Synthesis, structure and red-light emission of a manganese halide directed by a methyldiphenylphosphine oxide complex

Controlling the optical activity of halide perovskite materials through modulation of the coordination configurations of the metal ions is important. Herein, a novel manganese-based halide, specifically diaquatetrakis(methyldiphenylphosphine oxide)manganese(II) tetrachloridomanganate(II), [Mn(C 13 H 13 OP) 4 (H 2 O) 2 ][MnCl 4 ] or [Mn(MDPPO) 4 (H 2 O) 2 ][MnCl 4 ] (MDPPO is methyldiphenylphosphine oxide), was synthesized through the solvothermal reaction of MnCl 2 with the neutral molecule MDPPO. In this compound, [Mn(MDPPO) 4 (H 2 O) 2 ] 2+ acts as the cation, while [MnCl 4 ] 2− serves as the anion, enabling the co-existence of tetrahedral and octahedral structures within the same system. Remarkably, the compound exhibits efficient red-light emission at 662 nm, distinct from the green-light emission typically observed in Mn X 4 -based halides. Theoretical calculations show that the red emission comes from the charge transfer from the MDPPO to the Mn 2+ of [MnCl 4 ] 2− . This work provides a new perspective for the design and synthesis of red-light-emitting manganese-based halides with unique structures.