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  • 1
    Electronic Resource
    Electronic Resource
    An automated, open-access service to synthetic chemists: Thermospray mass spectrometry (1994)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 8 (1994), S. 632-636 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Nuclear magnetic resonance (NMR) and mass spectrometry (MS) are the major spectroscopic tools used by synthetic organic chemists to monitor the steps of their syntheses. Rapid confirmation of the structure at each synthetic step is vital for efficient progress to the desired product. In many laboratories automated open-access NMR is routine. This often leaves mass spectrometry as a rate-limiting step in structure confirmation. The key information the chemist needs from a mass spectrum is the relative molecular mass (RMM). We have therefore developed an automated, open-access thermospray mass spectrometry service, in which a chemist logs a sample into a queue on the mass spectrometer, and a short time later takes the mass spectrum away. The whole process occurs without any intervention by a mass spectrometrist. This has made mass spectra available as rapidly as NMR spectra, so that chemists can obtain the data they need to confirm synthetic structures within less than two hours.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290080812
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  • 2
    Electronic Resource
    Electronic Resource
    Sterisch gehinderte Olefine, V. Synthese und Röntgenstrukturanalyse von trans-1-Ethyl-2-(1-ethyl-2-adamantyliden)adamantan, einem hochgespannten Ethylen. Vergleich mit Kraftfeld-Rechnungen (1980)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 113 (1980), S. 739-749 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Sterically Hindered Olefins, V. Synthesis and X-Ray Structure Analysis of trans-1-Ethyl-2-(1-ethyl-2-adamantylidene)-adamantane, a Highly Hindered Ethylene. Comparison with Force-Field CalculationsSynthesis of trans-1-ethyl-2-(1-ethyl-2-adamantylidene)adamantane (2) starting from 1-ethyl-2-adamantanone (1) is described. The structure of 2 was determined by X-ray structure analysis (2(C2) symmetry). Steric hindrance results in a torsion and an out-of-plane deformation of the CC double bond, and also is evident by characteristic elongations of bond lengths and by bond angle deformations. The CC double bond, e.g., is elongated to 1.358 Å, the vinylic bonds with a quaternary carbon atom are elongated to 1.563 Å. The strongest bond angle deformation occurs at the substituted sp3-hybridized C-atoms in the allylic positions increasing one angle to 122.1°. The geometry of 2 is compared with the parent compound adamantylideneadamantane (3). Calculations using Allinger's force-field show for 2 and 3 a sufficient agreement with the experimentally determined structure parameters and an increased strain energy by 28.1 kcal mol--1. The force-field calculations have been extended to the analogous adamantylideneadamantanes 4 - 7.
    Notes: Es wird die Synthese von trans-1-Ethyl-2-(1-ethyl-2-adamantyliden)adamantan (2) aus 1-Ethyl-2-adamantanon (1) beschrieben. Die Struktur von 2 wurde durch Röntgenstrukturanalyse bestimmt (2(C2)-Symmetrie). Die starke sterische Spannung in 2 äußert sich in einer Torsion um die C = C-Doppelbindung bei einer gleichzeitigen pyramidalen Verzerrung der Konfiguration ihrer C-Atome, sowie in charakteristischen Bindungsaufweitungen und Winkeldeformationen. Die C = C-Doppelbindung verlängert z.B. auf 1.358 Å; die vinylständigen C — C-Einfachbindungen mit einem quartären Kohlenstoff verlängern auf 1.563 Å. Die stärkste Winkeldeformation erfolgt an den substituierten, allylständigen sp3-hybridisierten C-Atomen (Vergrößerung eines Winkels auf 122.1°). Die Geometrie von 2 wird mit dem weniger gespannten, unsubstituierten Adamantylidenadamantan (3) verglichen. Kraftfeld-Rechnungen nach Allinger für 2 und 3 ergeben eine hinreichend gute Übereinstimmung mit den experimentell ermittelten Strukturparametern und eine um 28.1 kcal/mol höhere Spannungsenergie für 2. Die Kraftfeld-Rechnungen wurden auf analoge Adamantylidenadamantan-Derivate (4 - 7) ausgedehnt.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19801130231
