Solubility‐Driven Rapid and Large‐Scale Synthesis of Solvatochromic Luminescent Organic–Inorganic Manganese(II)‐Based Halides for Advanced Anti‐Counterfeiting

Abstract Solvatochromic luminescent materials that can change their luminescence color upon solvent treatment have attracted considerable attention owing to their frontier applications in sensing and information encryption technologies. However, existing solvatochromic luminescent materials typically suffer from a slow response rate, limited color tunability, insufficient luminescence efficiency, and complicated synthesis process. Herein, a facile solvent‐assisted and solubility‐driven powder‐to‐powder strategy is developed for quick and mass synthesis of solvatochromic luminescent organic–inorganic manganese(II)‐based halide microcrystals. The as‐synthesized 0D green‐emissive (TMA) 2 MnCl 4 (TMA: tetramethylammonium) and 1D red‐emissive (TMA)MnCl 3 microcrystals can be reversibly converted into each other upon contact with different solvents. The solvent‐induced phase transformations are accompanied by the strip of TMACl or MnCl 2 components, leading to the change of the coordination number of Mn 2+ and therefore the crystal field strength. Correspondingly, the emission color realizes a reversible switching between green and red. Notably, the phase transformation exhibits high selectivity toward solvents, and a fast response time in just 0.9 s from (TMA) 2 MnCl 4 to (TMA)MnCl 3 . The advances in these solvatochromic luminescent materials provide exciting opportunities for constructing a series of multicolor anti‐counterfeiting and information encryption patterns. This work provides new insights for solvatochromic material design and promotes advanced encryption development.