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  • calorimetry  (2)
  • nonionic surfactants  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 61 (2000), S. 23-28 
    ISSN: 1572-8943
    Keywords: alcohols ; calorimetry ; complex formation ; cyclodextrins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The complexation of aliphatic alcohols by α- and β-cyclodextrins and their partially methylated derivatives has been studied by means of calorimetric titrations in aqueous solution. The methyl substituents have no pronounced influence upon the complex formation. α-Cyclodextrin and the partially methylated derivative form with only few exceptions more stable than β-cyclodextrin. With increasing chain length of the alcohols the values of the stability constants and reaction enthalpies increase in case of the complex formation with α-cyclodextrin and partially methylated α-cyclodextrin. In contrast the complex formation becomes disfavoured by the reaction entropy with an increasing number of methylene groups. The values of the reaction enthalpies with the β-cyclodextrins are close to zero. Thus the complexation is only favoured by entropic contributions.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 57 (1999), S. 487-491 
    ISSN: 1572-8943
    Keywords: calorimetry ; complex formation ; crown ethers ; guanidinium derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The complexation of urea and some guanidinium derivatives by the ligands 15-crown-5, 18-crown-6, benzo-18-crown-6 and diaza-18-crown-6 in methanol has been studied by means of calorimetric titrations. The complex formation is mainly favored by entropic contributions. The number of solvent molecules released during the complex formation is responsible for the stability of the complexes formed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 37 (2000), S. 231-236 
    ISSN: 1573-1111
    Keywords: cucurbituril ; cyclodextrin ; nonionic surfactants ; complex formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The complexation of nonionicsurfactants and polyethylene glycols by the ligandscucurbituril, α- and β-cyclodextrin wasstudied in aqueous solution. All the examined guestmolecules form complexes with these ligands.Calorimetric titrations were performed to determinedirectly the stability constants and reactionenthalpies. The presence of an aromatic part innonionic surfactants leads to more stable complexeswith β-cyclodextrin than with the other ligands.If the surfactants contain no benzene group, theinteractions with α-cyclodextrin are strongercompared to other ligands. The chain length of thepolyethylene glycols has only an influence upon thevalues of the reaction enthalpy in the case ofα-cyclodextrin.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 33 (1999), S. 233-241 
    ISSN: 1573-1111
    Keywords: cyclodextrins ; nonionic surfactants ; complex formation ; fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The complex formation between some nonionic surfactants and α-, β- and γ-cyclodextrin was studied by fluorescence measurements. The relative fluorescence intensity of a solute containing a nonionic surfactant at a constant concentration far below the critical micelle concentration (CMC) are enhanced by the addition of cyclodextrins. Non linear type equations were derived to obtain stability constants by fluorescence measurements for inclusion complexes formed between cyclodextrins and the nonionic surfactants. In most cases 1 : 1- and 2 : 1-complexes (ratio of cyclodextrin to surfactant) are formed.
    Type of Medium: Electronic Resource
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