Regulation of the switch between X-ray scintillators and photo/sonocatalysis generation of reactive oxygen species in lanthanide-titanium clusters via energy transfer pathways

A class of orthogonal multifunctional lanthanide-titanium clusters, Ln₄Ti₉, was obtained by reacting 4-trifluoromethylbenzoic acid, isopropyl titanate, and Ln(OAc)₃·xH₂O under solvothermal conditions. These clusters can be used for the purification of colored dye wastewater and for high-performance X-ray scintillators. Specifically, the metal centers in the cluster nucleus of Ln₄Ti₉ are arranged in a near-planar manner, and the ligands are tightly wrapped around the cluster nucleus, which ensures the stability of the cluster in solution. In-depth exploration of the energy transfer pathways has demonstrated that the Eu₄Ti₉ structure possesses an efficient antenna effect and optimal energy level matching, exhibiting a bright red luminescence. Furthermore, Eu₄Ti₉ exhibits excellent X-ray scintillator performance, with a light yield of up to 11,677 photons∙MeV^-1 and a detection limit as low as 2.2 μGy∙s^-1, which is 2.5 times lower than the clinical standard for medical use (5.5 µGy∙s^-1). It also shows excellent radiation stability after 36 radiation cycles and enables low-dose X-ray imaging. Under white light irradiation of 60 mW·cm^-2, the rapidly generated ROS storm of Gd₄Ti₉ almost completely degraded methylene blue (MB), rhodamine B (RhB), and norfloxacin (NFX) in aqueous solution within 50 and 40 min, respectively, with degradation rates as high as 0.0216 min^-1, 0.0592 min^-1, and 0.0146 min^-1, respectively. This work applies a highly stable lanthanide-titanium cluster system in aqueous solution to the field of photocatalytic wastewater purification, specifically targeting colored dyes and antibiotics.