Structure and Photoluminescence Transformation in Hybrid Manganese(II) Chlorides

Hybrid metal halides with tunable photoluminescence (PL) properties have emerged as a novel light-emitting material. Hybrid manganese halides are especially attractive due to the eco-friendly and highly emissive advantages. However, the PL tunability induced by structural modulation in manganese halides has rarely been investigated. Herein, a new one-dimensional (1D) hybrid manganese chloride, (4AMP)₄ClMn₃Cl₁₃·HCl (4AMP = 4-(aminomethyl)pyridinium), where the corner-sharing octahedral manganese chloride chains of [Mn₃Cl₁₃^7-]_∞ are surrounded by organic cations, has been prepared. The addition of Zn²⁺ ions into precursor solution results in the formation of zero-dimensional (0D) single crystals of (4AMP)Zn_1-MnCl₄·H₂O (x = 0-1) with isolated [Zn_1-MnCl₄^2-] tetrahedral geometry. This structural transformation leads to the PL conversion from red to green emission with an increase of photoluminescence quantum yield (PLQY) from 4.9% to 12.7%. Moreover, the incorporation of other transition metal ions (e.g., Zn²⁺, Co²⁺, and Cu²⁺) reveals the concentration-dependent structure modulation, where the 1D to 0D structure transformations are achieved upon the introduction of these transition metal ions at high concentrations. This work provides a new strategy to modulate the structure and luminescence in manganese halides with tunable PL properties, which could be expanded to other hybrid metal halides.