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  • 1
    Electronic Resource
    Electronic Resource
    Towards New Iron(III) Chelators: Synthesis and Complexing Ability of a Water-Soluble Tripodal Ligand Based on 2,2′-Dihydroxybiphenyl Subunits (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 613-619 
    Details
    ISSN: 1434-1948
    Keywords: Dihydroxybiphenyl ; Iron chelation ; Formation constants ; Protonation constants ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new water-soluble iron(III) sequestering agent has been designed. The tris-bidentate tripodal ligand consists of three 2,2′-dihydroxybiphenyl subunits connected via amide linkages at their meta (4-) positions to a framework of the “tren” type. The key step of the synthesis involves the coupling of suitably substituted monophenyl moieties in order to obtain the biphenyl precursor. The deprotonation constants of the ligand, and the formation and deprotonation constants of the FeIII complex have been determined from potentiometric and spectrophotometric measurements. The results are compared with those of a previously described homologous ligand in which the chelating subunits are attached to the tren framework via the ortho (3-) position of the biphenyl rather than the 4-position.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Carbon-13 nuclear magnetic resonance spectroscopy of methyl-substituted piperidines and their hydrochloride salts (1978)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 11 (1978), S. 418-423 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbon-13 chemical shifts and 1J(CH) coupling constants of piperidine, 4-t-butylpiperidine, five C-methyl substituted piperidines and of the corresponding N-methyl compounds have been measured. These NMR parameters have also been determined for the fourteen corresponding hydrochlorides. The N-methyl-C-methyl piperidinium salts showed two stereoisomers on the positive nitrogen atom. The effect of protonation is discussed in relation to charge and steric effects and the methyl substituent effects are compared with those of methyl-substituted cyclohexanes. Deviations from the general tendencies in the series are correlated with changes in ring conformations around the highly crowded substituted carbons.
    Additional Material: 9 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270110811
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  • 3
    Electronic Resource
    Electronic Resource
    Carbon-13 NMR of oxygenated derivatives of polyoxyethylenes (1982)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 19 (1982), S. 102-104 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 13C NMR spectra of several oligo(oxyethylene) glycols and of their derivatives obtained from oxidative cleavage were studied. Assignments are proposed and the 13C chemical shifts recalculated from sets of parameters obtained for the substituents on the parent structure, —CH2—CH2—O—.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270190212
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  • 4
    Electronic Resource
    Electronic Resource
    19F and 1H NMR of aldimines of fluoroamino acids with pyridoxal-5′-phosphate (1981)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 16 (1981), S. 129-132 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H and 19F NMR spectra were obtained for six Schiff bases (aldimines) formed by pyridoxal-5′-phosphate (PLP) with four fluorinated or their two parent non-fluorinated α-amino acids (phenylalanine and α-aminobutyric acid). pKA Values were derived from 1H and 19F titration curves. The imine nitrogen of the aldimines is very basic (∼13) and sensitive to the electron withdrawing effect of fluorine. The pyridine nitrogen is less basic in the aldimines (∼7) than in PLP (8.12) and is less sensitive to the electron withdrawing effect of the fluorine than is the imine nitrogen. The phosphate group has a pK in the same range (∼6) and the chemical shifts of some nuclei are sensitive to both pK values. Protonation of the aldimine causes the 1H signal to shift downfield at the methyl protons of the pyridine ring and at the aldehydic proton of the aldimine for the high pK value (except for the aldimines prepared from the β-fluorophenylalanine), but upfield at the aromatic proton and at the aldehydic proton of the aldimine for the low pK. Protonation of the aldimine causes the 19F signal of an aryl fluorine to shift downfield but gives an upfield shift at a β-fluorine. These data are related to the highly conjugated electronic structure of the Schiff bases.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270160214
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  • 5
    Electronic Resource
    Electronic Resource
