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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 93 (1989), S. 6454-6458 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 91 (1987), S. 2005-2006 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 26 (1996), S. 219-232 
    ISSN: 1573-1111
    Keywords: γ-Cyclodextrin ; dimerization ; viologen ; inclusion complexes ; association constants ; spectroelectrochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effects of cyclodextrins (CDs) on the monomer-dimer equilibria of 1,1′-dialkylviologen radical cations (Cn Cn V.+ :n = 1–5) and one-electron reduced 1,1′-bis(3-sulfopropyl)viologen (SPV) were investigated spectroelectrochemically. The dimerization is enhanced upon addition ofγ-CD, while the addition ofα-CD andβ-CD suppresses the dimerization. This is attributed to the stabilization of dimers by the inclusion of the dimer in the cavity ofγ-CD From the dependence of the apparent dimerization constants (K D ′ ) on the concentration ofγ-CD the association constants of the monomer (K C1) and dimer (K C2) withγ-γ-CD were determined. TheK C1 value increases slightly, from 5 M−1 forn = 1 to 35 M−1 forn = 5, as the length of the alkyl substituents of viologen increases. TheK C2 value depends strongly on the alkyl substituents giving the smallest value of 85 M−1 for (SPV.−)2 and the largest one of 3500 M−1 for (C4C4V.+)2. These results, together with the difference in UV-vis absorption spectra obtained in the absence and in the presence ofγ-CD, suggest that the alkyl substituents and part of the bipyridine ring of viologen radicals are included in theγ-CD cavity forming dimers in which the bipyridine rings are stacked at an oblique angle.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 27 (1997), S. 41-48 
    ISSN: 1573-1111
    Keywords: reduction ; β-cyclodextrin ; asymmetric induction ; sodium borohydride ; enantioselectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Asymmetric reduction of various prochiral ketones was achieved with sodium borohydride utilizing β-CD or its derivative, mono-6-deoxy-6-[N-(2-aminoethyl)]amino-β-CD (β-CD-en) as a chiral template. It was found that pre-equilibrium between ketone and β-CD derivative and low reaction temperature increase asymmetric induction. The extent of asymmetric induction and the absolute configuration of the resulting secondary alcohols are highly dependent upon the nature of the ketones and also β-CD derivatives. A mechanistic scheme is suggested to explain the dependency.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 36 (2000), S. 343-354 
    ISSN: 1573-1111
    Keywords: modified β-cyclodextrin ; hydrolysis ; catalysis ; enantioselectivity ; poly(allylamine)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Effects of β-cyclodextrin (β-CD) 1and its derivatives 2–7 on the deacylationreaction of p-nitrophenyl (R or S)-α-methoxyphenylacetatewere studied. Theβ-CD derivatives used were6-α-D-glucosyl-β-CD 2, sulfatedβ-CD (7–11 sulfate groups/CD ring) 3,dimethylated β-CD 4, carboxymethylatedβ-CD (3.5 carboxymethyl groups/CD ring) 5,2-tri(2-hydroxypropyl)-β-CD 6, andβ-CD appended on poly(allylamine) 7. Therate constant (kψ CD) of thesubstrate/β-CD complexes and the formationconstants (K) of the complexes were determinedfrom the dependence of the pseudo-first order rateconstants of the deacylation reaction on theconcentration of β-CDs. The order ofkψ CD for the R-enantiomer at pH8.0 is 4≪5H2O3≅ 6 1 ≅ 2 ≪ 7, whilethat for the S-enantiomer is 4 ≪ 5 ≅ 6H2O ≅ 1 ≅ 2 3 ≪ 7: H2O denotes the rate in theabsence of β-CDs. The order of K values is3 7 6 ≅ 2 ≅ 1 4 5. This work indicates that, though thesecondary hydroxyl groups of β-CD play criticalroles in the deacylation reactions of the esterscomplexed with β-CDs, the reactivity of theester/β-CD complexes depends highly on thenature of the substituents at the secondary face ofβ-CD. It also suggests that the substratesinserted from the secondary side as well as theprimary side of β-CD of poly(allylamine)-boundβ-CD undergo the reaction by attack of aminogroups on the polymer chain.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-1111
    Keywords: β-Cyclodextrin ; inclusion complexes ; fluorescence ; aminostyryl dyes ; association constants ; fluorescent-probe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 2-(or4-)-[4-(Dimethylamino)styryl]-1-methylpyridinium iodides (2-ASP and 4-ASP) form 1∶1 inclusion complexes withβ-cyclodextrin (β-CD). The association constant is about 1000 M−1 for both dyes in aqueous solution at 25°C. The complexation results in a 7.6- and 4.9-fold increase in the fluorescence intensities of 2-ASP and 4-ASP, respectively. The formation of inclusion complexes ofn-alkylamines (n=4–10),n-alkylammonium ions (n=4–10),n-alkyl alcohols (n=4–9), andn-alkyltrimethylammonium bromides (C n TAB:n=12, 14, 16) with β-CD was studied by a fluorescent-probe method using 2-ASP as a probe. The association constantsK were obtained from nonlinear least-square regression analysis of the fluorescence titration data. The logarithm of the 1∶1 association constants varies approximately linearly with the number of carbon atoms (n c) of the alkyl chain up ton c=7 and then the dependence of logK onn c is less pronounced for longer alkyl chains: for C n TAB, 1∶2 complexation was also observed. Combining the present result with a previous work [15], we found that the increasing order of stability of β-CD complexes of amphiphilic molecules with the same hydrocarbon tail but different head groups is ammonium 〈 sulfonate 〈 alcohol ≅ amine 〈 sulfate. The association constants obtained from this method are compared with those given by other investigators and the discrepancies are discussed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 2129-2139 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polyaniline perchlorate (PAP) was synthesized by electrochemical oxidation from 0.2 M aniline in acetonitrile solution containing 0.1 M tetraethylammonium perchlorate as supporting electrolyte. From polarographic and cyclic voltammetry results, the values of the half-wave potential (E1/2), transfer coefficient (α), and number of electrons related to the electrode reaction (n) were calculated to be 825 mV, 0.894, and 1, respectively. The morphology of the PAP film was observed by using an SEM analyzer. From thermal analysis of the PAP sample, the reaction rate (R) for its thermal decomposition was obtained from the TGA result and a exothermic peak at 330°C was also observed in the DSC curve. The electrical conductivity of the PAP pellet was measured at temperatures from -170 to 25°C. From a plot of conductivity vs. 1/T, the activation energy (Ea) was obtained to be 0.14 eV. The conduction mechanism in a pressed pellet of PAP is suggested to be electronic hopping conduction. The values of the ESR parameters were calculated from an ESR curve for PAP at room temperature.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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