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  • 1
    Electronic Resource
    Electronic Resource
    Molecular complexes of crown ethers. part 2: Complexes between crown ethers and π acceptors (1994)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 20 (1994), S. 123-129 
    Details
    ISSN: 1573-1111
    Keywords: Intermolecular charge transfer ; crown ethers ; π acceptors ; formation constant ; UV-visible spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The intermolecular charge transfer (CT) complexes of four crown ethers (CE), viz. B15C5, B18C6, DB18C6 and DB24C8 (as donors), and three acceptors, i.e. tetracyanoethylene (TCNE) 7,7,8,8-tetracyanoquinodimethane (TCNQ) and chloranil were studied in the UV-Visible region in 1,2-dichloroethane (DCE) at 298.2 K. Solid complexes were also prepared and the ratio of the donor to the acceptor was 1:1. Results indicate that the λmax of the CT band decreases whileK c (formation equilibrium constant) increases following the systematic change of the electron affinity of the π acceptors. TheK c values suggest that the phenyl group in CE plays a major role in the formation of a CT complex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00709336
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  • 2
    Electronic Resource
    Electronic Resource
    Molecular complexes of crown ethers. Part 3. Effect of cations on charge transfer complexes with TCNE (1995)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 23 (1995), S. 175-179 
    Details
    ISSN: 1573-1111
    Keywords: Crown ethers ; tetracyanoethylene ; UV-visible spectroscopy ; formation constant ; effect of cations on formation constant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The intermolecular charge transfer complexes (CT) of two crown ethers (CE), viz, B15C5 and DB18C6 (as donors), and tetracyanoethylene (TCNE), as acceptor, were studied in the UV-visible region in dichloroethane (DCE), at 298.2 K. The sequence of addition of the cation was varied in the case of B15C5 such that in one system the sequence was (CE+Cation)+TCNE and in the other (CE+TCNE)+cation. These two systems were found to be non-interchangeable, even under reflux conditions, giving differentK c values which were explained as being due to the different geometries of the CE. For the first sequence, the values most affected depended on the fit of the metal cation with the ether cavity, thus in B15C5, Na+ showed the greatest effect, while for DB18C6 it was K+.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00709575
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  • 3
    Electronic Resource
    Electronic Resource
    Molecular Complexes of Crown Ethers, Part 5: Complexes of DB18C6 with Some Acceptors (1999)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 33 (1999), S. 5-16 
    Details
    ISSN: 1573-1111
    Keywords: UV-visible spectra ; charge transfer complex ; formation constant ; DB18C6 ; TCNE ; DDQ ; halides ; electron transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The UV-Visible spectra of DB18C6 as a donor with TCNE (Tetracyanoethylene), and DDQ (2,3-dichloro-5,6-dicyano-1,4- benzoquinone) as acceptors were studied. Charge transfer spectra were obtained for these systems from which it was possible to calculate the formation constant, Kc. The effects of potassium halides were studied. This study shows that in the presence of the anion there is an electron transfer from the anion to the acceptor. This process is enhanced by the presence of the crown ether, CE. The formation of the anion salt with the acceptor, in the presence of the CE, follows the trend F = I 〉 Br 〉 Cl. It is also indicated in this study that the interaction between DB18C6 and the acceptor follow the trend DDQ 〉 TCNE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008096210619
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