Synthesis of zero-dimensional hybrid rare-earth halides for wavelength-dependent multicolor luminescence and X-ray imaging.

Zero-dimensional hybrid metal halide luminescent materials have demonstrated broad potential for applications in areas such as displays, stimulus-responsive materials, anti-counterfeiting technologies, and X-ray detection. This paper focuses on the synthesis of novel hybrid lanthanide-based halides by combining pyridinium-based ionic liquids with rare-earth luminescent centers. Two zero-dimensional hybrid lanthanide halides, (BPy)3LnCl6·H2O (BPy = 1-butylpyridinium cation, Ln3+ = Tb3+ or Eu3+), were synthesized via solution growth and grinding methods. Upon excitation by ultraviolet light, the compounds (BPy)3TbCl6·H2O and (BPy)3EuCl6·H2O emit green and red light, respectively. The photoluminescence quantum yield of (BPy)3TbCl6·H2O reached 65.7%. By adjusting the Tb3+/Eu3+ ratio and employing a method that combines melt-cooling with grinding, tunable multicolor photoluminescent samples can be rapidly prepared. Furthermore, by employing an ion-doping strategy to introduce Sb3+ into the (BPy)3TbCl6·H2O matrix, the (BPy)3TbCl6·H2O:Sb3+ sample exhibits wavelength-dependent dual-channel luminescence. The response of the zero-dimensional compound (BPy)3TbCl6·H2O to X-rays demonstrates its potential as a scintillator. The compound (BPy)3TbCl6·H2O exhibits a light yield of 28,278 photons/MeV and a detection limit as low as 106.02 nGyair/s. The spatial resolution of the scintillation film constructed using (BPy)3TbCl6·H2O and polyvinylidene fluoride reached as high as 15.1 lp mm-1. These results demonstrate the potential applications of rare-earth-based hybrid halides in anti-counterfeiting and X-ray imaging, while also providing insights for the design of novel lanthanide-based halide luminescent materials.