Gaw. Derwish et al., MOLECULAR-COMPLEXES OF CROWN-ETHERS .2. COMPLEXES BETWEEN CROWN-ETHERS AND PI-ACCEPTORS, Journal of inclusion phenomena and molecular recognition in chemistry, 20(2), 1994, pp. 123-129
The intermolecular charge transfer (CT) complexes of four crown ethers
(CE), viz. B15C5, B18C6, DB18C6 and DB24C8 (as donors), and three acc
epters, i.e. tetracyanoethylene (TCNE) 7,7,8,8-tetracyanoquinodimethan
e (TCNQ) and chloranil were studied in the UV-Visible region in 1,2-di
chloroethane (DCE) at 298.2 K. Solid complexes were also prepared and
the ratio of the donor to the acceptor was 1 : 1. Results indicate tha
t the lambda(max) of the CT band decreases while K-c (formation equili
brium constant) increases following the systematic change of the elect
ron affinity of the pi accepters. The K-c values suggest that the phen
yl group in CE plays a major role in the formation of a CT complex.