In order to reduce use cost and simplify detection process, it is necessary to develop multifunctional and multi-emitter Ln-MOFs luminescence sensors. The structure and property of Ln-MOFs are mainly controlled...

Heterogeneous nanocomposites constructed by lanthanide-doped nanoparticles and metal–organic frameworks (MOFs) have broad application prospects in therapy, catalysis, optical encoding, etc. However, the assembly of MOFs normally acquires delicate premodification of the surface of the nanoparticles. Herein, we demonstrate a simplified growth strategy of europium/1,3-benzenedicarboxylic acid (1,3-BDC) MOF on NaYF4:Ce/Tb@NaYF4 nanoparticles through a one-step reaction. Carboxylic acid groups are grafted on the surface of the nanoparticles via the ligand-exchange process between oleic acid and 1,3-BDC in the precursors of MOFs, which become growth sites for Eu-MOF under the reaction condition. An acid–base stimuli-responsive ligand N-(2-pyridinyl)­benzoylacetamide (HPBA) is coordinated with Eu3+ in the Eu-MOF, thereafter resulting in NaYF4:Ce/Tb@NaYF4@Eu-MOF@HPBA nanocomposites. The luminescence lifetime of Tb3+ could be controlled by the NaYF4 inert layer. After exposure to NH3/HAc vapor, the decay curve of Eu3+ centered at 615 nm has a corresponding change. Thus, the luminescence lifetime of Tb3+ and Eu3+ can be effectively tuned. This work sheds light on the synthesis of nanoparticle@MOF hybrid structures and time-resolved anticounterfeiting applications.

It is necessary for decreasing application cost of luminescent Ln-MOFs sensors to develop multiple functionalities. The ingenious design of ligands and the rational dope of Ln3+ ions are main...

The spoilage and forgery of perishable products such as food, drugs, and vaccines cause serious health hazards and economic loss every year. Developing highly efficient and convenient time−temperature indicators (TTIs) to realize quality monitoring and anticounterfeiting simultaneously is urgent but remains a challenge. To this end, a kind of colorimetric fluorescent TTI, based on CsPbBr 3 @SiO 2 nanoparticles with tunable quenching kinetics, is developed. The kinetics rate of the CsPbBr 3 -based TTIs is easily regulated by adjusting temperature, concentration of the nanoparticles, and addition of salts, stemming from the cation exchange effect, common-ion effect, and structural damage by water. Typically, when combined with europium complexes, the developed TTIs show an irreversible dynamic change in fluorescent colors from green to red upon increasing temperature and time. Furthermore, a locking encryption system with multiple logics is also realized by combining TTIs with different kinetics. The correct information only appears at specific ranges of time and temperature under UV light and is irreversibly self-erased afterward. The simple and low-cost composition and the ingenious design of kinetics-tunable fluorescence in this work stimulate more insights and inspiration toward intelligent TTIs, especially for high-security anticounterfeiting and quality monitoring, which is really conducive to ensuring food and medicine safety.