Brightness and AIEE behaviour of methylenebis(4,1-phenylene) linkage electron donor–acceptor-based dyads and their implications for robust quantification of explosive picric acid in both aqueous medium and solid state†

Organic luminescent materials having photoluminescence in their solid state have become emerging trends in chemistry, materials science, and biology due to their versatile potential applications. In the present contribution, we have introduced some methylenebis(4,1-phenylene) electron donor–acceptor-based fashionable solid-state fluorescent molecules, MBA, MBB, and MBH, having exciting photoluminescence characteristics in their solid and aggregate states. Interestingly, all probes exhibited a compelling aggregation-induced enhanced emission (AIEE) phenomenon in aqueous media. The mechanistic aspects of solid-state brightness and AIEE behavior are elucidated by diverse spectroscopic, microscopic, and X-ray crystallographic analyses. Employing their intriguing AIEE characteristics, the water-suspended low dimensional particles have been employed as a sensor, demonstrating rapid sensitivity and brilliant selectivity towards the nitro-explosive compound picric acid (PA). The estimated limits of detection (LOD) and quantification (LOQ) reach as low as the μM to nM range in the aqueous medium. The fluorescent paper strip-based test kit experiment has been demonstrated for instant detection of PA through visual examination in the solid state, rendering the protocol quick, cost-effective, and appropriate for on-spot solid-state recognition.