Synthesis,Crystal Structures And Properties Of Manganese(Ⅱ) Complexes Based On Ionic Liquids

In this paper,six low dimensional single crystals of ionic liquid/manganese（Ⅱ）complexes were synthesized by slow evaporation method,where the halogenated imidazole/pyridine ionic liquids（1-methyl-imidazole halides:[MIM]X;N-ethyl-pyridine halides:[Epy]X）and manganese halides tetrahydrate（Mn X₂·4H₂O）were used as reactive raw materials.The structure and properties of single crystals were tested,and the crystal structure,stability and luminescence properties of the complexes were studied in detail,and differences of crystal structure and luminescence properties of homologous complexes were also discussed.The specific research work was as follows:Part 1.Synthesis,crystal structure and properties of Mn（Ⅱ）complexes based on imidazole ionic liquidsAt room temperature,the molar ratio of [MIM]Cl:MnCl₂·4H₂O=1:1,[MIM]Br:Mn Br₂·4H₂O=1:1 and[MIM]Br:Mn Br₂·4H₂O=2:1 were weighed in blast drying oven at180°C to remove the crystal water to obtain solid raw materials.Then,the solid raw materials were dissolved in acetonitrile or ethanol to make saturated solution,and the complexes[MIM][MnCl₃（H₂O）]（1）,[MIM][Mn Br₃（H₂O）]（2）and[（MIM）₂][Mn Br₄]（3）were obtained by slow evaporation for several days.The X-ray diffraction results show that the 1 and 2 belong to different space groups P2₁/n and P2₁/c of the same monoclinic system,and the central Mn（Ⅱ）are all octahedral configurationand;and the 3 belongs to triclinic space group P1,and the central Mn（Ⅱ）has a tetrahedron configuration.Under the ultraviolet light(λ_ex=365 nm),complexes 1 and2 emitted red light,while the 3 emitted green light.Under the excitation of 374,376 and 368 nm,the fluorescence lifetimes of solid complexes 1-3 were 200.11,63.99 and 37.23μs,respectively,and their quantum yield were 23.52%,51.58%and 5.54%,respectively.Moreover,under the excitation of X-ray,all three crystals show the better X-ray fluorescence properties.Part 2.Synthesis,crystal structure and properties of Mn（Ⅱ）complexes based on pyridine ionic liquidsAt room temperature,the molar ratio of [Epy]Cl:MnCl₂·4H₂O=2:1,[Epy]Br:Mn Br₂·4H₂O=2:1 and[Epy]I:Mn Br₂·4H₂O=2:1 were weighed in blast drying oven at180°C to remove the crystal water to obtain solid raw materials.Then,the solid raw materials were dissolved in acetonitrile to make saturated solution,and the complexes[（Epy）₂][MnCl₄]（4）,[（Epy）₂][Mn Br₄]（5）and[（Epy）₂][Mn Br₂I₂]（6）were obtained by slow evaporation for several days.The X-ray diffraction results show that all three complexes belong to monoclinic system,the 4belongs to P2₁ space group,the 5 and 6 belongs to C2/c space group,and all three crystals have a tetrahedral configuration.Under the UV light(λ_ex=310 nm nm),all three complexes emit green light,and the 5 emits a harsh green light.Under the excitation of 294,325 and 332 nm,the fluorescence lifetimes of solid complexes 4-6 were 384.43,187.83 and 58.85μs,respectively,and their quantum yield were 11.56%,81.80%and 58.29%,respectively.With the excitation of X-ray,all three complexes exhibit prominent X-ray fluorescence performance,of which the 5 has the best performance.In addition,centimeter-sized single crystal 5 was grown through bottom seed-solution temperature-lowering method in the crystallizing dish.