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  • Chemistry  (27)
  • Polysilane  (2)
  • Adolescents  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Cigarette withdrawal symptoms in adolescent smokers (1986)
    Springer
    Psychopharmacology 90 (1986), S. 533-536 
    Details
    ISSN: 1432-2072
    Keywords: Cigarette smoking ; Withdrawal ; Adolescents ; Cotinine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract One hundred and sixteen female adolescent smokers were asked about withdrawal symptoms experienced during past attempts to give up smoking for good. Sixty-three percent reported difficulties during abstinence of the kind experienced by adult smokers. Daily smokers were more likely to report withdrawal effects than non-daily smokers (74% versus 47%, P〈0.005). Reported experience of withdrawal symptoms was positively related to self-reports of cigarette consumption and depth of inhalation and nicotine intake as indexed by salivary cotinine concentrations. Reported occurrence of at least one withdrawal effect correlated positively with nicotine intake after controlling for behavioural variables. Our results indicate that teenage smokers are likely to suffer withdrawal symptoms when they try to give up. Behavioural factors and expectations based on observations of adults may have played a part in their experience of withdrawal, but it is also likely that pharmacological factors are implicated even at this early stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00174074
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  • 2
    Electronic Resource
    Electronic Resource
    Properties of some polysilane polymers: (n-PrSiMe) n , (i-PrSiMe) n , and (sec-BuSiMe) n (1995)
    Springer
    Journal of inorganic and organometallic polymers and materials 5 (1995), S. 31-42 
    Details
    ISSN: 1572-8870
    Keywords: Polysilane ; nematic mesophase ; liquid crystal ; isotopic phase ; thermochromic transition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Three polysilane polymers, (n-PrSiMe) n , (i-PrSiMe) n , and (sec-BuSiMe) n , were synthesized and characterized by DSC. UV spectroscopy, wide-angle X-ray diffraction, and optical microscopy, all at variable temperatures. The known thermochromic transition of (n-PrSiMe) n at ∼48 C is associated with a change from an orthorhombic to an isotropic phase. (i-PrSiMe) n was examned as an insoluble and soluble (lowM w) fraction, both existing mainly in an orthohombic lattice at room temperature. (sec-BuSiMe) n has a mesophase structure at 25 C, undergoes a weak endothermic transition to a second (nematic) mesophase near 65 C, and becomes isotropic at ∼160 C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01157521
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of alternating silane copolymers: (Me2Si−R2Si−Me2Si) n (1995)
    Springer
    Journal of inorganic and organometallic polymers and materials 5 (1995), S. 217-236 
    Details
    ISSN: 1572-8870
    Keywords: Polysilane ; NMR ; pyrolysis ; randomization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Bimodal molecular weight distributions of alternating copolymers of the type (Me2Si−R2Si−SiMe2) n , where R=hexyl and butyl, were obtained by polymerization of BrSiMe2−R2Si−Me2SiBr, using the Wurtz coupling method. Analysis of the samples by pyrolysis GC MS and solution29Si NMR indicated that some randomization occurred, due to cleavage of the original Si−Si bonds in the monomer. The extent of randomization was significantly greater in the high molecular weight fractions. Based on the nature of the rings from the py MGC/MS traces and the number on nonads found in the29Si spectra, two types of randomization processes have been proposed, involving backbiting followed by (1) ring expulsion or (2) redistribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01057894
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  • 4
    Electronic Resource
    Electronic Resource
    29Si nuclear magnetic resonance of dimethyl and phenylmethyl containing polysilanes (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 701-712 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 29Si-NMR spectra are reported for poly(methylphenylsilylene), 1, poly(1,1,2-trimethyl-2-phenyldisilene) 2, two samples of poly(dimethylsilylene-co-phenylmethylsilylene), 3a and 3b, and poly(phenylmethylsilylene-co-n-hexylmethylsilylene), 4. The spectra of 3a, 3b, and 4 indicate that these polymers contain blocklike regions with considerable segregation of RMeSi and PhMeSi groups. The spectrum of 2 shows no evidence for stereospecific polymerization. The preparation of 2 from 1,1,2-trimethyl-2-phenyldichlorosilane is also described.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1988.080260303
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  • 5
    Electronic Resource
    Electronic Resource