    Conformational studies on 2-fluoro-1,2-disubstituted ethanes by NMR spectroscopy. Influence of electronegativity on vicinal proton-proton and fluorine-proton coupling constants (1983)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 21 (1983), S. 361-366 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The analysis of the ABKX spectra of thirteen compounds of the series RC(H-K)(F-X)C(H-A)(H-B)X gave the four vicinal proton-proton and fluorine-proton coupling constants. These coupling constants of conformationally mobile structures were used (i) to calculate the populations of the rotational states of the —CHF—CH2— bond, (ii) to calculate the vicinal trans proton-proton J(HH)t and gauche and trans fluorine-proton coupling constants J(FH)g and J(FH)t and (iii) to give the unambiguous assignment of protons H-A and H-B. The dependence of the gauche and trans coupling constants with substituent electronegativity is explored. The results extend known correlations towards smaller electronegativity values. More quantitatively, the results and those in the literature, excluding those where deformations of torsional or bond angles occur, give a good fit of the data: a linear fit for J(HH)t = 15.0-0.77 Σ(ΔE), an exponential fit for J(FH)g = 15.35 exp [-0.266 Σ (ΔE)] and a linear fit for J(FH)t = 65.75 - 7.52 Σ (ΔE), where Σ (ΔE) is the sum of the electronegativity difference between hydrogen and the six atoms or groups on the CH—CF fragment.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/omr.1270210605
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  • 6
    Electronic Resource
    Electronic Resource
    Quantitative 2D EXSY and Dynamic 19F-NMR Studies of the Dynamic Behaviour of the Bidentate Chelate Complex Ga(fox)3 (fox = 5-fluoro-8-hydroxyquinoline) (2000)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 2000 (2000), S. 545-550 
    Details
    ISSN: 1434-1948
    Keywords: Coordination chemistry ; Gallium(III) ; Dynamik 19F NMR ; EXSY ; Kinetics of ligand exchange ; Bailar and Rây-Dutt mechanisms ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rates of intramolecular rearrangement of the meridional isomer of the metal tris-chelate complex [Ga(fox)3, fox = 5-fluoro-8-hydroxyquinoline] in DMF solution were measured using 1D NMR line shape analysis and 2D EXSY spectra. The rates of exchange kab, kbc and kac between the three non-equivalent ligands a, b and c were determined. The values of the activation parameters were obtained. ΔH
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Three-bond carbon-fluorine coupling constants in substituted 3-fluoropropanes and 3-fluoropropanoates (1986)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 24 (1986), S. 337-342 
    Details
    ISSN: 0749-1581
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three-bond carbon-fluorine coupling constants of 32 substituted 3-fluoropropanes and 3-fluoropropanoates were measured. From these values and from those of other alicyclic compounds already known in the literature, it can be established that the influence of molecular parameters on 3J(FC) depends on the nature of the coupled carbon. When this carbon belongs to an alkyl group, the main molecular parameter is the dihedral angle [J(FC)g = 1.2 Hz and J(FC)t = 11.2 Hz]. When the carbon belongs to a carbethoxy group, more complex effects are observed: for one series the main parameter is the dihedral angle [J(FC)g = 0 Hz and J(FC)t = 20 Hz], and for other series the electronegativity and orientation of substituents particularly influence J(FC)g. Conversely, the diastereoisomers can be unambiguously identified from the 3J(HH), 3J(FH) and 3J(FC) values of both diastereoisomers.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260240413
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  • 8
    Electronic Resource
    Electronic Resource
    Configurational assignment of β-fluoro-β-phenylamines using 1H and 19F NMR (1988)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 26 (1988), S. 621-624 
    Details
    ISSN: 0749-1581
    Keywords: 1H NMR ; 19F NMR ; Configurational assignment ; β-Fluoro-β-phenylamines ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1H and 19F NMR parameters [δH-α, δH-β, δF, 3J(HH) and 3J(FH)] of β-fluoro-β-phenylamines of the two series PhCHFCH2NR1R2 and PhCHFCH(R)-NR1R2 in CDCl3 (amine form) and in CD3OD (protonated amine form) and those of the corresponding β-hydroxy-β-phenylamines were measured. It is shown that for the protonated amines the predominant conformation is that in which the ammonium group is antiperiplanar to the phenyl group, especially for tertiary amines. Assignment of the diastereoisomers of the PhCHFCHRNR1R2 series can be made with the NMR parameters of the protonated amines: high (low) 3J(HH) values, low (high) 3J(FH) values, 19F chemical shifts to high (low) frequency are those for the threo (erythro) isomers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260260718
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  • 9
    Electronic Resource
    Electronic Resource
    Protonated XH heteroatom (X = O, N, S) analysis in oil fractions from morocco oil-shale using 29Si multiple-pulse NMR (1991)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 29 (1991), S. 576-579 
    Details
    ISSN: 0749-1581
    Keywords: 29Si NMR ; Oil fractions ; Protonated heteroatom (O, N, S) content ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The characterization and determination of the protonated heteroatom content of the XH type (X = O, N, S) in oil fractions was carried out using 29Si NMR on silylated derivatives of the heteroatomic compounds. The analysis was achieved on a mixture of standard compounds and on two oil fractions from Morocco oil-shale: asphaltenes and the aromatic and polar components.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260290607
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