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  • 1990-1994  (9)
  • Analytical Chemistry and Spectroscopy  (5)
  • Lanthanides  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Aspects of the capillary GC analysis of all-trans- and 13-cis-acitretin (1992)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 15 (1992), S. 637-640 
    Details
    ISSN: 0935-6304
    Keywords: Capillary GC ; On-column injection ; Plasma samples ; Retinoid analysis ; Acitretin isomers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The capillary gas chromatographic (CGC) analysis of the der-matological drug trans-acitretin (NeotigasonR) and its cis metabolite is described. Separation of the methyl ester derivatives can be achieved on a 90% biscyanopropylsiloxane phase. The importance of using cold on-column injection and short, thin film capillary columns is discussed. For patients treated with the prodrug of acitretin, etretinate (TigasonR), i.e. the ethyl ester of Neotigason, three compounds have to be separated. Selectivity tuning is required for successful CGC separation. An alternative can be found in the selectivity of ion monitoring mass spectroscopy. Analysis of plasma samples involves liquid-liquid extraction, a derivatization step, and HPLC purification.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240151003
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  • 2
    Electronic Resource
    Electronic Resource
    SFE of PAHs from soils with a high carbon content and analyte collection via combined liquid/solid trapping (1993)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 16 (1993), S. 491-494 
    Details
    ISSN: 0935-6304
    Keywords: Supercritical fluid extraction ; Polynuclear aromatic hydrocarbons ; Liquid/solid traps ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polynuclear aromatic hydrocarbons (PAHs) are recovered from a soil with a high carbon content (ca. 50%) with supercritical fluid extraction (SFE) as well as with conventional Soxhlet extraction. The influence of temperature and modifier volume on SFE efficiency and the effect of a combined liquid/solid trap for analyte collection are investigated in this study. Such traps, which make analyte collection and clean-up possible in one step, are compared with conventional analyte collection in pure organic solvents. A comparison between reproducibility and efficiency of SFE and Soxhlet extraction is presented.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240160810
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  • 3
    Electronic Resource
    Electronic Resource
    Plasma desorption mass spectrometry of phosphopeptides: An investigation to determine the feasibility of quantifying the degree of phosphorylation (1991)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 20 (1991), S. 565-574 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The intact ion yields of phosphotyrosine, phosphothreonine and mono- and diphosphoserine residue-containing peptides have been compared with the non-phosphorylated sequences using plasma desorption mass spectrometry. Equimolar mixtures of the phosphorylated (MP) and non-phosphorylated peptides (M) were also analysed. The positive mass spectra of these mixtures show a higher intensity of the [M + H]+ compared with the [MP + H]+. In the negative mass spectrum, the bias towards the [M - H]- compared with the [MP - H]- was reduced, but the spectra generally did not accurately reflect the stoichiometry.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200200910
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  • 4
    Electronic Resource
    Electronic Resource
    Quantification of molecular secondary ion mass spectrometry by internal standards (1992)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 27 (1992), S. 1148-1150 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210271029
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  • 5
    Electronic Resource
    Electronic Resource
    Synthese und Struktur der ersten Wasserfreien ternären Lithiumnitrate der Lanthanide, Li2[M(NO3)5] (M = La, Pr—Eu) (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 513-516 
    Details
    ISSN: 0044-2313
    Keywords: Synthesis ; Crystal Structure ; Lanthanides ; Ternary Lithium Nitrates ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Structure of the First Anhydrous Ternary Lithium Nitrates of the Lanthanides, Li2[M(NO3)5] (M = La, Pr—Eu).Single crystals of the ternary lithium nitrates of the lanthanides, Li2[M(NO3)5] (M = La, Pr—Eu), are obtained by dissolving the respective anhydrous nitrate, previously obtained by dehydration of M(NO3)3 · 6 H2O at 180°C under vacuum, in a melt of LiNO3. In the crystal structure of Li2[Pr(NO3)5] (orthorhombic, Pnnm, Z = 4, a = 899.6(2), b = 1 052.7(2), c = 1 178.6(2)pm; R = 0.072, Rw = 0.034) there are two crystallographically different Pr3+ ions, each surrounded by six bidentate nitrate ligands. One nitrate group is bridging between Pr1 and Pr2 resulting in a winded chain, ∞1[(O2/2NO2/1)Pr1(NO3)4(O2/2NO2/1)Pr2(O2/2NO2/1)(NO3)4]5-, running along [010]. The chains are packed hexagonally and held together by lithium ions. The coordination polyhydron of Li+ may be described as a bicapped trigonal prism.
