Self-Assembled Bright Luminescent Lanthanide-Organic Polyhedra for Ratiometric Temperature Sensing.

Luminescent lanthanide-containing compounds have a lot of stimulating applications. However, the fine-tuning of the optical properties of multi-nuclear lanthanide edifices is still a big challenge. We report here the coordination self-assembly of a group of bright luminescent lanthanide organic polyhedra (LOPs) with record high emission quantum yields, by using two fully-conjugated ligands featuring the triazole-pyridine-amido (tpa) chelating moiety, easily-accessible from the "Click" reaction. The self-assembled LOPs are characterized by NMR spectroscopy, high-resolution ESI-TOF-MS, and X-ray crystallography. Interestingly, inter-metal energy transfer (ET) is confirmed on the mixed-lanthanide polyhedral molecules, though the metal centers are separated nearly 2 nm apart. A feasible ratiometric luminescent thermometer, with work range from cryogenic to physiological temperatures, has been demonstrated with the mixed Eu/Tb LOPs. We envisage these molecular-level bright luminescent LOPs have great application potential in displaying, labelling/imaging, up-conversion materials etc.