Cảm ơn chị Châu Nguyệt Trang Thanh đã đóng góp cho Thự Viện ChemVN. Các bạn quan tâm hãy vào http://lib.chemvn.net để download nhé.
Anh cũng xin được góp hai bài cho thư viện.
Bài 1:
Highly enantioselective and cis-diastereoselective cyclopropanation of olefins catalyzed by ruthenium complexes of (iminophosphoranyl)ferrocenes
Tetrahedron Letters 48 (2007) 8014–8017
Vo D. M. Hoang, Pattubala A. N. Reddy and Tae-Jeong Kim
Abstract—Chiral (iminophosphoranyl)ferrocenes (1 and 2) are highly efficient ligands to achieve high diastereoselectivity (up to 95/5 dr in favor of the cis-isomer) as well as enantioselectivity (up to 99% ee) in Ru-catalyzed asymmetric cyclopropanation of various olefins. Reversal in diastereoselectivity is found as a function of metal-to-ligand ratio in the reaction of styrene.
Bai 2:
Asymmetric Allylic Oxidation Catalyzed by Copper(I) Complexes of Chiral (Iminophosphoranyl)ferrocenes
Organometallics 2008, 27, 1026–1027
Vo D. M. Hoang, Pattubala A. N. Reddy, and Tae-Jeong Kim
Summary: The chiral (iminophosphoranyl)ferrocenes 1-3 are highly Versatile ligands in Cu-catalyzed asymmetric allylic oxidation of a series of cyclic olefins with tert-butyl perbenzoate, achieVing almost complete enantioselectiVity (up to 99% ee) in a reasonably short period of time (36 h).
Bluemonster: Em đã cho hai bài báo này vào thư viện, em delete link download anh cung cấp nhé. Cảm ơn anh.
Cảm ơn anh Võ Đỗ Minh Hoàng - Shampa đã đóng góp các bài báo vào thư viện ChemVN. Các bạn quan tâm hãy vào http://lib.chemvn.net để download nhé.
Bai 2: Asymmetric Allylic Oxidation Catalyzed by Copper(I) Complexes of Chiral (Iminophosphoranyl)ferrocenes
Organometallics 2008, 27, 1026–1027
Vo D. M. Hoang, Pattubala A. N. Reddy, and Tae-Jeong Kim
Summary: The chiral (iminophosphoranyl)ferrocenes 1-3 are highly Versatile ligands in Cu-catalyzed asymmetric allylic oxidation of a series of cyclic olefins with tert-butyl perbenzoate, achieVing almost complete enantioselectiVity (up to 99% ee) in a reasonably short period of time (36 h).
Cảm ơn thầy Nguyễn Văn Đông – giotnuoctrongbienca đã đóng góp bài báo cho thư viện ChemVN. Các bạn quan tâm hãy vào http://lib.chemvn.net để download nhé.
- A simple method for synthesis of organotin species to investigate extraction procedures in sediments by isotope dilution-gas chromatography-inductively coupled plasma mass spectrometry
Sunil J. Kumar, Solomon Tesfalidet, James P. Snell, Dong Nguyen Van and Wolfgang Frech
Abstract: A rapid method for the synthesis of phenyltin species based on the phenylation of tin iodide was developed and a standard of 124Sn, enriched monophenyltin (MPhT), diphenyltin (DPhT) and triphenyltin (TPhT) was produced. Isotope enriched species were added to and equilibrated with the certified reference material BCR 646 to evaluate different extraction procedures currently in use for the determination of organic tin species in sediments. Samples were measured by gas chromatography-inductively coupled plasma mass spectrometry (GC-ICP-MS) with species specific isotope dilution (SSID) calibration. For TPhT measurement results agreed with the certified values for extraction methods using tropolone in diethyl ether alone or in the presence of NaCl and HCl as well as with 50% HBr. However, with 50% HBr, concentrations obtained for DPhT and MPhT were above the upper limit (2 ) of the certification. The stability of phenyltin species was studied by comparing their signal magnitudes in spike solutions generated directly after derivatisation with those obtained after applying the extraction–derivatisation procedures. Degradation of phenyltin species was matrix dependent and appeared for most of the extraction methods investigated. For water standards and BCR 646, extraction with methanol combined with dichloromethane or methanol combined with acetic acid gave no degradation when applied with less than 20 min ultrasonication. Extraction efficiencies for these two methods were however low for the BCR 646 matrix, in particular for DPhT and MPhT.
