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.

中文翻译：

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核壳镧系元素掺杂纳米粒子@Eu-MOF 纳米复合材料用于防伪应用

由镧系元素掺杂的纳米粒子和金属有机框架（MOFs）构建的异质纳米复合材料在治疗、催化、光学编码等方面具有广泛的应用前景。然而，MOFs的组装通常需要对纳米粒子表面进行精细的预修饰。在此，我们通过一步反应展示了铕/1,3-苯二甲酸 (1,3-BDC) MOF 在 NaYF ₄ :Ce/Tb@NaYF _{4纳米粒子上的简化生长策略。}羧酸基团通过MOFs前驱体中的油酸和1,3-BDC之间的配体交换过程接枝到纳米颗粒的表面，在反应条件下成为Eu-MOFs的生长位点。酸碱刺激反应配体N-(2-吡啶基)苯甲酰乙酰胺(HPBA)与Eu-MOF中的Eu ³⁺配位，生成NaYF ₄ :Ce/Tb@NaYF ₄ @Eu-MOF@HPBA纳米复合材料。^{Tb 3+}的发光寿命可以通过NaYF ₄惰性层来控制。暴露于NH _{3 /HAc蒸气后，以615 nm为中心的Eu} ³⁺衰减曲线有相应的变化。因此，可以有效地调节Tb ³⁺和Eu ³⁺的发光寿命。这项工作揭示了纳米粒子@MOF 混合结构的合成和时间分辨防伪应用。