TAEK DONG CHUNG
Institute of Medical and
Biological Engineering, Medical Research Center,
Seoul National University, Yongon-dong 28, Chongro-ku,
Seoul 110-744, Korea.
and
HASUCK KIM
Department of Chemistry and Center for Molecular Catalysis,
Seoul National UniversityShilim-dong san56-1, Kwanak-ku,
Seoul 151-742, Korea.
Abstract
Electrochemistry of calixarene as a redox-dependent ionophores
and its structural dependence are described. One or more redox-centers
such as quinone, ferrocene, cobaltocenium and ruthenium bipyridine
moieties have been introduced into the calixarene frame of the lower
or upper rim. Although the electrochemical behavior depends mainly on
the inherent redox property of these electrochemically active groups,
the structural effect and solvent also play important roles,
especially, in the presence of charged guests. When cationic
species such as metal ions and ammonium ion are added to
a quinone-functionalized calixarene solution, electron transfer
to quinone is enhanced by the electrostatic effect or the formation
of hydrogen bonds. In addition to redox-active hosts for voltammetric
use, a number of calixarenes with novel structures have been developed
as ionophores for potentiometric analysis and found to be successful
for some target ions. In terms of Na+, Cs+ and Ca2+ selective
ionophores for ion-selective electrodes, calixarenes are found
to be excellent compared to crown ether derivatives or cryptands.
Calixarenes can be also utilized to construct chemically modified
electrodes, which are sensitive to gas species and biologically
important compounds. The sophisticated design and synthesis of
calixarenes are essential to specific potential applications to
diverse fields.
Key words: calixarene, redox-dependent ionophore,
electrochemistry,
sensory device.