Innovative Optical Chemosensors for Ions and Small Molecules

The development of chemosensors for recognition of chemically and environmentally important species, along with environmental hazards, has been an attractive area of research. Due to its remarkable features, such as high sensitivity, selectivity, rapid response, naked‐eye detection, and broad applicability, supramolecular chemistry has been widely explored in this context. Exploring novel signaling mechanisms involving interactions between the signaling group and the analyte is of current interest. Recently, many studies have been reported on optical sensing strategies for various environmentally and biologically important analytes as well as toxic species. Optical sensing approaches are considered to be low‐cost, non‐invasive, and environmentally friendly, and can be carried out under mild reaction conditions. This review article provides a comprehensive overview of the recent developments in the field of optical chemosensors, and their design strategies, along with various signaling mechanisms, like photoinduced electron transfer (PET), internal charge transfer (ICT), Förster resonance energy transfer (FRET), excited state intramolecular proton transfer (ESIPT), excimer/exciplex formation, etc., that have emerged in the past few years. Finally, the challenges and future aspects of optical sensors have been presented.