    Notes: Einkristalle der ternären Nitrate der Lanthanide vom Typ Li2[M(NO3)5] (M = La, Pr—Eu) erhält man durch Auflösen der zuvor bei 180°C unter Vakuum entwässerten Hydrate M(NO3)3 · 6 H2O in einer Lithiumnitrat-Schmelze. Die Röntgenstrukturanalyse am Beispiel von Li2[Pr(NO3)5] (orthorhombisch, Pnnm, Z = 4; a = 899,6(2); b = 1 052,7(2); c = 1 178,6(2)pm; R = 0,072; Rw = 0,034) zeigt, daß zwei kristallographisch verschiedene Pr3+ vorliegen, die von jeweils sechs zweizähnigen Nitratliganden umgeben sind. Eine Nitratgruppe verbrückt zwischen Pr1 und Pr2, so daß sich eine gewundene Kette gemäß ∞1[(O2/2NO2/1)Pr1(NO3)4(O2/2NO2/1)Pr2(O2/2NO2/1)(NO3)4]5- ergibt, die längs [010] verläuft. Die Kettenstränge sind gemäß einer hexagonalen Stabpackung angeordnet und werden durch Li+-Ionen zusammengehalten. Die Koordination um Li+ kann als zweifach bekapptes trigonales Prisma beschrieben werden.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190313
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  • 6
    Electronic Resource
    Electronic Resource
    Sequential assignments by 1H 2D NMR of oxidized ferredoxins from Clostridium pasteurianum and Clostridium acidurici (1993)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 31 (1993), S. S27 
    Details
    ISSN: 0749-1581
    Keywords: 1H 2D NMR ; Ferredoxins ; Iron-Sulphur Redox protein ; Clostridium ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A 1H 2D NMR investigation of the oxidized 2[4Fe-4S] ferredoxins from Clostridium pasteurianum and C. acidurici was carried out. Sequential assignments through standard HOHAHA and NOESY procedures were obtained for the 2-7, 23-36 and 52-55 sequence segments of both proteins. Additional assignments of the 15-17 and 44-46 segments, linking the clusters, and of a few other residues were made by taking advantage of sequence differences between the two proteins. In summary, only the immediate vicinity of the cysteine ligands could not be identified by the procedure. In these small 2[4Fe-4S] ferredoxins, a large proportion of the resonances is sensitive to the presence of the paramagnetic centres and does not easily display NOE correlations. Nevertheless, long-range NOE peaks that could be observed shed light on the solution structure of these proteins. The close interaction between the N- and C-termini, previously evidenced by x-ray crystallography, was confirmed for both proteins in solution. Small differences between the ferredoxins from C. pasteurianum and C. acidurici were detected in the flexible and variable external 25-30 loop and also in the region separating the clusters. These differences may correlate with small dissimilarities previously observed between some properties of these ferredoxins.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260311308
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  • 7
    Electronic Resource
    Electronic Resource
    [La2Cl3(OAc)2(H2O)7]Cl: Das erste Lanthanid-Acetat-Halogenid-Hydrat mit Chlorid in innerer KoordinationssphäreProfessor Hans-Georg von Schnering zum 60. Geburtstage gewidmet (1991)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 598 (1991), S. 299-306 
    Details
    ISSN: 0044-2313
    Keywords: Lanthanides ; crystal structure ; acetate halides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: [La2Cl3(OAc)2(H2O)7]Cl: The First Lanthanide-Acetate-Halide-Hydrate with Chloride in Inner-Sphere Coordination[La2Cl3(OAc)2(H2O)7]Cl has been obtained as single crystals through the reaction of LaCl3 · 7H2O with diluted acetic acid or from La2O3 with acetyl chloride. In the crystal structure (triclinic, Z = 2, P1 (no. 2), a = 919.6(2), b = 950.7(2), c = 1178.9(2) pm, α = 82.52(1), β = 84.14(1), γ = 64.69(1)°, R = 0.021, Rw = 0.020), La3+ is surrounded by nine ligands (O, Cl). La1 has two chloride and seven oxygen ligands whereas La2 has one chloride and eight oxygen atoms as nearest neighbours. Four of the oxygen ligands of each lanthanum cation originate from a „tetradentate“ acetate anion, the others from crystal water molecules. The „tetradentate“ acetate groups are coordinated not only to one central La3+ as chelate ligands, but also to the „left“ and „right“ La3+ neighbours. Thereby, a one-dimensional infinite cationic chain, 1∞[La2Cl3(OAc)2(H2O)7]+, is formed that runs in the [011] direction. These chains are held together by „lonesome“ chloride ions which are surrounded by (4 + 1) water molecules and connected to the chains via hydrogen bonds.
