Molecular Design‐Enabled Pyridinium‐Based Metal Halide Glass Scintillators with Robust Glass‐Forming Ability and Tailorable Radioluminescence

Abstract Organic–inorganic hybrid metal halide (OIMH) glasses represent a promising class of functional materials due to their facile synthesis, high transparency, and composition tunability. However, a significant gap persists in the diversity of applicable glassy material systems and the availability of well‐defined structural design guidelines compared to their crystalline counterparts. Herein, we synthesized a series of pyridine‐based OIMH crystals exhibiting efficient luminescence and exceptional melting properties. Through systematic benzyl functionalization and phenyl substitution on the pyridinium cation, we have optimized both luminescence efficiency and glass‐forming ability (GFA). Among them, (1‐Bz‐3‐PhPy) 2 MnBr 4 (1‐Bz‐3‐PhPy = 1‐benzyl‐3‐phenylpyridinium) displays the lowest melting temperature ( T m = 111.9 °C) and the highest glass transition temperature ( T g = 50.3 °C), yielding excellent GFA as indicated by a high T g / T m ratio of 0.84. The exceptional GFA is further demonstrated by the glass's remarkable stability, retaining an amorphous state even after annealing at 80 °C for 8 weeks. It also allows for co‐melting with other easily crystallizable components, which facilitates the preparation of two‐component glasses with precisely tunable radioluminescence properties. These advanced glassy materials provide opportunities for practical X‐ray imaging and real‐time visualization of multicolor radiation detection, further establishing new design paradigms for OIMH scintillators.