Construction and Emission Tuning of the One-Dimensional (MBI)CdCl <b> ₄ </b> ·H <b> ₂ </b> O toward Anti-Counterfeiting and Information Encryption

Organic-inorganic hybrid metal halides (OIHMHs) have attracted considerable attention because of their superior optoelectronic properties and structural versatility, yet one-dimensional (1D) OIHMHs remain the least studied relative to their 0D, 2D, and 3D counterparts. Here, a new 1D blue-emitting hybrid cadmium chloride phosphor, (MBI)CdCl4·H2O, was constructed using 2-methylbenzimidazole (MBI) as the organic ligand. It crystallizes in the monoclinic P21/c space group, consisting of distorted [CdCl6]4– octahedra connected via edge sharing. Incorporation of Sb3+ ions with stereochemically active 5s2 lone-pair electrons yields (MBI)Cd0.7Sb0.2Cl4·H2O, which exhibits highly efficient yellow emission with a photoluminescence quantum yield (PLQY) of 92.0%. In addition, doping with high-spin Mn2+ ions produces photoluminescent (MBI)Cd0.85Mn0.15Cl4·H2O crystals with a PLQY of 16.7%. Leveraging the tunable luminescence of this Cd halide, these materials were further demonstrated in anticounterfeiting and information encryption applications, highlighting a promising avenue for the development of functional metal halides.