Chromogenic and Fluorogenic Schiff Bases for Toxic Analyte Detection: A Review on ESIPT-Based Recognition.

Schiff base probes have emerged as highly effective chromogenic and fluorogenic sensors for the selective detection of toxic cations and anions. Among various sensing mechanisms, Excited-State Intramolecular Proton Transfer (ESIPT) has gained significant attention due to its rapid response, high sensitivity, and tunable optical properties. This review highlights recent advancements in ESIPT-based Schiff base probes for toxic analyte recognition, emphasizing their structural design, sensing mechanisms, and practical applications. The interplay between Schiff base frameworks and ESIPT dynamics enhances signal transduction, enabling the visual and fluorescence-based detection of toxic analytes and other environmental pollutants. The review also explores emerging trends in receptor development, including multi-analyte detection, real-time monitoring, and bioimaging applications. A comparative analysis of various Schiff base sensors highlights their selectivity, detection limits, and practical usability in environmental and biological systems. This comprehensive overview aims to provide insights into the future design of ESIPT-driven Schiff base receptors for enhanced toxic analyte detection and environmental monitoring.