Radical Photochromism-Induced Phosphorescence Enhancement for Dynamic Anticounterfeiting

Stimuli-responsive materials that synergistically combine dynamic photochromism and tunable room-temperature phosphorescence (RTP) are highly promising for advanced optical applications. However, achieving photochromism-promoted RTP emissions remains a significant challenge. Herein, we present a facile strategy to construct such smart materials by supramolecular assembly of poly(acrylic acid) (PAA) with halogenated (I, Br, and Cl) terpyridine derivatives (X-TPY). The resulting composite materials (X-TPY@PAA) exhibit enhanced RTP with tunable afterglow duration from 1.0 to 5.0 s, along with photochromic behavior through radical generation/interaction. Interestingly, this photochromic reaction does not lead to the commonly observed quenching effect; instead, it unusually enhances the afterglow duration of room-temperature phosphorescence (RTP). On the basis of these dual functionalities, we demonstrate a multilevel information encryption system with both temporal and spatial resolution. This work provides a reliable design strategy that utilizes radical photochromism to achieve controllable phosphorescence enhancement for dynamic anticounterfeiting.