Mixed‐Dimensional Diammonium Manganese(II) Bromide Hybrid Incorporating 1D Chains and 0D Tetrahedra

Mixed‐dimensional (MD) organic–metal halide hybrids (OMHHs) provide an emerging platform for integrating distinct structure‐dependent optical and magnetic behaviors within a single crystalline phase. While the photophysical properties of conventional low‐dimensional (LD) OMHHs have been widely studied, organic–inorganic hybrids that combine multiple molecular‐level dimensionalities remain largely underexplored. Here, we report a structurally unique MD diammonium manganese(II) bromide hybrid, (TMPDA) 3 (Mn 2 Br 6 )(MnBr 4 ) 2 (TMPDA = N,N,N′,N′‐tetramethyl‐1,3‐propanediammonium), which simultaneously incorporates one‐dimensional (1D) [Mn 2 Br 6 2− ] ∞ chains and zero‐dimensional (0D) MnBr 4 2− tetrahedra within a single crystalline framework. This architecture enables two optical centers to coexist in the same material, yielding excitation‐dependent dual emissions from both the 1D chains and 0D tetrahedra with high photoluminescence quantum efficiencies (PLQEs) of up to 62%. Magnetic measurements reveal weak antiferromagnetic interactions along the 1D chains, arising from Mn···Mn superexchange mediated by bridging bromides. These findings highlight the opportunities offered by MD OMHHs to expand structural and functional tunability beyond traditional LD hybrids, opening new directions for designing multifunctional materials with coupled optical and magnetic properties.