Tailored metal–organic tetrahedral nanocages with aggregation-induced emission for an anti-counterfeiting ink and stimulus-responsive luminescence

Abstract

Stimuli-responsive photoluminescent materials have attracted extensive research interest for applications in information security and encryption. Here, we unprecedentedly fabricated carbazole and triphenylamine-modified metal–organic tetrahedral nanocages via coordination-driven self-assembly. Interestingly, the tetrahedral cage Cage I exhibited outstanding aggregation-induced emission (AIE) performance and stimulus-responsive luminescence features, and achieved tunable photoluminescence intensity and color. Crucially, these excellent optical properties enabled the cage to act as a fluorescent ink for vapor-responsive recording and wiping information. Furthermore, we studied the emission behaviors of Cage I in the solid state under external pressure. On gradually increasing the external pressure, the luminescence of Cage I decreased initially, due to further rotation restriction, which was followed by quenching under 7.21 GPa, owing to the tight packing of the supramolecules. The subsequent release of the pressure resulted in the cage recovering the emission.