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  • Inclusion complexes  (2)
  • electrolytic conductance  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Conductance Study of the Binding of K+ by Dibenzo-pyridino-18-crown-6 and 1,10-N,N′-didecyl-diaza-18-crown-6 in Acetonitrile (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 29 (1997), S. 15-22 
    Details
    ISSN: 1573-1111
    Keywords: Inclusion complexes ; stability constants ; crown ethers ; aza crown ethers ; potassium ion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The binding of K+ by dibenzo-pyridino-18-crown-6 (B2-py-18-C-6) and1,10-N,N′-didecyl-diaza-18-crown-6 (22-DD) has been studiedconductometrically at 10, 15, 20 and 25 °C in acetonitrile. Thecomplexes formed were assumed to have 1 : 1 stoichiometry. The complexes ofK+ with 18-crown-6 (18-C-6) and dibenzo-18-crown-6 (B2-18-C-6) were alsostudied for comparison purposes. The stability constant, K, of a givencomplex and its molar conductance, Λ c, were obtained by subjectingthe conductance data to a non-linear least-squares curve fitting procedure.The values of the enthalpy change, ΔH, the entropy change, ΔSand the Gibbs free energy, ΔG, associated with the formation of the 1: 1 complexes were derived and compared with relevant literature data. Thevalues of ΔG at 25 °C indicate that the binding capacity of thefour macrocycles follows the order 18-C-6 〉 22-DD 〉 B2-18-C-6 〉B2-py-18-C-6. The difference between the molar ionic conductance of the freeK+ cation and that of the bound cation, KL+, was estimated and the trend insuch differences correlates with the molecular size of the macrocycle, L.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007923632191
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A thermodynamic study of the inclusion processes of α- andβ-cyclodextrins with the acid forms of methyl orange and methyl yellow (1992)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 14 (1992), S. 195-204 
    Details
    ISSN: 1573-1111
    Keywords: Inclusion complexes ; stability constants ; cyclodextrins ; methyl orange ; methyl yellow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of temperature on the UV-visible spectra of the acid forms of methyl orange and methyl yellow in the presence of α- andβ-cyclodextrins was analysed in terms of 1 : 1 inclusion processes. Three inclusion processes were considered for each azo dye/cyclodextrin system. The processes are the apparent inclusion process, the ammonium inclusion process, and the azonium inclusion process. The values of ΔH 0 and ΔS 0 are reported for each process. The inclusion complexes of the ammonium tautomer are more stable than those of the azonium tautomer and α-cyclodextrin inclusion complexes are more stable than those ofβ-cyclodextrin. The inclusion processes resulted in a shift in the position of the tautomeric equilibrium of an azo dye. A significant color fading was observed in α-cyclodextrin/methyl yellow solutions. No measurable changes in the absorbances were observed in the case of azo dye solutions containing γ-cyclodextrin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01045980
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    A conductance study of the binding of benzo-15-crown-5 with alkali cations in acetonitrile (1988)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 6 (1988), S. 583-591 
    Details
    ISSN: 1573-1111
    Keywords: Benzo-15-crown-5 ; alkali cations ; electrolytic conductance ; crown ethers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The decrease in the molar electrolytic conductance of Na+, K+, Rb+, and Cs+ tetraphenylborates, caused by the addition of benzo-15-crown-5 in acetonitrile at constant ionic strength, is analyzed according to a model involving 1:1 stoichiometry. The stability constant,K, and the limiting molar conductivity, Λ c , for each 1:1 complex are determined from the conductance measurements by using a nonlinear least squares curve fitting procedure. The stability sequence of the 1:1 complexes, as deduced from data at 288, 293, 298, 303, and 308 K, has the order Na+〉K+〉Rb+〉Cs+. Values of ΔH 0, ΔS 0, and Λ c at 298 K are reported and their significance is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00656339
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    Paper (German National Licenses)
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