Host-guest strategy for full-visible-spectrum piezochromism in halogen-bonded organic frameworks

Full-visible-spectrum piezochromism is vital for advanced anti-counterfeiting and storage device applications, yet remains challenging. Polycyclic aromatic hydrocarbons represent a promising class of piezochromic materials. However, pressure-induced structural disorder severely limits their performance by causing photoluminescence (PL) quenching through energy dissipation. In framework materials, host-guest modes offer a promising avenue to overcome the limitations. Herein, we demonstrate that the halogen-bonded organic framework host incorporating acridine guests (denoted as XOF@AD) enables full-visible-spectrum piezochromism modulation with the PL red-shift of 237 nm during compression. Both experiments and calculations reveal that strengthened π–hole···π interactions lower its interaction energy to preserve the structural rigidity of XOF host. This suppresses the structural disorder of AD guests and maintains their enhanced π–π stacking interactions, which leads to a decreased band gap. This work establishes host-guest 3D-XOF as a superior platform that achieves full-visible-spectrum piezochromism and presents promising potential for pressure-responsive sensing. The performance of piezochromic framework materials is often limited by pressure induced structural disorder causing photoluminescence quenching through energy dissipation. Here, the authors show host-guests halogen-bonded organic frameworks that enable full visible-spectrum piezochromism modulation with a photoluminescence red-shift during compression.