A Mini-Review on the Structure–Property Relationships of Octahedral Mn 2+ Chlorido Organic–Inorganic Hybrid Complexes: A Platform for Tunable Luminescence and Multifunctionality

Pb-free organic–inorganic hybrid compounds are emerging as a versatile class of light-emitting materials, due to their optoelectronic, magneto-optic, field-sensing properties, low toxicity, and natural abundance. Particularly, ionic Mn2+ chlorido organic–inorganic hybrid compounds display high photoluminescent quantum yields, large Stokes shift, and are considered a structurally rich class of materials. A carefully selected wide variety of organic cations can be combined with [MnCl6]4– octahedra to obtain low-dimensional organic–inorganic structures such as two-dimensional (2D) sheets, one-dimensional (1D) chains, or zero-dimensional (0D) isolated octahedra, where each structure dimensionality displays unique photoluminescent properties. In this mini-review, the focus is on the structure–property relationships in ionic low-dimensional compounds containing [MnCl6]4– octahedra and a variety of organic cations. Specifically, we explore how the choice of organic cations can influence not only the characteristic red-orange emissions but also the emergent coupled functionalities, including ferroelectricity and magnetism. Conceptual connections are established to better understand the structural and property-related phenomena that govern these compounds as next-generation multifunctional materials.