Biomimetic Macrocyclic Receptors for Carboxylate Anion Recognition

Carboxylate anions are ubiquitous in nature and are involved in several biological processes. For example, the carboxylate group of the D-alanyl-D-alanine terminal part of the cell wall peptidoglycan is selectively recognized by the binding pocket of vancomycin-type antibiotics,[1] di- and tricarboxylates are involved in several metabolic processes,[2] and other carboxylate anions are known to be substrates or inhibitors of enzymes.[3] Moreover, chiral propionic acid derivatives are widely used in therapy as nonsteroidal anti-inflammatory drugs[4] and carboxylate polyanions can form well-ordered self-assembled structures when mixed with complementary polycations or hydrogen bonding donor groups.[5] For all these reasons the synthesis of biomimetic receptors for carboxylate anions have been recently pursued in supramolecular chemistry,[6–8] with the aim of obtaining 1) useful models of the biological processes, 2) biologically active molecules, 3) selective chemosensors, and 4) selective separation systems. The objective of this article is to highlight the most successful approaches followed in the design and synthesis of biomimetic receptors for carboxylate anion recognition, with major emphasis on the results achieved in the last 5 years with macrocyclic compounds, and on our own work.