Scintillators are materials that convert high-energy particles or radiation into low-energy photons, playing a crucial role in imaging applications across healthcare, security, and industrial non-destructive testing. However, commercial inorganic scintillators face several challenges, including low radiation stability, complex preparation processes, and poor processability.

Metal-organic frameworks (MOFs) are emerging as promising alternatives for new scintillators due to their strong structural designability, straightforward preparation, and excellent luminescent properties. Existing research indicates that modulating open metal sites can effectively enhance the gas adsorption, catalysis, and chemical sensing performance of MOFs. However, the potential for improving photoluminescence and X-ray excited luminescence through this method remains largely unexplored, which limits the practical application of MOFs in X-ray detection and imaging.

To address this gap, a research team from the Xinjiang Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences has synthesized Zr-ADIP nanocrystals that feature eight intrinsic open metal sites per Zr cluster by incorporating a ligand containing isophthalic acid units.

The researchers proposed a strategy that utilizes modulators to occupy these open metal sites, thereby modulating the electronic levels of the MOF material and significantly enhancing its luminescence efficiency. The study found that the Zr-ADIP-BzOH compound, which has benzoic acid occupying the metal sites, displayed exceptional X-ray detection performance, with a detection limit as low as 0.53 μGy s⁻¹—ten times lower than the minimum dose rate required for medical X-ray imaging.

Additionally, by leveraging the excellent X-ray excited luminescence of the synthesized MOFs, the team constructed an organic polymer composite scintillator film device. This device was used to perform a series of rotational angle imaging on a clam sample, enabling non-destructive detection of its internal structure and the morphology of the contained pearls.

This study introduced a strategy for incorporating intrinsic open sites and modifying them with modulators to enhance the luminescence of MOFs. This approach presents a new pathway for the structural design and performance enhancement of innovative scintillators.

The findings were published in ACS Applied Nano Materials and received financial support from the National Key Research and Development Program of China and the National Natural Science Foundation of China.

Schematic representation of luminescence enhancement of MOFs based on ligand modulation and modulator modification strategy (Image by the Xinjiang Key Laboratory of Trace Chemical Substances Sensing)