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  • Analytical Chemistry and Spectroscopy  (6)
  • 1990-1994  (2)
  • 1985-1989  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Reduction processes in the fast atom bombardment mass spectrometry of sulfonyl esters of diazonaphthalenones (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 23 (1988), S. 443-452 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Orthoquinone diazides, which are widely used in microlithography, have attracted considerable attention, especially in terms of their application in the production of high-contrast resists. Previous electron impact mass spectrometric results have confirmed that the primary fragmentation process of these compounds is the elimination of N2 to form an indenoketene ion. This is analogous to the photodecomposition pathway which makes them effective in the lithographic process. Those results also revealed the occurrence of an alternative process, which involves a two-hydrogen reduction of the intermediate species formed prior to conversion to the ketene. The present study investigates the behaviour of the orthoquinone diazides when there is an abundance of protons available to form the reduction product. Several different types of diazonaphthalenone sulfonyl esters, ranging in complexity from the monosubstituted phenol esters to disubstituted dihydroxybenzophenones, were examined using fast atom bombardment mass spectrometry. Although reduction was the primary process in the hydrogen-rich matrices, the extent of reduction was characteristic of the particular isomer as well as the matrix used.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210230604
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  • 2
    Electronic Resource
    Electronic Resource
    1H and 13C NMR study of the adsorption of alcohols on charcoals with various pore structuresProject supported by National Natural Science Foundation of China. (1989)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 27 (1989), S. 987-991 
    Details
    ISSN: 0749-1581
    Keywords: Adsorption NMR ; Charcoal ; Alcohols ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A 1H NMR study of methyl, ethyl, n-propyl, isopropyl and allyl alcohols adsorbed on charcoals with various pore structures showed that the adsorption mechanism is by capillary condensation in pores with radii smaller than 30 Å, and by mono-/multi-layer adsorption on the solid surface of pores with larger radii. This mechanism is identical with that of adsorbed hydrocarbons. The 13C NMR parameters suggest that the adsorbed alcohols are preferentially oriented in the monolayer, with the methyl groups bonded to the solid surface. Longer chain alcohols are bent in capillaries with radii smaller than 10 Å. The broadening of the 13C resonances was partly eliminated in magic angle spinning experiments by using a spinning rate of 1.5-1.8 kHz.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260271015
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  • 3
    Electronic Resource
    Electronic Resource
    Investigation of the behaviour of propylene oxide in water by 1H NMR measurements (1989)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 27 (1989), S. 57-60 
    Details
    ISSN: 0749-1581
    Keywords: 1H NMR ; Propylene oxide-water ; Nature of hydrogen bond ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As an electron donor solvent, propylene oxide (PO) forms a hydrogen bond with water in their binary mixture. The repulsion produced by the electrostatic field from the PO…HOH hydrogen bond forces the protons and methyl group of PO to bend away from the —O— group and results in the approach of these protons into the plane of the three-membered ring. Consequently, they experience a stronger paramagnetic field from the ring current and their 1H resonances shift to a lower field. The changes of the H—C—H angle and H—C—C—H dihedral angles of PO in water cause the geminal coupling constant and the vicinal cis coupling constant to decrease and the vicinal trans coupling constant to increase.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260270110
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  • 4
    Electronic Resource
    Electronic Resource
    Structure determination of a new saponin from the plant Alphitonia zizyphoides by NMR spectroscopy (1993)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 31 (1993), S. 472-480 
    Details
    ISSN: 0749-1581
    Keywords: Alphitonia zizyphoides ; Saponin ; 2D NMR ; INADEQUATE ; Molecular structure ; Computerized spectral analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High-field NMR experiments, including the 2D INADEQUATE technique coupled with a computerized spectral analysis, were used to determine the full structure of a new saponin extracted from a plant (Alphitonia zizyphoides) found in the Samoan rain forests. The saponin, which shows significant pharmacological activity, consists of an aglycone framework of six rings (three saturated six-membered rings, two oxygen-containing five-membered rings and a five-membered carbon ring) to which are attached four sugar units and a six-carbon side-chain. The INADEQUATE experiment, which was carried out on 60 mg of sample, provided absolute confirmation of the assignments for 35 of the possible 53 C—C bonds from the 13C-13C connectivities.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260310511
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  • 5
    Electronic Resource
    Electronic Resource
    13C, 17O and 1H NMR study of the protonation of acetone in water (1987)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 25 (1987), S. 575-578 
    Details
    ISSN: 0749-1581
    Keywords: Acetone-water ; Multinuclear NMR ; Protonation ; Water structure ; 1H NMR of water ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The protonation of acetone in water for a wide range of compositions of the binary mixture was studied by multinuclear NMR spectroscopy. Formation constants (K1 and K2) and 13C, 17O and 1H chemical shifts of the 1:1 and 1:2 complexes were evaluated. The correlation of the 1H chemical shift of uncombined water with its concentration, Δ0H2O = A + B In [H2O]eq, recently derived for the trimethyl phosphate-water system, was verified. A measure of the fraction of monomer species existing in the uncombined water at each composition was obtained. The results are discussed with respect to the structure of water.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260250705
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  • 6
    Electronic Resource
    Electronic Resource
    Surfactant-aided surface enhanced Raman scattering of Ni(II) tetrasulphonate phthalocyanine in silver sol (1991)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 22 (1991), S. 597-600 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Surface enhanced Raman scattering (SERS) has been used to investigate the structure, surface reaction and enhancement mechanism of adsorbed molecules on metal surfaces. However, a major limitation has been having to choose the molecules with functional groups capable of adsorbing onto metal surfaces. We report here SERS of Ni(II) tetrasulphonate phthalocyanine (Ni(II)PCS) as a result of introducing cationic surfactants like CTAB or CTAC. Ni(II)PCS does not adsorb onto a silver surface by itself and consequently does not show any SERS effect. The cationic surfactants employed here have functional groups to adsorb onto a silver surface and simultaneously interact with anionic sulphonate groups of Ni(II)PCS. Surfactant-aided SERS would expand the range of SERS application to molecules which are not able to adsorb onto metal surfaces by themselves.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250221010
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