Ionophoric ideality for the extraction of small metal cations
by means of aza-macrocycles and 9-crown-3, 10-crown-3,
11-crown-3, or 12-crown-3 crown ethers
Triaza macrocyles ionophorically bound to small cations (Illustration by Lindy Arrowood,
Scientific Illustrator ONU-6207 Kankakee, IL 60901)
a169 1/2 South Schuyler Avenue, Kankakee, Illinois 60901, USA bOlivet Nazarene University, Department of Chemistry, PO Box 592, Kankakee, IL 60901-0592, USA
Abstract
The cavities of smaller crown ethers and azacylces have the
ionophoric ability to bind to small metal cations. The most
effective ring structure is difficult to determine due to non-
correlative publications. The crown ether may be more efficient
when containing one or two nitrogen heteroatoms. However,
azacylces such as Cyclen may have a higher susceptibility to cationic extraction
than the ethers. The addition of ligating amino side-arms is another
factor that may increase extractive competence. Once ideally
customized through organometallic chemical engineering, the
structure could be serviceable in the commercial collection of
metals from mineral springs or ocean water, as well as a purifying
agent for waste water.
A Tolkienian Dilemma
Which Ring?
Various publications have studied various rings and determined several
to be highly effective ionophores. But those that test small crown ethers
ignore the azacycles. Others that include sidearm possibilities don't
investigate the smaller ring radii. Of course, this is all dependent on
which metal is being extracted.
Side arm possibilities
Although the azacycles appear most viable, study of the smaller
ethers and side arm manipulation are worthy of investigation.
