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1.
Gerard de Leeuw John S. Field Raymond J. Haines Beth McCulloch Elsie Meintjies Christiaan Monberg Gillian M. Olivier Praveen Ramdial Clifford N. Sampson Beate Sigwarth Nick D. Steen Kandasamy G. Moodley 《Journal of organometallic chemistry》1984,275(1):99-111
Reaction of [Fe2(CO)9] with a half molar amount of R2PYPR2 (Y = CH2, R = Ph, Me, OMe or OPri; Y = N(Et), R = OPh, OMe or OCH2; Y = N(Me), R = OPri or OEt) leads to the ready formation of a product which on irradiation with ultraviolet light rapidly decarbonylates to the heptacarbonyl derivative [Fe2(μ-CO)(CO)6{μ-R2PYPR2}]. Treatment of the latter with a slight excess of the appropriate ligand results, under photochemical conditions, in the formation of the dinuclear pentacarbonyl complex [Fe2(μ-CO)(C))4{μ-R2PYPR2}2] but under thermal conditions in the formation of the mononuclear species [Fe(CO)3{R2PYPR2}]. Reaction of [Ru3(CO)12] with an equimolar amount of (RO)2PN(R′)P(OR)2 (R′ = Me, R = Pri or Et; R′ = Et, R = Ph or Me) under either thermal or photochemical conditions produces [Ru3(CO)10{μ-(RO)2PN(OR)2}] which reacts further with excess (RO)2PN(R′)P(OR)2 on irradiation with ultraviolet light to afford the dinuclear compound [Ru2(μ-CO)(CO4{μ-(RO)2PN(R′)P(OR)2}2]. The molecular structure of [Ru2(μ-CO)(CO)4{μ-(MeO)2PN(Et)P(OMe)2}2], which has been determined by X-ray crystallography, is described. 相似文献
2.
da Silva JK Andrade EH Kato MJ Carreira LM Guimarães EF Maia JG 《Natural product communications》2011,6(9):1361-1366
The leaves and twigs of Piper krukoffii, collected in the Carajás National Forest, north Brazil, yielded essential oils (2.0% and 0.8%), the main constituents of which were myristicin (40.3% and 26.7%), apiole (25.4% and 34.1%) and elemicin (2.8% and 3.0%). The antioxidant activities of the oils, methanol extract and its sub-fractions were evaluated. The DPPH EC50 values varied from the ethyl acetate sub-fraction (73.4 +/- 3.7 microg/mL) to the methanol extract (24.9 +/- 0.8 microg/mL), and the ABTS TEAC values ranged in the same order from 265.7 to 349.2 microMol TE/g. These results indicated a significant antioxidant activity for the plant. The lignans (-)-kusunokin, yatein, (-)-hinokin and cubebin were identified in the methanol extract. The hydro-methanolic sub-fraction showed a high value for total phenol content (106.5 +/- 0.7 mg GAE/g), as well as 1H NMR signals for sugar moieties. Crude extracts and sub-fractions were also able to inhibit beta-carotene bleaching, varying from 22.4 to 47.1%. The oils from the leaves and twigs showed strong larvicidal (21.4 and 3.6 microg/mL) and fungicide (0.5 and 0.1 microg/mL) activities. 相似文献
3.
A Echalier E Cot A Camasses E Hodimont F Hoh P Jay F Sheinerman L Krasinska D Fisher 《Chemistry & biology》2012,19(8):1028-1040
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4.
Traces and small amounts of bismuth can be separated from gram amounts of thallium and silver by successively eluting these elements with 0.3M and 0.6M nitric acid from a column containing 13 ml (3 g) of AG50W-X4, a cation-exchanger (100-200 mesh particle size) with low cross-linking. Bismuth is retained and can be eluted with 0.2M hydrobromic acid containing 20% v/v acetone, leaving many other trace elements absorbed. Elution of thallium is quite sharp, but silver shows a small amount of tailing (less than 1 gmg/ml silver in the eluate) when gram amounts are present, between 20 and 80 mug of silver appearing in the bismuth fraction. Relevant elution curves and results for the analysis of synthetic mixtures containing between 50 mug and 10 mg of bismuth and up to more than 1 g of thallium and silver are presented, as well as results for bismuth in a sample of thallium metal and in Merck thallium(I) carbonate. As little as 0.01 ppm of bismuth can be determined when the separation is combined with electrothermal atomic-absorption spectrometry. 相似文献
5.
Synthesis of Linear (Z)‐α,β‐Unsaturated Esters by Catalytic Cross‐Metathesis. The Influence of Acetonitrile
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Elsie C. Yu Brett M. Johnson Erik M. Townsend Prof. Richard R. Schrock Prof. Amir H. Hoveyda 《Angewandte Chemie (International ed. in English)》2016,55(42):13210-13214
Kinetically controlled catalytic cross‐metathesis reactions that generate (Z)‐α,β‐unsaturated esters selectively are disclosed. A key finding is that the presence of acetonitrile obviates the need for using excess amounts of a more valuable terminal alkene substrates. On the basis of X‐ray structure and spectroscopic investigations a rationale for the positive impact of acetonitrile is provided. Transformations leading to various E,Z‐dienoates are highly Z‐selective as well. Utility is highlighted by application to stereoselective synthesis of the C1–C12 fragment of biologically active natural product (?)‐laulimalide. 相似文献
6.
