A review of the applications of Schiff bases as optical chemical sensors

Schiff bases and their metal complexes have become well-known for catalytic (e.g., in various synthetic processes) and biological properties (e.g., antifungal, antibacterial, anti-malarial, and antiviral characteristics) since their discovery by Hugo Schiff in 1864. As synthetic compounds, they are employed as versatile tools in numerous applications such as fluorescent turn-on/turn-off sensors for the determination of diverse analytes (e.g., metallic components). As such, they can offer a way to identify toxic ions and/or to provide their speciation in environmental media. This review covers a broad range of Schiff bases that are used in sensing applications for metallic cations and anions in various kinds of environmental and biological media. (C) 2019 Elsevier B.V. All rights reserved.