From elementary to advanced: rational design of single component phosphorescence organogels for anti-counterfeiting applications†

Abstract

Pure organic luminescent materials that exhibit reversible room-temperature phosphorescence (RTP) under external stimuli are receiving significant attention for their potential applications in dynamic anti-counterfeiting. This study outlines in detail the design, synthesis and stimuli-responsive properties of two pure single-component organic RTP molecules (DBF-dAc and DBF-dPh) with rigid chemical structures. Molecular dynamics simulations indicated that these molecules might serve as efficient low-molecular-weight organogelators. The presence of multiple carbonyl groups and aromatic rings in the DBF-dAc and DBF-dPh structures likely promoted intersystem crossing, imparting them phosphorescent properties in the rigid gel state. The experimental results confirmed that DBF-dAc and DBF-dPh were capable of forming stable gels in a mixture of DMSO/H₂O, facilitated by balanced intermolecular π–π interactions. In the gel state, both DBF-dAc and DBF-dPh formed nanoneedle structures of approximately 100 μm in length. Remarkably, the DBF-dPh gel demonstrated exceptionally long-lived room-temperature phosphorescence (lifetime of 35.2 ms). In addition, the DBF-dPh gel possessed multi-level anti-counterfeiting capabilities responsive to phosphorescence lifetime, UV light, and thermal stimuli. The successful development of the single-component phosphorescent DBF-dPh gel provides crucial insights and guidance for future initiatives, including the theoretical screening of organogelators and the design of multi-level stimuli-responsive RTP materials for dynamic anti-counterfeiting.