Photophysical Properties of S = 5/2 Zigzag-1D (2-Bromoethylammonium)₃MnBr₅ Antiferromagnet

It has been challenging to design multifunctional lead-free organic-inorganic hybrid halides that can exhibit fascinating magnetic and photoluminescence properties since the dimensionality of the compounds has a contrasting impact on them. In this context, our newly synthesized compound (2-bromoethylammonium)₃MnBr₅ (BEAMBr) crystallizes in the monoclinic C2/c space group with corner-sharing zigzag 1D chains of MnBr₆ distorted octahedra. Intriguingly, it exhibits a long-range antiferromagnetic ordering at low temperature (∼2.5 K) along with a typical low-dimensional broad magnetic susceptibility hump. The magnetic properties modeled by the exact diagonalization approach indicate strong intrachain and weak interchain interactions with J₁ = -50.1 K, J₂ = -13.0 K, and J' = -1.25 K, respectively, suggesting excellent one-dimensionality. In addition, BEAMBr displays orange-red emission with a photoluminescence quantum yield of 15.2%. Interestingly, electron-phonon coupling was observed in this soft distorted compound with coupling strength γ_LO = 128.3 meV, confirmed from the analysis of temperature-dependent emission line width broadening and Raman spectra.