Mechanochromic and AIE active fluorescent probes for solution and vapor phase detection of picric acid: Application of logic gate

Development of organic probes through simple synthetic methodology with exceptional fluorescence properties in aqueous media, strong resistance to photobleaching, and diverse applications in solutions and vapor phase sensing are inevitably pivotal. Herein, fluorene based aggregation induced emission (AIE) active probes SM1 and SM2 were developed through a single-step Knoevenagel condensation reaction. Probes exhibited distinguished solvatochromism and reversible mechanochromism. AIE active probes SM1 and SM2 were further applied for the rapid solution-phase detection of picric acid (PA) through excellent fluorescence quenching with LOD down to 2.09 and 3.65 nM, respectively, where PET and FRET featured as vital sensing mechanisms. The sensing mechanism was supported through density functional theory (DFT) and dynamic light scattering (DLS) analyses. Probes also demonstrated the quick naked-eye colorimetric detection of PA. Dip coated fluorescent films were conveniently constructed for the efficient vapor phase and paper based detection of PA. Besides, AIE active probes were effectively employed for the quantitative recognition of PA in river and lake water samples. An INHIBIT logic device was also fabricated via the UV–visible response of probes for PA.