Thermoinduced structural-transformation and luminescent conversion in hybrid manganese halides

We report here the synthesis of hybrid manganese halide crystals, (C4H7N2)MnCl3 · H2O and (C4H7N2)2MnCl4, by using the same organic ligand 2-methylimidazole. Upon heating treatment, the red-emissive (C4H7N2)MnCl3 · H2O crystal is structurally transformed into green-emissive (C4H7N2)2MnCl4 crystal in situ. The crystal structural analysis reveals that the [MnCl5 · H2O]3- octahedra chains decompose into mono [MnCl4]2- tetrahedra, accompanied by the departure of H2O molecules. Upon cooling in air or water vapor, the crystal structure and luminescence of (C4H7N2)2MnCl4 are transformed to those of (C4H7N2)MnCl3 · H2O. The in situ conversion of luminescence between (C4H7N2)MnCl3 · H2O and (C4H7N2)2MnCl4 provides new insight into the potential application of hybrid manganese halides.