Balamurugan Tharmalingam
In recent decades, smartphone-based analytical methods have gained increasing attention, mainly due to their widespread user-friendliness, enhanced computational capabilities, cost-effectiveness, and the ability to simultaneously acquire and process data. Accurate ion detection plays a vital role in environmental monitoring, industrial methods, and human health. Schiff base molecules and their coordination compounds have attracted significant attention as versatile ion-sensing probes owing to their ease of synthesis and structural tunability. Recently, the integration of Schiff base chemosensors through smartphone platforms has enabled cost-effective, portable, and user-friendly sensing systems for the detection of trace-level metal ions in environmental and biological samples. This review summarizes recent advances in smartphone-based small-molecule chemosensors for the recognition of various anions and cations, including Th4+, Zn2+, Cu2+, Ag+, Hg2+, Al3+, CN-, F-, and EDTA. Particular emphasis is placed on sensing mechanisms, recognition methods, analytical strategies, and their applications in real-sample analysis. These developments highlight the growing potential of smartphone-integrated Schiff base sensors as practical tools for point-of-care testing and on-site environmental monitoring.