    Notes: [La2Cl3(OAc)2(H2O)7]Cl wurde in einkristalliner Form durch Umsetzung von LaCl3 · 7H2O mit und in verdünnter Essigsäure oder von La2O3 mit Acetylchlorid erhalten. In der Kristallstruktur (triklin, Z = 2, P1 (Nr. 2); a = 919,6(2); b = 950,7(2); c = 1178,9(2) pm; α = 82,52(1), β = 84,14(1); γ = 64,69(1)°; R = 0,021; Rw = 0,020) ist La3+ von jeweils neun Liganden (O, Cl) umgeben. Dabei weist La1 zwei Chlorid- und sieben Sauerstoff-, La2 dagegen nur einen Chlorid-, jedoch acht Sauerstoff-Liganden als nächste Nachbarn auf. Je vier der Sauerstoff-Liganden in der Koordinationssphäre des Lanthans stammen von einer „vierzähnigen“ Acetatgruppe, die übrigen von Hydratwasser-Molekülen. Die Acetatgruppen koordinieren sowohl am zentralen (chelatisierend) als auch zu den „rechts“ und „links“ benachbarten La3+-Kationen. Hierdurch entstehen eindimensional unendliche, kationische Ketten 1∞[La2Cl3(OAc)2(H2O)7]+, die in Richtung [011] verlaufen. Diese Ketten werden durch „einsame“ Chlorid-Ionen zusammengehalten, die ihrerseits von (4 + 1) Hydratwasser-Molekülen umgeben sind, zu denen Wasserstoffbrücken-Bindungen ausgebildet werden.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19915980127
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  • 8
    Electronic Resource
    Electronic Resource
    Cs[Er6C]I12 und Cs2Lu[Lu6C]Cl18: Beispiele für quaternäre reduzierte Halogenide der Lanthanide mit isolierten „Clustern“ (1992)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 618 (1992), S. 18-25 
    Details
    ISSN: 0044-2313
    Keywords: Lanthanides ; Halides ; Clusters ; Electron Deficiency ; Cesium Lutetium Chloride Carbide ; Cesium Erbium Iodide Carbide ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: CS[Er6C]I12 and cs2Lu[Lu6C]CI18: Examples for Quaternary Reduced Halides of the Lanthanides with Isolated “Clusters”Cs[Er6C]I12 and Cs2Lu[Lu6C]Cl18 were obtained as byproducts through metallothermic reductions of ErI3 and LuCl, with cesium in the presence of carbon in sealed tantalum containers at temperatures ranging from 700 to 940 °C. Cs2Lu[Lu6C]Cl18 (isostructural with Cs2Zr[Zr6H]Cl18, R 3, a = 981.7 pm, c = 2723.2 pm, Z = 3, R = 0.082, R, = 0.053) contains octahedral [Lu6C] clusters which are slightly compressed along the threefold axis and edge-bridged by twelve chloride anions to form [Lu6C]Cl12 units. Six additional Cl in exo positions of the cluster provide octahedral coordination for the seventh Lu3+. Cs+ occupies anticuboctahedral interstices within the Cl+ layers as a part of the (hexagonal) closest packed arrangement. Cs[Er6C]I12 (trigonal, R 3, a = 1112.0pm, c = 2063.8pm, Z = 3, R = 0.094, R, = 0.068) exhibits [Er6C]I12 units as well and shows the structural framework of Sc[Sc6N]Cl12. Instead of Sc3+ in octahedral holes, cesium occupies a regular iodide position within the ccp sheets forming [CsI3] layers. Both halides are compared with other compounds of the lanthanides containing isolated [M6X12] clusters. The extreme electron deficiency is discussed.
