Responsive organic room-temperature phosphorescence materials for spatial-time-resolved anti-counterfeiting

Stimulus-responsive room-temperature phosphorescence (RTP) materials have gained significant attention for their important optoelectronic application prospects. However, the fabrication strategy and underlying mechanism of stimulus-responsive RTP materials remain less explored. Herein, we present a reliable strategy for achieving pH-responsive RTP materials by integrating poly(vinyl alcohol) (PVA) with carboxylic acid or amino group functionalized terpyridine (Tpy) derivatives. The resulting Tpy derivativesbased RTP materials displayed reversible changes in emission color, intensity, and lifetime of both prompt and delayed emission. Notably, the RTP emission undergoes a significant diminish upon exposure to acid due to the protonation of Tpy units. Taking advantage of the decent RTP emission and pH-responsiveness of these RTP films, a spatial-time-resolved anti-counterfeiting application is demonstrated as a proof-ofconcept for largely enhancing the security level. This study not only provides new prospects for developing smart RTP materials but also promotes the advancement of optical anti-counterfeiting applications. (c) 2024 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.