Terence V. Ashworth Anthony A. Chalmers David C. Liles Elsie Meintjies Hester E. Oosthuizen Eric Singleton 《Journal of organometallic chemistry》1984,273(2):C49-c52
[Ru(2–6-η-bicyclo[5.1.0]octadienyl)(PMe2Ph)3][PF6], formed from the reaction of cyclooctatetraene with [RuH(COD)(PMe2Ph)3][PF6] (COD = cycloocta-1,5-diene), has been characterised spectroscopically from 1J(CH) coupling constants and an X-ray structural analysis; the bicyclic ligand contains an elongated bridging CC bond (1.63 Å). 相似文献
7.
A spectrophotometric method for determining iron in the range 0·001–0·125% in high-purity niobium, tantalum, molybdenum and tungsten metals is described. After sample dissolution and reduction of iron to the bivalent state with ascorbic acid and hydroxylamine hydrochloride, the red complex formed between ironII and bathophenanthroline (4,7-diphenyl-1,10-phenanthroline) is extracted into n-arnyl alcohol and the absorbance of the resulting extract is determined at 536 mμ. Interference from copper is eliminated with thiourea. Cobalt, cadmium, nickel, manganese and zinc also interfere but the amounts of each of these impurities present in the four high-purity metals described are so low that their interference effects are negligible in the proposed method. Highly reproducible and precise results can be obtained with careful control of the pH during reduction and extraction. 相似文献
8.
P. Demont E. de Haën A. H. Low A. Scheibe C. Carrez R. Kaack A. Eichstädt R. Intonti Jod Alkali G. M. Kline S. F. Acrce L. Eynon J. H Lane F. A. Dykins D. T. Englis J. M. Kolthoff J. Fiehe W. Kordatzki Fr. Lucius H. Bredereck W. W. Oppel E. Pinoff V. E. Levine H. Molisch C. Neubergs Anna May Hubbell W. E. Malinowski K. Bernhauer C. I. Kruisheer J. Tillmans Elsie May Widdowson H. C. Hagedorn B. N. Jansen Ch. S. Hanes E. Schmidt M. Atterer H. Schnegg J. Großfeld M. Schnetka H. Fineke C. I. Krnischeer J. J. J. Dingemans S. Byall J. A. Ambler A. P. Briggs 《Analytical and bioanalytical chemistry》1932,90(9-10):382-397
9.
Supramolecular Assemblies of Nucleoside Functionalized Carbon Nanotubes: Synthesis,Film Preparation,and Properties
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Dr. Alessandra Micoli Dr. Antonio Turco Elsie Araujo‐Palomo Prof. Armando Encinas Prof. Mildred Quintana Prof. Maurizio Prato 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(18):5397-5402
Nucleoside‐functionalized multi‐walled carbon nanotubes ( N‐MWCNTs ) were synthesized and characterized. A self‐organization process using hydrogen bonding interactions was then used for the fabrication of self‐assembled N‐MWCNTs films free of stabilizing agents, polymers, or surfactants. Membranes were produced by using a simple water‐dispersion‐based vacuum‐filtration method. Hydrogen‐bond recognition was confirmed by analysis with IR spectroscopy and TEM images. Restoration of the electronic conduction properties in the N‐MWCNTs membranes was performed by removing the organic portion by thermal treatment under an argon atmosphere to give d‐N‐MWCNTs . Electrical conductivity and thermal gravimetric analysis (TGA) measurements confirmed the efficiency of the annealing process. Finally, oxidative biodegradation of the films N‐MWCNTs and d‐N‐MWCNTs was performed by using horseradish peroxidase (HRP) and low concentrations of H2O2. Our results confirm that functional groups play an important role in the biodegradation of CNT by HRP: N‐MWCNTs films were completely biodegraded, whereas for d‐N‐MWCNTs films no degradation was observed, showing that the pristine CNT undergoes minimal enzyme‐catalyzed oxidation This novel methodology offers a straightforward supramolecular strategy for the construction of conductive and biodegradable carbon nanotube films. 相似文献
10.
Marques AM Barreto AL Batista EM Curvelo JA Velozo LS Moreira Dde L Guimarães EF Soares RM Kaplan MA 《Natural product communications》2010,5(11):1837-1840
Analyses of essential oils obtained from fresh and dried leaves and inflorescences of Piper clausenianum were performed using GC-FID, GC-MS and NMR techniques. Forty compounds were detected for these four oils with the total of identified constituents ranging from 88.7% for the dried inflorescences to 97.7% for the dried leaves. Sesquiterpenes were the main constituents in the volatile fraction from leaves with a high percentage of (E)-nerolidol (up to 83%). However, monoterpenes were identified in greater amount in the inflorescences, with linalool percentages from 50% up. The essential oils from fresh leaves and inflorescences were submitted to anti-parasitic activity against a strain of Leishmania amazonensis. Both samples showed biological activity, but the essential oil from P. claussenianum fresh leaves, which was rich in (E)-nerolidol, showed effective growth inhibition of L. amazonensis due to the high percentage of this metabolite in the mixture. 相似文献