Thermoinduced structural-transformation and luminescent conversion in hybrid manganese halides

Abstract We report here the synthesis of hybrid manganese halide crystals, (C 4 H 7 N 2 )MnCl 3 · H 2 O and (C 4 H 7 N 2 ) 2 MnCl 4 , by using the same organic ligand 2-methylimidazole. Upon heating treatment, the red-emissive (C 4 H 7 N 2 )MnCl 3 · H 2 O crystal is structurally transformed into green-emissive (C 4 H 7 N 2 ) 2 MnCl 4 crystal in situ . The crystal structural analysis reveals that the [MnCl 5 · H 2 O] 3− octahedra chains decompose into mono [MnCl 4 ] 2− tetrahedra, accompanied by the departure of H 2 O molecules. Upon cooling in air or water vapor, the crystal structure and luminescence of (C 4 H 7 N 2 ) 2 MnCl 4 are transformed to those of (C 4 H 7 N 2 )MnCl 3 · H 2 O. The in situ conversion of luminescence between (C 4 H 7 N 2 )MnCl 3 · H 2 O and (C 4 H 7 N 2 ) 2 MnCl 4 provides new insight into the potential application of hybrid manganese halides.