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  • 3
    Electronic Resource
    Electronic Resource
    Chemical reactions on the surface of metal nanoparticles studied by optical spectroscopy (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 353-360 
    Details
    ISSN: 0268-2605
    Keywords: surface chemistry ; sodium nanoclusters ; optical spectroscopy ; plasmon excitation ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The influence of molecular adsorbate layers on surface plasmon excitation in small supported metal particles has been investigated and exploited to study adsorption reactions on their surfaces. For this purpose sodium nanoclusters on quartz and LiF substrates served as model systems. Their optical transmission spectra are dominated by two maxima which are due to the excitation of surface plasmon resonances in the direction of the long and short axes of the oblate particles. By recording the spectra under ultrahigh-vacuum conditions and, subsequently, after exposure to gases such as O2, N2O, CO2, H2 and N2, changes in the optical spectra can be identified if the clusters are covered by as little as half a molecular monolayer. Depending on the adsorbed molecules, different modifications of the maximum position, the width and the amplitude of the surface plasmon resonances are observed. The results of a series of measurements together with calculations using the quasi-static approximation indicate that the variations in the spectra allow one to distinguish between physisorption and chemisorption, i.e. to characterize the strength of the chemical bond. In addition, diffusion of the molecules into the bulk of the particles can be detected. Particularly interesting is the observation that the clusters can experience a change in their shape if gases such as O2 or CO2 react with their surface. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Glutathione S-transferases: Two-dimensional electrophoretic protein markers of lead exposure (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 1332-1335 
    Details
    ISSN: 0173-0835
    Keywords: Two-dimensional nonequilibrium pH gradient gel electrophoresis ; Rat kidney ; Polyacrylamide gel electrophoresis ; Lead exposure ; Glutathione S-transferase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Glutathione S-transferases (GST) are a family of detoxification isoenzymes that catalyze the conjugation of xenobiotics and their metabolites with reduced glutathione. Lead exposure in rats is known to induce GST isoenzymes in the liver and kidney. These changes in expression have potential use as biomarkers of lead exposure. Because two-dimensional electrophoresis (2-DE) enables one to analyze both protein abundance changes and chemical changes in protein structure, 2-DE was used to determine the effect of in vivo lead exposure on GST isoform expression in rat kidney cytosols. Male Sprague-Dawley rats were exposed to inorganic lead, and proteins were separated by conventional ISO-DALT and NEPHGE-DALT techniques and blotted for immunological identification. Lead exposure caused detectable inductions in both GSTP1 and GSTM1 and quantifiable charge modification in GSTP1. These preliminary data confirm the utility of 2-D electrophoretic GST analysis as indicative of lead exposure and toxicity and support its use for further elaboration of lead's effects on renal protein expression.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150190821
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis and Properties of Methylthiopyrazolo[3,4-d]pyrimidine 2′-Deoxy-β-D-ribonucleosides (1992)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1992 (1992), S. 1165-1170 
    Details
    ISSN: 0170-2041
