Synthesis of transition metal-sensitized lanthanide near-infrared luminescent nanoparticles

The versatility of lanthanide-doped near-infrared (NIR, 700-1,700 nm) luminescent nanoparticles makes them valuable tools in various scientific and technological fields, from bioimaging to information security. However, the luminescence intensity of typical lanthanide-doped nanoparticles is significantly influenced by the efficiency of the sensitizer. The introduction of transition metal ions (such as Cr³⁺, Mn²⁺ and Ni²⁺) can greatly enrich the library of lanthanide NIR luminescence nanoparticles. We have reported a new crystalline nanoparticle, Na₃CrF₆, for high-brightness NIR emission from lanthanide activators (such as Er³⁺, Tm³⁺, Yb³⁺ or Nd³⁺). As an emerging luminescent material, a straightforward and scalable synthesis approach for these nanostructures holds promise for their broader application. Here we have refined and standardized the steps for transition metal-sensitized lanthanide luminescent nanoparticles, thereby establishing a library of advanced luminescent materials for researchers engaged in luminescent materials. The Protocol enables the precise preparation of chromium-, manganese- and nickel-trifluoroacetate, the synthesis of three types of transition metal-sensitized lanthanide nanoparticle and the fabrication of chromium-sensitized lanthanide homogeneous and heterogeneous nanostructure. Moreover, we provide verification protocols for each step's output and guidelines for adjusting synthesis conditions. To aid in the reproducible synthesis of these nanoparticles, we also include a troubleshooting guide of the various stages. The estimated duration for synthesizing transition metal trifluoroacetate, transition metal-sensitized lanthanide nanoparticles and core-shell transition metal-sensitized lanthanide nanoparticles are ~70, 30 and 30 h, respectively. These procedures can be carried out by users with expertise in chemistry or materials science.