- Preparation, preservation and application of pure isotope-enriched phenyltin species Dong Nguyen Van1, Siva Rama Krishna Muppala1, Wolfgang Frech1 and Solomon Tesfalidet1
Abstract: A method combining liquid/liquid extraction and chromatographic fractionation has been developed for the preparation of pure monophenyltin (MPhT), diphenyltin (DPhT), and triphenyltin (TPhT), synthesized from isotope-enriched Sn metal using phenylation of SnI4 in diethylether (DEE) followed by quenching with HBr and water. After two successive extractions of the aqueous HBr phase with DEE, >99% of both DPhT and TPhT was recovered in the combined DEE phase and 94% of the MPhT remained in the aqueous phase. The MPhT in the aqueous phase was extracted into dichloromethane. The organic phases were vaporized and the PhTs were redissolved in MeOH/water/acetic acid/sodium acetate (59/30/6/8, v/v/v/w), which was also used as storing solution. Aliquots of the two solutions containing either DPhT and TPhT or MPhT were injected into a silica-based C18 column for isolating and purifying single species. The yields of pure MPhT, DPhT, and TPhT, each synthesized from isotope-enriched 118Sn metal, 122Sn metal, and 124Sn metal, were better than 99%. After chromatographic separation, the single phenyltin compounds were mixed to prepare a spike for multiple-isotope species-specific isotope dilution (MI-SSID). MI-SSID was successfully used to determine phenyltin compounds in the certified reference material, mussel tissue BCR CRM-477. At −20 °C, all of the fractionated phenyltin species were stable in the storage solution for at least 197 days. When these standards were stored at 4 °C or 22 °C, 4–6% of the DPhT and TPhT degraded within 27 days. The degradation of DPhT and TPhT increased with the ionic strength and acidity of the storage solution.
Keywords: Chromatographic fractionation - Phenyltin speciation - Multi-isotope species-specific isotope dilution - Production of phenyltin species - Inductively coupled plasma mass spectrometry
- Speciation analysis of butyl- and phenyltin compounds in environmental samples by GC separation and atomic spectrometric detection
Abstract: The main goal of the work presented in this thesis is to improve the reliability of existing methods for speciation analysis of organotin compounds
Species-specific isotope dilution (SSID) calibration in combination with gas chromatography – inductively coupled plasma mass spectrometry was used to investigate the transformation of phenyltin species during sample preparation. Isotope-enriched phenyltin species were synthesized from corresponding isotope-enriched tin metals. SSID with a mixture of phenyltin species (PhTs) from one isotope was used to evaluate different extraction procedures for the determination of PhTs in fresh water sediment. Preparative liquid chromatography was used to produce single isotope-enriched phenyltin species making a multi-isotope spike (MI) SSID calibration possible. Different extraction procedures for the analysis of phenyltin species in biological samples were evaluated by applying MI-SSID. Degradation of TPhT and DPhT during sample extraction was observed and quantified. Accurate results were therefore obtained. A sample preparation procedure using mild extraction conditions with reasonable recoveries is described.
The stability of organotin standards was investigated under different storage conditions. Mono- and diphenyltin were found to be redistributed and degraded during storage in methanol but were stabilized in sodium acetate/ acetic acid. A fast redistribution between monobutyl- and diphenyl tin has been observed and therefore it is therefore recommended that standards be derivatized as soon as possible after butyl- and phenyltin standards are mixed.
Included in the thesis is also an investigation of the analytical potential of using instrumentation based on atomic absorption spectrometry (AAS) for speciation analysis of organotin compounds. The method was based on gas chromatographic separation, atomization in a quartz tube and detection by line source (LS) AAS and for comparison, by state of the art continuum source (CS) AAS. Analytical performances of CSAAS system were found to be better compared to LSAAS.