    Keywords: Pyrazolo[3,4-d]pyrimidine ; Pyrazoles ; 2′-Deoxyribonucleosides ; Glycosylation ; Cytotoxicity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the 3- and 4-(methylthio)pyrazolo[3,4-d]pyrimidine N1- and N2-2′-deoxy-β-D-ribonucleosides 2b, 15 is described. Anionic glycosylation of 5-amino-3-(methylthio)-4-pyrazolecarbonitrile (4) or 4-(methylthio)pyrazolo[3,4-d]pyrimidine (12) with 2-deoxy-3,5-di-O-(4-methylbenzoyl)-α-D-erythro-pentofuranosyl chloride (5) gave the regioisomeric N1-and N2-nucleosides 6, 7, 13, and 14. The N1 isomer was the main product in the reaction of 12, and the N2 compound was the preferred product in the glycosylation of 4. Glycosylation in suspension (12) yielded an appreciable amount of the N2 α-D-isomer 16. 4-Aminopyrazolo[3,4-d]pyrimidine 2′-deoxyribonucleosides 3a, b with a methylthio group at C-3 are resistant to deamination by adenosine deaminase and inhibit the proliferation of leukemia cell lines.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1992199201191
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  • 6
    Electronic Resource
    Electronic Resource
    Differential expression of cytosolic proteins in the rat kidney cortex and medulla: Preliminary proteomics (1998)
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2491-2497 
    Details
    ISSN: 0173-0835
    Keywords: Cortex ; Cytoplasm ; Two-dimensional polyacrylamide gel electrophoresis ; Kidney ; Medulla ; Proteomics ; Rat ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The rodent kidney is a target of many xenobiotics and is typified by regionally specific structure and function. This renders distinct regions of the kidney differentially susceptible to toxic exposure and effect. To characterize these differences at the proteome level, protein patterns from male rat kidney cortex and medulla cytosols were examined by two-dimensional electrophoresis (2-DE) and image analysis and prominent proteins identified immunologically or by matrix-assisted laser desorption/ionization - mass spectrometry (MALDI-MS) and electrospray/ionization - tandem mass spectrometry (ESI-MS/MS) sequence tag identification. An average of 727 protein spots were resolved and matched to the cortex cytosol reference pattern, and 716 in the medulla. Of this total, 127 proteins were found to differ in abundance (86 higher in cortex; 41 higher in medulla) (P 〈 0.001). Of those proteins that were detectable in both cortex and medulla, the abundance of 97 differed significantly while 30 proteins were found to be unique to one region or the other (26 in cortex, 4 in medulla). Twenty protein spots were identified and their regional differences are discussed. These results both confirm and expand our understanding of the molecular heterogeneity characterizing structurally and functionally distinct regions of the kidney and serve as a useful foundation for future nephrotoxicologic studies.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150191423
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  • 7
    Electronic Resource
    Electronic Resource
    Metallkomplexe von Farbstoffen. VI.V. Mitteilung: A. Lenz, K. Polborn, W. Beck, Z. Naturforsch. B 49 (1994) 955. Phosphan-Nickel-, Palladium- und Platin-Komplexe sowie Pentamethyl-cyclopentadienyl-Rhodium- und Iridium-Komplexe von Bis(2-hydroxyaryl)azo-FarbstoffenProfessor Helmut Behrens zum 80. Geburtstag gewidmet (1995)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 829-836 
    Details
    ISSN: 0044-2313
    Keywords: Metal complexes ; 2,2′-dihydroxyazoarenes complexes of phosphine nickel, palladium, platinum, pentamethylcyclopentadienyl rhodium, pentamethylcyclopentadienyl iridium ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metal Complexes of Dyes. Phosphine-Nickel, Palladium, Platinum Complexes and Pentamethylcyclopentadienyl Rhodium and Iridium Complexes of 2,2′-DihydroxyazoarenesThe terdentate dianions of 2,2′-dihydroxyazobenzene (L1H), 1-(2-hydroxy-4-nitrophenylazo)-2-naphthol (L2H), 1-(2-hydroxy-5-nitrophenylazo)-2-naphthol (L3H) and 1-phenyl-3-methyl-4-(2-hydroxy-5-nitrophenylazo)-5-pyrazolone (L4H) form with chloro bridged complexes [(R3P)MCl2]2 (M = Pd, Pt; R = Ph, nBu), [(n5-C5Me5)MCl2]2 (M = Rh, Ir) and with (nBu3P)2NiCl2 the metal dye complexes (R3P)ML (M = Ni, Pd, Pt) and (C5Me5)ML (M = Rh, Ir). The structures of (Ph3P)PtL1 and (nBu3P)PdL3 have been determined by X-ray diffraction. For the complexes (n5-C5Me5)ML (M = Rh, Ir) with asymmetric metal centers two diastereoisomers are detected by nmr spectroscopy which points to the „hydrazone“ form of the azo ligand with a pyramidalized N-atom.