    Notes: Cs[Er6C]I12 und Cs2Lu[Lu6C]Cl18 wurden als Nebenprodukte bei der metallothermischen Reduktion von ErI3 bzw. LuCl3 mit Caesium in Gegenwart von Kohlenstoff in verschweißten Tantalkapseln bei 700 bis 940°C erhalten. Cs2Lu[Lu6C]Cl18 (isotyp mit Cs2Zr[Zr6H]Cl18, R3, a = 981,7 pm, c = 2723,2 pm, Z = 3, R = 0,082, Rw = 0,053) ist aus oktaedrischen [Lu6C]-“Clustern” aufgebaut, die entlang der dreizähligen Achse leicht gestaucht sind und mit 12 Chlorid-Ionen über den Oktaederkanten [Lu6C]Cl12-Einheiten bilden. Sechs weitere Cl- besetzen die terminalen Positionen des “Clusters” und bilden eine oktaedrische Umgebung für das siebte Lu3+. Cs+ besetzt antikuboktaedrische Lücken innerhalb der (hexagonal) dichtest gepackten Chlorid-schichten. Cs[Er6C]I12 (trigonal, R 3, a = 1 112,0 pm, c = 2 063,8 pm, Z = 3, R = 0,094, Rw = 0,068) enthält ebenfalls isolierte [Er6C]I12-Einheiten und weist das Verknüpfungsprinzip von Sc[Sc6N]Cl12 auf. Anstelle von Sc3+ in oktaedrischen Lücken besetzt Caesium einen regulären Iodidplatz der kubisch-dichtesten Packung und bildet mit diesen [CsI3]-Schichten aus. Beide Verbindungen werden mit anderen isolierten [M6X12]-“Clustern” der Lanthanide verglichen. Der extreme Elektronenmangel der [M6C]-Einheiten wird diskutiert.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19926180104
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  • 9
    Electronic Resource
    Electronic Resource
    Cs2[Pr6(C2)]I12 - das erste quaternäre reduzierte Halogenid mit isolierten [M6(C2)]-ClusternProfessor Harald Schäfer zum 80. Geburtstage gewidmet (1993)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 1-6 
    Details
    ISSN: 0044-2313
    Keywords: Lanthanides ; Halides ; Clusters ; Cesium Praseodymium Iodide Dicarbide ; Crystal Structure ; Metal-Metal-Bonding ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cs2[Pr6(C2)]I12  -  the First Quaternary Reduced Halide with Isolated [M6(C2)] Clusters.Cs2[Pr6(C2)]I12 is obtained as one of the major products from the reaction of PrI3, cesium and carbon in sealed tantalum containers at 850°C. The crystal structure triclinic, P 1; a=948.1(2), b=953.6(3), c=1 005.2(3) pm; α=71.01(2); β=84,68(3), γ=89.37(2)°; Z=1 contains discrete Pr6I12-type clusters elongated along the pseudo-four-fold axis to accommodate the C2 units (d(C - C)=139 pm). The clusters are connected through common i-aI and a-iI linkages at metal vertices and edges according to Cs2[Pr6(C2)iI6i-aI6/2]a-iI6/2. The cesium cations occupy interstices within the (distorted) iodide layers in a way that “Cs2I18” dimers are formed, in which Cs+ is surrounded by eleven I-. On the basis of the MO scheme of [Sc6(C2]I11, the bonding of the C2 unit is discussed and compared with other cluster compounds containing C2 units.
    Notes: Cs2[Pr6C2)]I12 entsteht als ein Hauptprodukt bei der Reaktion von PrI3 mit Caesium und Kohlenstoff in verschweißten Tantalampullen bei 850°C. Die Kristallstruktur triklin, P 1; a =948,1(2); b = 953,6(3); c = 1 005,2(3) pm; α = 71,01(2); β = 84,68(3); γ=89,37(2)°; Z=1 beinhaltet isolierte monomere Pr6I12-Cluster, jeweils mit einer C2-Hantel als interstitieller Baueinheit. Aufgrund des Platzanspruches der C2-Einheit (d)(C - C)=139 pm entlang der pseudo-vierzähligen Achse sind die [M6(C2)]-Cluster gestreckt. Die Verbrückung untereinander erfolgt über “normale” Halogenbrücken (i-aI und a-iI), so daß als Verknüpfungsmuster Cs2[Pr6(C2)iI6i-aI6/2]a-iI6/2 resultiert. Die Cs+-Ionen besetzen reguläre Iodidplätze innerhalb der (verzerrten) Iodidschichten, wobei zwei Cs+-Ionen eine “Cs2I18”-Einheit bilden, in der jedes Cs+ von elf Iodid-Ionen umgeben ist. Die Bindungen innerhalb des Clusters werden auf der Basis des MO-Diagramms von [Sc6(C2)]I11 diskutiert und mit anderen Verbindungen verglichen, die ebenfalls eine C2-Hantel als interstitielle Einheit besitzen.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19936190103
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