Highly Efficient and Uncommon Photoluminescence Behavior Combined with Multiple Dielectric Response in Manganese(II) Based Hybrid Phase Transition Compounds

A series of multifunctional photoluminescent materials, [pyrrolidinium](2)MnBr4 (1), [N-methylpyrrolidinium](2)MnBr4 (2), and [N-methylpyrrolidinium]MnBr3 (3), were obtained by means of regulating diverse organic cations and different coordination modes of inorganic metal ions. Interestingly, compounds 1, 2, and 3 exhibit different dielectric switching and relaxation behavior in the process of structural transformations. Furthermore, compounds 1, 2, and 3 possess intriguing photoluminescence properties. When subjected to UV light, tetrahedrally coordinated compound 1 shows extraordinarily strong green light emission with a high quantum yield of 51.41 %. By changing the organic cation, compound 2 exhibits an unusual orange emission under ultraviolet excitation, which is different from that of conventional tetrahedrally coordinated manganese-based compounds. By the regulation of coordination modes of inorganic metal ions, octahedrally coordinated compound 3 emits bright red light with a high quantum yield of 36.76 %. This finding may open a new approach toward designing multifunctional photoluminescent materials.