ABSTRACT
Anion recognition, binding and transport is an emerging field of supramolecular chemistry reflecting its relevance to biochemical systems, recycling and environmental processes, catalysis and medicine. Recent advances in the field of anion coordination chemistry have made available a wide range of synthetic supramolecular anion receptors with a variety of interesting binding and structural motifs that occur both in solution and in the solid state. A considerable number of these compounds has now been proved in liquid-liquid extraction and membrane transport systems. It is the intention of this section to give an overview of the principles of supramolecular anion extraction. Furthermore some of the results of such studies were summarized in order to illustrate the characteristic extraction properties of the receptors as well as to show their potential for developing new anion separation processes for use in industrial, environmental and analytical applications. The receptor types discussed include tripodal, macrocyclic and macrobicyclic polyammonium compounds, guanidinium salts, calixarenes, steroid-based and hetero-ditopic receptors and dual-host systems.
