Designing Multifunctional AIEgens by Molecular Engineering of Imidazo[1,2‐a]pyridine For Color Tunable Molecular Salts, Anti‐Counterfeit Applications and Sensing of Mn²⁺, Ag⁺, and Fe³⁺

Mechanochromic materials, known for their ability to change color in response to mechanical stimuli such as pressure, stretching, grinding, or rubbing, hold significant importance due to their diverse applications. In this study, we synthesized and characterized two novel pyridine-tethered imidazo[1,2-a]pyridine mechanoresponsive luminogens with appended tetraphenylethene, named GBY-10 and GBY-11. GBY-10 exhibited reversible mechanofluorochromism, while GBY-11 did not revert to its original color after solvent fuming. The photophysical properties of these luminogens were significantly influenced by the position of the terminal pyridine. Additionally, we created color-tunable mechanoresponsive molecular salts by co-grinding GBY-11 with various aryl acid derivatives. Co-grinding GBY-11 with pentafluorobenzoic acid resulted in a significant bathochromic shift of the emission maxima by 66 nm, compared to 37 nm and 12 nm shift for benzoic acid and para-nitrobenzoic acid, respectively. This counter-ion-dependent luminescence suggests strong electronic interactions between the counter ions. These luminogens also demonstrated reversible pH-responsive behaviour, making them suitable for anti-counterfeiting applications. Furthermore, the pyridine-functionalized luminogen, GBY-10, showed metal ion detection (Mn²⁺, Ag⁺, Fe³⁺) ability in water, with detection limits as low as 0.0043, 0.015, and 0.0029 mM, respectively. This report opens new avenues for designing promising AIE-active materials for potential applications in anti-counterfeiting, sensing, optoelectronics, and biomedicine. A de-novo approach of engineering imidazo[1,2-a]pyridine scaffold to mechanoresponsive AIE-active molecules for anti-counterfeiting and metal sensing applications. By co-grinding the designed luminogens with various aryl acid derivatives, color tuneable mechanoresponsive molecular salts can be further developed.