SCAN: Recognition of anionic substrates by artificial polyammonium receptors

The recognition of anionic substrates is an active research area of supramolecular chemistry, due to the important role of anions in biological, clinical, industrial and environmental fields. Carboxylate anions, for example, are used in diverse industries such as plastic, pharmaceutical and food. In addition carboxylate groups are also present in many pesticides and are the active groups in many biological processes. The recognition process of carboxylate anions in water is governed by multiple factors, acting in a cooperative fashion, not all completely understood. Different kind of receptors has been used, among them protonated polyazamacrocyles. These receptors offer the possibility of recognition of carboxylates via strong ion-ion electrostatic interactions assisted by multiple hydrogen bonding formation. In spite of this, even in cases where the shape and size between the partners seem to match well, the corresponding binding constants are not very high. Effects such as the type of the receptor counterion and possible repulsions between parts of the partners play an important role.

Trying to contribute to the clarification of the recognition process of anions, we have studied by various techniques the binding ability of anions with different artificial receptors and an overview of the main conclusions will be presented.

Abstract