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  • 1
    Electronic Resource
    Electronic Resource
    Multifunctional Calix[4]arenes Containing Pendant Amide and Phosphoryl Groups: Their Use as Extracting Agents and Carriers for Alkali Cations (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 27 (1997), S. 127-140 
    Details
    ISSN: 1573-1111
    Keywords: Alkali cations ; calixarene ; amide ; phosphine oxide ; complexation ; extraction ; transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The complexing, extracting and mobile carrier properties of the tetra(phosphine oxide)-calix[4]arene 1 and the hybrid diamide-di(phosphine oxide)-calix[4]arene 2 were studied. Both ligands give 1 : 1 complexes with alkali cations in THF as shown by the picrate method. 1H NMR experiments were run to follow encapsulation of sodium and potassium cations. The corresponding spectra indicate C2-symmetrical structure. The observed extraction orders of the alkali picrates were as follows K+〉Rb+〉Li+〉Cs+〉Na+ for 1 and Li+〉Na+〉K+〉Rb++ for 2. Transport kinetics was analysed by means of a model which assumes pure diffusion and which allows the evaluation of mass transfer coefficients in all systems. These coefficients and their influences on the transport rate are discussed in terms of size of the transporting species in the liquid membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007975928021
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  • 2
    Electronic Resource
    Electronic Resource
    Synergistic extractions of alkali ions byp-tert-butylcalix[4]arene and crown ether mixtures (1995)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 22 (1995), S. 107-117 
    Details
    ISSN: 1573-1111
    Keywords: p-tert-Butylcalix[4]arene ; crown ethers ; alkali ions ; liquid-liquid extraction ; synergistic effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Mixtures of macrocyclic crown ethers (L′=DC18C6, DB18C6, 18C6; L″=B15C5) andp-tert-butylcalix[4]arene (LH4) in dichloroethane exhibit synergistic effects in the extration of alkali ions (M+). These extractions are described by two independent reactions: —a two phase ion exchange: $$LH_{4org} + M_{aq}^ + \rightleftharpoons MLH_{3org} + H_{aq}^ + , (K_{ex} )$$ —the formation of an adduct in the organic phase: $$MLH_{3org} + nL_{org}^\prime (or nL_{org}^{''} ) \rightleftharpoons LH_3 ML_{norg}^\prime (or LH_3 ML_{norg}^{''} )(K_{fn} ).$$ It is shown thatn=1 for all the systems including 18 membered crown ethers (M=Na, K, Rb, Cs) and for the Na+-B15C5 system; whereasn=2 in the case of the K+-B15C5 and Rb+-B15C5 systems. Ion size effects on the stability constant of the adducts reveal strong interactions between the crown ether and the cation in the above mentioned systems. The corresponding adduct in the Cs+—B15C5 system has a very low stability constant in comparison with the others. This seems to show that B15C5 is unable to remove the Cs+ ion from the calixarene ‘cup’ in the cesium calixarenate complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00707686
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Calix[4]arenes with Pendant Amide and Phosphine Oxide Functionalities: Use as Extractive Agents and Carriers for Silver (I) Ions (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 29 (1997), S. 137-151 
    Details
    ISSN: 1573-1111
    Keywords: Calixarene ; amide ; phosphine oxide ; silver ; extraction ; transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The solvent extraction properties towards Ag+ of5,11,17,23-tetra-tert-butyl-25,27-diX-26,28-bis(diphenylphosphinoylmethoxy)calix[4]arenes (X = CH2C(O)NEt2 (1), CH2P(O)Ph2 (2), CH3 (3), CH2C(O)Et (4))have been studied. Each ligand forms a 1 : 1 complex with silver(I). Ligand1, which bears two amide functionalities, is the most efficacious,emphasizing the crucial role played by the polar amide groups. The rate oftransport of AgNO3 through a bulk liquid membrane with this ligand ascarrier was shown to be superior to that of DC18C6, a structurally-relatedmulti-oxygen donor carrier. NMR and IR data suggest that Ag+ is coordinatedto each of the oxygen atoms in the ligand leading to an encapsulatedstructure [Ag ⊂ 1]+.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007980931959
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    Paper (German National Licenses)
    Fulltext
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