Harnessing rare earth coordination chemistry for advanced photofunctional materials: from fundamental principles to emerging technologies.

Rare earth (RE) ions, characterized by unique 4f electronic configurations and shielded f-f transitions, serve as exceptional optical centers exhibiting narrow-band emission, long-lived luminescence, and rich energy-level structures. The construction of high-performance RE coordination-based photofunctional materials critically relies on the synergistic integration of the "antenna effect", provided by meticulously designed organic ligands, and the distinctive excited-state properties of RE ions. This molecular engineering approach not only maximizes the intrinsic photophysical advantages of RE elements, but also enables the precise tailoring of materials for diverse cutting-edge applications. This review provides a systematic and comprehensive analysis of RE coordination-based photofunctional materials, spanning from fundamental design principles and controllable synthesis strategies to emerging applications. We delve into the structure-activity relationships across various categories, including molecular complexes, supramolecular assemblies, coordination polymers, metal-organic frameworks (MOFs), and RE-covalent-bonded organic frameworks (RE-COFs). Furthermore, we highlight their transformative roles in optoelectronics, advanced anti-counterfeiting, biomedical imaging/therapy, radiation detection (scintillators) and photochemical catalysis. Finally, we outline current challenges and future perspectives, aiming to inspire interdisciplinary innovation and accelerate the commercialization of next-generation RE molecular photonic materials.