieties are free of coordination in these gold(I)-acetylide-phosphane complexes. Spectrophotometric titration between complex 1 and [Eu(tta)3] (Htta = 2-thenoyltrifluoroacetone) or [Yb(hfac)3(H2O)2] (Hhfac = hexafluoroacetylacetone) gave a 2:1 ratio between Ln(,-diketonate)3 (Ln = Eu, Yb) units and the complex 1 moiety, indicating the formation of Au2Ln2 complexes. Both the luminescence titrations and the luminescence quantum yields of Au2Ln2 (Ln = Eu, Yb) solutions show that the energy transfer occurs efficiently from the binuclear gold(I) antennas 1,5 to EuIII and YbIII centers, and all complexes 1,5 are good energy donors for sensitization of visible and NIR luminescence of EuIII and YbIII ions. [source]

Lithiation of a Cyclen-Derived (NNNN) Macrocycle and Its Reaction with n -Butyllithium

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2010
Sabine Standfuss
Abstract Cyclic polyamine 1,4,7-trimethyl-1,4,7,10-tetraazacyclododecane, (Me3TACD)H (1), was metalated with n -butyllithium in pentane to give [Li2(Me3TACD)2] (2). The structure of this compound is dimeric in the solid state as shown by single-crystal X-ray diffraction. With an excess of nBuLi, nBuLi is incorporated into the product. Depending on the stoichiometry, the compounds [Li3(nBu)(Me3TACD)2] (3) or [Li4(nBu)2(Me3TACD)2] (4) are formed. As shown by single-crystal X-ray diffraction, both molecular structures show a ladder motif. (Me3TACD)H reacted with NaI/Na2CO3 in acetonitrile to give benzene-soluble [NaI(Me3TACD)H] (5). [source]

A Family of 1,1,3,3-Tetraalkylguanidine (H-TAG) Solvated Zinc Aryloxide Precatalysts for the Ring-Opening Polymerization of rac -Lactide

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2010
Julia J. Ng
Abstract Reaction of [Zn(,-TAG){N(SiMe3)2}]2 {TAG = N=C[N(CH2CH3)2N(CH3)2] (DEDMG), N=C{[NCH2CH2CH2CdH2(N,Cd)]N(CH2CH3)2} (DEPYRG) and N=C{[NCH2CH2CH2CH2CeH2(N,Ce)]N(CH2CH3)2} (DEPIPG)} with 2 equiv. of ethanol (EtOH) and 2 equiv. of HOAr {OAr = OC6H3(CMe3)-2-(CH3)-6 (BMP) or OC6H2[C(CH3)3]2 -2,6-(CH3)-4 (4MeDBP)} results in dizinc alkoxides with the general formula [Zn(,-OEt)(OAr)(H-TAG)]2 (1,3). Et2Zn was additionally treated with 2 equiv. of 1,1,3,3-tetramethylguanidine (H-TMG) and H-BMP or HOC6H3(C6H5)2 -2,6 to yield [Zn(BMP)2(H-TMG)2] (4) and [Zn{OC6H3(C6H5)2 -2,6}2(H-TMG)2] (5). Complexes 1, 2, 4, and 5 were characterized by single-crystal X-ray diffraction. Polymerization of rac -lactide with 1,5 and [Zn(,-OMe)(4MeDBP)(H-TMG)]2 (6) were found to generate polylactide (PLA). The bulk powders for all complexes were found to be in agreement with the crystal structures based on elemental analyses, FTIR spectroscopy, and 1H and 13C NMR spectroscopic studies. [source]

Assembly of Dinuclear CuII Rigid Blocks by Bridging Azido or Poly(thiocyanato)chromates: Synthesis, Structures and Magnetic Properties of Coordination Polymers and Polynuclear Complexes

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2010
Sergey V. Kolotilov
Abstract Reaction of a dinuclear cationic copper(II) complex of 4,4,-[2-(3-hydroxyiminobutyl)imino]biphenyl [CuII2(LH)2]2+ with N3, resulted in the formation of a dinuclear azido [CuII2(LH)2(N3)2(H2O)2] complex or a 2D coordination polymer [CuII2(LH)2(N3)2]n. Reaction of the dinuclear complex with [CrIII(NCS)6]3, or [CrIII(NCS)4(NH3)2], produced a 2D polymer {[CuII2(LH)2(CH3CN)2]3[CrIII(NCS)6]2}n or a 1D chain, constructed from tetranuclear units {[CuII2(LH)2][CrIII(NCS)4(NH3)2]2}n. Structures of the compounds were determined by X-ray crystallography and complexes were characterised by the temperature dependency of the magnetic susceptibility and by ESR spectroscopy. Magnetic properties of homometallic compounds were fit with the model of a dimer with the Hamiltonian , = ,J,1·,2. For heterometallic complexes ,MT curves were fit as the superposition of magnetism resulting from both [CuII2(LH)2]2+ and the adjacent CrIII -containing anion. J values for the complexes lie in the range from ,12.74(4) to ,17.77(8) cm,1. It was shown that the 4,4,-biphenyl bridge efficiently mediates exchange interactions. [source]

Reprogramming of a Malonic N-Heterocyclic Carbene: A Simple Backbone Modification with Dramatic Consequences on the Ligand's Donor Properties

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2010
Vincent César
Abstract Reaction of N,N, -dimesitylformamidine with dimethylmalonyl dichloride in dichloromethane in the presence of an excess of triethylamine gives the 2-chloro-4,5-dioxohexahydropyrimidine 1. The corresponding diamidocarbene 3 is generated in situ by further deprotonation with KHMDS at ,40 °C and identified by trapping with S8 to give the fully characterized (including X-ray structure) sulfur adduct 4. It also reacts with [RhCl(cod)]2 to yield the NHC complex [RhCl(3)(cod)] (5) (characterized also by X-ray structure). The donor properties of 3 were evaluated against the established IR [,(CO)] scale from [RhCl(3)(CO)2] (6). The average value of ,(CO) = 2045 cm,1 indicates that the diamidocarbene 3 is much less nucleophilic than structurally relevant six-membered NHCs including the anionic diaminocarbenes previously reported in our group. [source]

Two New Iron(II) Spin-Crossover Complexes with N4O2 Coordination Sphere and Spin Transition around Room Temperature

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 36 2009
Birgit Weber
Abstract The reaction of iron(II) acetate with the tetradentate Schiff base like ligand H2L1 {[3,3,]-[4,5-dihydroxy-1,2-phenylenebis(iminomethylidyne)bis(2,4-pentanedion)]} leads to the formation of the complex [FeL1(MeOH)]. Reaction of this complex with pyridine (py) or N,N,-dimethylaminopyridine (dmap) leads to the two N4O2 -coordinated complexes [FeL1(py)2]·py (1) and [FeL1(dmap)2]·MeOH·0.5dmap (2). Both complexes are spin-crossover compounds that were characterised by using magnetic measurements, X-ray crystallography and temperature-dependent 1H NMR spectroscopy. Special attention was given to the role of the two hydroxy groups on the phenyl ring in the formation of a hydrogen-bonding network and the influence of this network on the spin-transition properties. Although only a gradual spin crossover was observed for both complexes, the transition temperature was shifted to higher temperatures relative to that of the complexes with no additional hydroxy groups at the Schiff base like ligand. The hydrogen-bonding network was responsible for this effect.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]