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  • 1
    Electronic Resource
    Electronic Resource
    Molecular design of calixarene-based ion-selective electrodes (1992)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 14 (1992), S. 285-302 
    Details
    ISSN: 1573-1111
    Keywords: Calixarenes ; ion-selective electrodes ; Na+ selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In order to obtain insights into relationships between the calix[4]arene structure and the ion selectivity in the electrode system, 20 ionophoric calix[4]arenes were synthesized and their ion selectivity (with Na+ as a standard) estimated. Among these ionophoric calix[4]arenes, 25,26,27,28-tetrakis[(ethoxycarbonyl)methoxy]-p-t-octylcalix[4]arene afforded the highest logK NA,M pot value (−3.1) in the presence of 2-fluorophenyl-2′-nitrophenylether (10) as the best of 13 plasticizers. This is the first example in which the Na+/K+ selectivity exceeds a factor of 103 in the electrode system based on the neutral carrier. The high Na+ selectivity is attributed to modification of the upper rim which ostensibly has no relation with the component of the cavity. This paper demonstrates the potential relationships between the unique structure of the calix[4]arene-based ligands and selectivity performance for the design of ion-selective electrodes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01045987
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  • 2
    Electronic Resource
    Electronic Resource
    On the selection of the optimal plasticizer for calix[n]arene-based ion-selective electrodes: Possible correlation between the ion selectivity and the ‘softness’ of the plasticizer (1994)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 17 (1994), S. 377-392 
    Details
    ISSN: 1573-1111
    Keywords: Calixarenes ; ion-selective electrodes ; plasticizer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A criterion for the selection of a suitable plasticizer for calix[n]arene-based ion-selective electrodes is discussed. The cation selectivity of plasticized membranes without the ligand was first measured as a reference. The membranes can be roughly classified into two groups. The first group shows cation selectivity in the order Cs+〈Rb+〉K+〉Na+〉Li+. The membranes in the second group are made of phosphorus plasticizers, which show a selectivity in the reverse order. The plasticizers in the first group featured a linear relationship between the dipole moment of the plasticizer (calculated by a PM3 method) and the ratio of cesium selectivity to lithium selectivity. The linear relationship supports the view that the polar membrane which includes a ‘soft’ plasticizer with a large dipole moment shows selectivity for Cs+, whereas the nonpolar membrane including the ‘soft’ plasticizer with the small dipole moment shows much lower selectivity for Cs+. Next, 2-fluorphenyl-2′-nitrophenyl ether (FPNPE) which showed the highest Cs+ selectivity and tris(2-ethylhexyl)phosphate (TEHP) which showed the highest Li+ selectivity were mixed in an appropriate ratio to make membranes with a different affinity for ‘hard’ ions. The metal selectivities of several crown-based and calixarene-based ionophores were examined in these membranes. Although a few exceptions exist, the polar ‘soft’ membrane is favorable when the interfering metal ion is ‘hard”, whereas the ‘hard’ membrane is favorable when the interfering metal ion is ‘soft’.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00707133
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    X-ray crystallographic studies of tricarbonylchromium complexes of calix[4]arene conformers: On an unusual conformation which appears in cone conformers (1994)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 19 (1994), S. 227-236 
    Details
    ISSN: 1573-1111
    Keywords: Calixarenes ; arenetricarbonylchromium ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The structures of three arene-tricarbonylchromium complexes prepared from cone and 1,3-alternate-25, 26,27,28-tetrapropoxycalix[4]arene(1) and Cr(CO)6 were determined by single crystal X-ray studies. Crystal data for 1,3-alternate-1·Cr(CO)3 are space groupP21/a,a=19.496(3)Å,b=11.118(2)Å,c=19.121(2)Å, β=109.95°(1) andV=3895Å3. The structure was refined toRw=0.068. Crystal data for cone-1·Cr(CO)3 are space groupP21/a,a=21.457(4)Å,b=12.184(1)Å,c=14.816(2)Å, β=91.61°(1) andV=3872Å3. The structure was refined toRw=0.077. Crystal data for cone-1·2Cr(CO)3 are space groupP21/a,a=18.019(3)Å,b=41.347(4)Å,c=11.743(2)Å, β=97.39°(1) andV=8676Å3. The single crystal included two similar but slightly different structures but the data were successfully refined toRw=0.092. The structure of 1,3-alternate-1·Cr(CO)3 differs only slightly from that of the regular 1,3-alternate calix[4]arene. In contrast, cone-1·Cr(CO)3 and cone-1·2Cr(CO)3 show an unusual conformation with a pair of faced gablelike roofs, which is considerbly distorted from the regular cone calix[4]arene. The origin of this distortion is discussed in combination with the spectral studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00708984
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    Paper (German National Licenses)
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