Credit: @Science China Press
Metallacages prepared via coordination-driven self-assembly have received extensive attention because of their three-dimensional layout and cavity-cored nature. The construction of light-emitting materials employing metallacages as a platform has also gained significant interest due to their good modularity in photophysical properties, which bring emerging applications in fields as diverse as sensing, biomedicine, and catalysis.
However, the luminescence efficiency of conventional luminophores significantly decreases in the aggregate state because they encounter unfavorable aggregation-caused quenching (ACQ). Therefore, it was quite a challenge to fabricate light-emitting metallacages with high luminescence efficiency in various physical states.
In 2001, Tang's group discovered aggregation-induced emission (AIE) phenomenon that some nonluminous or weakly emissive materials in molecular state are highly emissive in aggregate state. The underlying mechanism accounting for the AIE effect was disclosed as restriction of intramolecular movements. So far, AIE has been a promising research field for more than 20 years, and brings a new opportunity to construct light-emitting metallacages with high luminescence efficiency.