    Notes: Die dreizähnigen Dianionen von 2,2′-Dihydroxyazobenzol (L1H2), 1-(2-Hydroxy-4-nitrophenylazo)-2-naphthol (L2H2), 1-(2-Hydroxy-5-nitrophenylazo)-2-naphthol (L3H2) und 1-Phenyl-3-methyl-4-(2-hydroxy-5-nitrophenylazo)-5-pyrazolon (L4H2) bilden mit den chloroverbrückten Komplexen [(R3P)MCl2]2 (M = Pd, Pt; R = Ph, nBu), [(n5-C5Me5)MCl2]2 (M = Rh, Ir) sowie mit (nBu3P)2NiCl2 die Farbstoff-Komplexe (R3P)ML (M = Ni, Pd, Pt) und (n5-C5H5)ML (M = Rh, Ir). Die Strukturen von (Ph3P)PtL1 und (nBu3P)PdL3 wurden röntgenographisch bestimmt. Für die Komplexe (n5-C5Me5)ML (M = Rh, Ir) mit „asymmetrischem“ Metallatom lassen sich NMR-spektroskopisch zwei Diastereoisomere nachweisen, was für den „Hydrazon“-Charakter der Azoliganden mit pyramidalisiertem N-Atom spricht.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19956210522
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  • 8
    Electronic Resource
    Electronic Resource
    Liquid-crystalline side-group polyesters with definite lengths of the main-chain spacers (1992)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 193 (1992), S. 2581-2588 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: New liquid-crystalline polyesters 1 with 4-(phenylazo)azobenzene moities as mesogenic side groups and a polyester backbone structure characterized by a systematic variation of the length of the flexible non-mesogenic main-chain segments were synthesized. The polyesters were investigated by differential scanning calorimetry, polarizing microscopy, miscibility studies and X-ray diffraction. With increasing number of methylene groups in the backbone spacer, the thermal stability of the nematic and/or smectic phases first decreases and then increases.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1992.021931008
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  • 9
    Electronic Resource
    Electronic Resource
    The effect of radical trapping reagents upon formation of poly(α-tetrahydrothiophenio para-xylylene) polyelectrolytes by the wessling soluble precursor method (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 2223-2231 
    Details
    ISSN: 0887-624X
    Keywords: poly(arylene vinylene) ; poly(1,4-phenylene vinylene) ; poly(para-phenylene vinylene) ; para-xylylene ; 1,4-benzoquinodimethane ; radical polymerization ; conducting polymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular weights were studied by gel permeation chromatography of derivatized poly(α-tetrahydrothiophenio para-xylylene) chloride produced by aqueous or methanolic base-induced polymerization of 1,4-bis(tetrahydrothiopheniomethyl) benzene dichloride, both with and without a variety of added polymerization inhibiting agents. Efficient radical scavenging agents such as 2,2,6,6-tetramethylpiperidinoxyl and hydrogen atom donor 2,4,6-tri-tert-butylaniline reduced the degree of polymerization of the reactive α-(tetrahydrothiophenium chloride)-para-xylylene intermediate produced in this chemistry, and in some cases completely suppressed formation of high polymer. These two traps did not affect the equilibrium production of the para-xylylene by UV-Vis spectral analysis; hence they must affect the subsequent polymerization chain propagation steps in the mechanism. Electron spin resonance studies of polymerization in the presence of 0.00025 equiv of TEMPO showed disappearance of the spin label, a result consistent with a radical scavenging process. The results suggest that production of high molecular weight poly(α-tetrahydrothiophenio para-xylylene) chloride proceeds through a radical chain propagation sequence. © 1992 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080301018
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  • 10
    Electronic Resource
    Electronic Resource
    Para-Xylylenes and analogues by base-induced elimination from 1,4-bis-(dialkylsulfoniomethyl)arene salts in poly(1,4-arylene vinylene) synthesis by the wessling soluble precursor method (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 2233-2240 
    Details
    ISSN: 0887-624X
    Keywords: para-xylylenes ; 1,4-benzoquinodimethanes ; conducting polymers ; poly(arylene vinylene)s ; poly(phenylene vinylene)s ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: para-Xylylenes are generated by treatment of various 1,4-bis(dialkylsulfoniomethyl)arene dihalides with base in water, methanol, and aqueous acetonitrile, as shown by UV-Vis spectroscopy. This procedure allows the monitoring of the transient xylylene monomers that yield polyelectrolyte precursor polymers for poly(arylene vinylene)s, formed by variations of the chemistry developed originally by Wessling and co-workers. Alkoxy, alkyl, and halogen ring substituents on the sulfonium salt precursors do not greatly affect the ability to generate and observe the growth and decay of steady-state concentrations of the para-xylylene intermediates. Use of strong resonance-acceptor substituents - such as cyano or nitro - on the ring reduces production of a strong para-xylylene absorption, possibly due to reluctance of the ylides initially formed from the bis-sulfonium salts to eliminate to the xylylenes. By variation of UV-Vis conditions, it was found that use of 20% aqueous acetonitrile rather than water allowed formation of low to modest molecular weight polyelectrolytes in cyano-substituted cases (Mw = 8000-37,000). Use of UV-Vis test experiments should be useful for screening of bis sulfonium salt precursors that may be expected to give high molecular weight polyelectrolytes - in cases where para-xylylene formation is easy - as well as for finding reaction conditions that will optimize polymer formation. © 1992 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080301019
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