Pressure‐Induced Controllable Multicolor Emission in Ethyl 7‐hydroxy‐2‐oxo‐2H‐chromene‐3‐carboxylate

Organic piezochromic materials represent an important class of stimulus-responsive materials with broad prospects for pressure-sensing applications. The achievement of high sensitivity and a large color contrast under external stimulation is key to broadening their practical applications. In this work, the piezochromic behavior and phase transition of ethyl 7-hydroxy-2-oxo-2H-chromene-3-carboxylate (EHC) were reported. At 1.0 GPa, EHC undergoes a pressure-induced phase transition, and as the pressure increases, it exhibits controllable multicolor emission shifting from blue to green and then to yellow. Below 1.0 GPa, EHC exhibited a sensitivity of 1.12 nm·GPa⁻1 and a color contrast of 1 nm. After the phase transition, these values were significantly increased to 11.63 nm·GPa⁻¹ and 186 nm, respectively, demonstrating its potential as an excellent colorimetric sensor for external pressure. This enhancement may be attributed to strong intermolecular interactions formed at higher pressures. In summary, this work provides valuable insights into the relationship between molecular optical properties and structure, and also facilitates the development of new piezochromic luminescent materials.