Organic Linkers Enable Tunable Transfer of Migrated Energy from Upconversion Nanoparticles.

Energy transfer plays a pivotal role in applying lanthanide-doped upconversion nanoparticles (UCNPs) as optical probes for diverse applications, particularly in biology and medicine. However, achieving tunable energy transfer from UCNPs to different acceptors remains a daunting challenge. Here, we demonstrate that using small organic molecules as linkers, the energy transfer from UCNPs to acceptors can be modulated. Specifically, organic linkers can enable efficient energy transfer from NaGdF4:Yb/Tm@NaGdF4 core-shell UCNPs to different acceptors. Moreover, the organic linker-mediated energy transfer can be facilely tuned by simply changing organic linkers. Based on our mechanistic investigations, the extraction of Gd3+ migrated energy from UCNPs by organic linkers and the subsequent energy injection from linkers to acceptors should be the two key processes for controlling the energy transfer. The tunable energy transfer from UCNPs allows us to design novel applications, including sensors and optical waveguides, based on UCNPs. These findings may open up new ways to develop UCNP-based bioapplications and advance further fabrication of hybrid upconversion nanomaterials.