Inorganic and organic anion sensing by azole family members

Anion sensing is one of the most important aspects of chemistry and interest towards anion sensing, directly or indirectly, is evident from publications of the last two decades. Anion sensing is an induced response in a receptor in terms of an optical change (color change, UV-Vis and fluorescence) or an electrochemical change due to the recognition of one or more anions. A variety of ligands, including amides, urea, crown ethers etc., have been utilized from time to time as a sensor for both cations and anions. Simple azoles as well as azoles bearing organic molecules exhibit great potential for anion sensing and have been widely used for the sensing of inorganic and organic anions. This review is focused on various azole members (imidazole, pyrazole, triazole, tetrazole and benzimidazol) and has classified them into groups for the recognition of inorganic and organic anions, and also the recognition of ions by their respective metal complexes. (C) 2020 Elsevier B.V. All rights reserved.