- Redistribution reactions of butyl- and phenyltin species during storage in methanol
Dong Nguyen Van, Richard Lindberg and Wolfgang Frech
Abstract: The stability of organotin species, which are frequently used as standards, in methanol has been investigated by gas chromatography coupled to either quartz furnace atomic absorption spectrometry, inductively coupled plasma mass spectrometry or mass spectrometry. Ethylation with sodium tetraethylborate was used during sample preparation. The species composition of single or mixed standard solutions at a concentration of 10 µg g–1 was investigated after storing at –20 °C, +4 °C and +22 °C for various time periods. All butyltin species (monobutyltin—MBT, dibutyltin—DBT and tributyltin—TBT) were found to be stable for all storage conditions, even when mixed. The single triphenyltin (TPhT) standard was also stable, whereas mono-and diphenyltin (MPhT; DPhT) were unstable. MPhT redistributed to DPhT and inorganic tin (IOT), while DPhT redistributed to MPhT and to a minor extent to TPhT. In a mixture containing MBT, DBT, TBT, MPhT, DPhT and TPhT, besides the above mentioned reactions, DPhT was found to react strongly with MBT forming up to 73% monobutyl-monophenyltin (MBMPhT) and MPhT. The composition of MBMPhT was investigated by GC-MS. Suggestions for the type of reactions leading to the redistribution of OT species are outlined and suggestions on how to prepare stable OT standards are made.
- A comparison between continuum- and line source AAS for speciation analysis of butyl- and phenyltin compounds
Dong Nguyen Van, Bernard Radziuk and Wolfgang Frech
Abstract: The analytical potential of using instrumentation based on AAS for speciation analysis was investigated. Organic tin (OT) species were determined following gas chromatographic (GC) separation, atomization in a quartz tube (QT) and detection by line source AAS (LSAAS) and, for comparison, by state of the art continuum source AAS (CSAAS). For an unbiased comparison of the AAS instruments, their working conditions were individually optimized. For CSAAS, the linear range was limited by the GC column capacity (10–1600 ng g–1) and for LSAAS this range was limited by stray radiation (20–1000 ng g–1). With background correction, the instrumental LODs for OT were 6–22 pg as tin for CSAAS, while for LSAAS corresponding values were five to ten times poorer. Without background correction, the LOD of CSAAS was twice as good as that of LSAAS. For method validation, two certified reference materials, Harbour Sediment BCR-646 and Oyster Tissue BCR-710, were analysed.
Cảm ơn thầy Nguyễn Quốc Chính đã đóng góp PhD thesis vào thư viện ChemVN. Các bạn quan tâm hãy vào lib.chemvn.net để download nhé.
PhD Thesis: New Routes to Inorganic Materials: Single-Source Precursors for Semiconductors
Department of Chemistry, The University of Manchester 2008
Abstract:
The work herein describes the synthesis and characterization of single source precursors (SSPs) and the results of deposition experiment using these precursors to grow metal selenide thin films by chemical vapor deposition (CVD).
The first part of the thesis reports the facile and reproducible methods for the syntheses of diseleno and thioselenophosphinate ligands and complexes. Several novel ligands including (iPr2PSe)2Se, (iPr2PSe)2Se2, (Ph2PSe)2Se, (HNEt3)(iPr2PSe2), (HNEt3)(Ph2PSe2), (HNEt3)(tBu2PSe2), (HNEt3)(iPr2PSSe) and their metal complexes have been synthesized with high yield and purity. All compounds have been characterized by nuclear magnetic resonance (NMR), mass spectroscopy (MS) and elemental analysis. Most compounds have been structurally characterized by single crystal X-ray crystallography.
In part two of the thesis, these newly developed single source precursors have been used for deposition thin films of CdSe, PbSe, Cu2-xSe, In2Se3, and CuInSe2 by aerosol-assisted chemical vapor deposition (AACVD). The thin films have been analyzed by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive analysis of Xrays (EDAX)
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