    29Si nuclear magnetic resonance of dialkylpolysilanes (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 713-720 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The silicon-29 nuclear magnetic resonance spectra of a number of dialky- and alkylmethylpoly-silanes are reported. Polysilanes composed of asymmetrically substituted silylenes (i.e., alkylmethylsilylenes) exhibited very broad resonance lines attributed to diastereomeric chemical shifts of stereogenic silylenes alpha and beta to the observed nucles Symmetrically substituted polysilanes showed a single narrow peak. The 29Si chemical shifts for these polysilanes decrease with increasing steric bulk of the substituents, varying inversely with the electronic excitation energy.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1988.080260304
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  • 6
    Electronic Resource
    Electronic Resource
    Studies of silicon-nitrogen ring formation from tetrachlorodisilanesDedicated to Prof. Adrian Gibbs Brook, father of the silicon = carbon double bond. (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 5 (1994), S. 205-214 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The addition of n equiv of MesNHLi (n = 1, 2, 3, 4) and m equiv of 12-crown-4 (m = 0.1, 1, 2, 3, 4) to (RsiCl2)2 (R = Mesityl; t-Butyl) in THF at -78°C resulted in higher yields and improved selectivities of cyclodisilazanes and azadisilacyclopropanes. The reaction of 2 equiv of MesNDLi with (MesSiCl2)2 (I) yielded cis-2-chloro-1,2,3,4-tetramestylcyclodisilazane (2a) with 95% Si—H deuteration. 2a was quantitatively chlorinated with retention of stereochemistry by N-chlorosuccinimide to give the cis dichlorocyclodisilazane (3). Variable-temperature 1H NMR studies from -70°C to 25°C in d8-THF were performed on 1, 2a, 2b, and 3. 1 exhibited little variation throughout the temperature range, whereas 2a, 2b, and 3 showed several rotational isomers. trans-2,3-Bis(mesitylamino)-1,2,3-trimesitylazadisilacyclopropane was shown to isomerize to the cis isomer in the presence of n-BuLi or MesNHLi. The molecular structures of 1 and 3 were determined by X-ray crystallography. Compound 1 crystallized in the monoclinic space group P21/c, with cell parameters a = 16.599(2) Å b = 14.633(2) Å, c = 16.945(2) Å, β = 92.044(13)°, V = 4113.1(8) Å3, Z = 8, d (calcd) = 1.409 g/cm3, and R = 6.88%. Compound 3 ° C6H6 crystallized in the orthorhombic space group Pbca, with cell parameters a = 17.906(4) Å, b = 13.918(3) Å, c = 31.700(6) Å, V = 7900(3) Å3, Z = 8, d (calcd) = 1.194 g/cm3, and R = 7.52%.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hc.520050304
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  • 7
    Electronic Resource
    Electronic Resource
    The wonderful world of organosilicon chemistryAs presented at the Ninth International Symposium on Organosilicon Chemistry, Edinburgh (scotland); July 16-20, 1990. (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 2 (1991), S. 335-355 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hc.520020216
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  • 8
    Electronic Resource
    Electronic Resource
    Crystallographic analysis of thermochromic, unsolvated tetramesityldisilene at 173 K and 295 K (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 1 (1990), S. 1-7 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: X-ray crystal structure determinations of tetramesityldisilene (1) at 295 K, where it is bright orange, and at 173 K, where it is pale yellow, were experimentally equivalent. The thermochromism of 1, therefore, is not due to changes in conformation; a vibrational origin is considered. The crystal structure of unsolvated 1 differs substantially from that of the toluene solvate (1·C7H8) because of different crystal packing of the two forms. These two solid-state structures are compared with those of four other disilenes.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hc.520010102
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  • 9
    Electronic Resource
    Electronic Resource
    Synthetic and Structural Studies of 1-Sila-2,5-diaryltetrazenes (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1579-1583 
    Details
    ISSN: 0009-2940
    Keywords: Silatetrazenes ; Nitrogen-silicon ring systems ; Bissilylamines ; Silicon-29 solid state NMR ; Aryl azides ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction between aryl azides and lithiated aryl amines leads to tetrazenes 3 and 9 which contain a chain of four nitrogen atoms. Reaction with different halosilanes gives the cyclic silatetrazenes 10, 12, and 15 where substitutents on the silicon vary form alkyl to hydrogen and chlorine atoms. The structures of 10, 12, and 15 in the solid state are reported. Variation of the solvent and the Lewis acidity of the halosilane influence the ratio of silatetrazene to side products, bissilyated amines. These effects are studied for different halosilanes.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971301105
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  • 10
    Electronic Resource
    Electronic Resource
    Homologe Reihe cyclischer Polysilane von (Me2Si)5 bis (Me2Si)35Professor Gerhard Fritz zum 60. Geburtstag gewidmetCyclische Polysilane, 14. Mitteilung. Diese Arbeit wurde von der U. S. Air Force of Scientific Research unterstützt (Grant AF-AFOSR-78-3570). - 13. Mitteilung: [3]. (1979)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 91 (1979), S. 1022-1023 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19790911228
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