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  • complex formation  (7)
  • calorimetry  (2)
  • 1
    Electronic Resource
    Electronic Resource
    The complexation of alkaline cations by crown ethers and cryptands in acetone (1994)
    Springer
    Journal of solution chemistry 23 (1994), S. 569-577 
    Details
    ISSN: 1572-8927
    Keywords: Acetone ; crown ethers ; cryptands ; complex formation ; ion pairs ; alkali metal ions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Stability constants and thermodynamic values for the complex formation of alkali ions by crown ethers, diaza crown ethers and cryptands have been measured by means of potentiometric and calorimetric titrations in acetone as solvent. The interactions between the ligands and solvent molecules play an important role for the complex formation. Cryptands form the most stable complexes with alkali ions if inclusion complexes are formed. Even in the case that the salts are not completely dissociated in acetone the presence of ion pairs does not influence the calculated values of the stability constants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00972745
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  • 2
    Electronic Resource
    Electronic Resource
    Complexation of Aliphatic Alcohols by α- and β-Cyclodextrins and their Partial Methylated Derivatives in Aqueous Solution (2000)
    Springer
    Journal of thermal analysis and calorimetry 61 (2000), S. 23-28 
    Details
    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
    URL: http://dx.doi.org/10.1023/A:1010140019557
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  • 3
    Electronic Resource
    Electronic Resource
    Complex Formation Between Crown Ethers and Urea and Some Guanidinium Derivatives in Methanol (1999)
    Springer
    Journal of thermal analysis and calorimetry 57 (1999), S. 487-491 
    Details
    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
    URL: http://dx.doi.org/10.1023/A:1010120108944
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  • 4
    Electronic Resource
    Electronic Resource
    Cucurbituril and β-Cyclodextrin as Hosts for the Complexation of Organic Dyes (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 29 (1997), S. 167-174 
    Details
    ISSN: 1573-1111
    Keywords: Cucurbituril ; β-cyclodextrin ; dye molecules ; complex formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The complexation of neutral organic molecules by cucurbituril andβ-cyclodextrin in formic acid was studied by means ofspectrophotometric titrations. In the case of β-cyclodextrin thecomposition of the solvent has almost no influence upon the stability of thecomplexes formed. This situation is completely different for cucurbituril.Due to its interactions with protons the measured stability constants of thecomplexes formed with organic molecules increase with decreasing acidconcentration. At low acid concentrations cucurbituril forms more stablecomplexes with organic molecules than β-cyclodextrin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007981816611
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  • 5
    Electronic Resource
    Electronic Resource
    Cucurbituril and α- and β-Cyclodextrins as Ligands for the Complexation of Nonionic Surfactants and Polyethyleneglycols in Aqueous Solutions (2000)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 37 (2000), S. 231-236 
    Details
    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
    URL: http://dx.doi.org/10.1023/A:1008148831359
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  • 6
    Electronic Resource
    Electronic Resource
    The Interactions Between Nonionic Surfactants and Cyclodextrins Studied by Fluorescence Measurements (1999)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 33 (1999), S. 233-241 
    Details
    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
    URL: http://dx.doi.org/10.1023/A:1008069213946
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  • 7
    Electronic Resource
    Electronic Resource
    The Interpretation of Thermodynamic Data for the Complex Formation of Cations with Crown Ethers and Cryptands. Part I: The Reaction Entropy (2000)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 38 (2000), S. 85-97 
    Details
    ISSN: 1573-1111
    Keywords: crown ethers ; cryptands ; complex formation ; reaction entropy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The complex formation between cationsand crown ethers or cryptands is influenced byenthalpic and entropic contributions. The solvation ofcations and ligands plays an important role andinfluences both thermodynamic parameters. Changes insolvation and their influence upon the reactionentropy is discussed in detail for some selectedreactions in different solvents. Other contributionse.g., from the deformation of the ligands areeliminated. Thus, the results obtained are valid forall complexation reactions between cations andmacrocyclic and macrobicyclic ligands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008136403647
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