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Co-doping of the MOF 3∞[Zn(2-methylimidazolate-4-amide-5-imidate)] (IFP-1 = Imidazolate Framework Potsdam-1) with luminescent Eu3+ and Tb3+ ions presents an approach to utilize the porosity of the MOF for the intercalation of luminescence centers and for tuning of the chromaticity to the emission of white light of the quality of a three color emitter. Organic based fluorescence processes of the MOF backbone as well as metal based luminescence of the dopants are combined to one homogenous single source emitter while retaining the MOF's porosity. The lanthanide ions Eu3+ and Tb3+ were doped in situ into IFP-1 upon formation of the MOF by intercalation into the micropores of the growing framework without a structure directing effect. Furthermore, the color point is temperature sensitive, so that a cold white light with a higher blue content is observed at 77 K and a warmer white light at room temperature (RT) due to the reduction of the organic emission at higher temperatures. The study further illustrates the dependence of the amount of luminescent ions on porosity and sorption properties of the MOF and proves the intercalation of luminescence centers into the pore system by low-temperature site selective photoluminescence spectroscopy, SEM and EDX. It also covers an investigation of the border of homogenous uptake within the MOF pores and the formation of secondary phases of lanthanide formates on the surface of the MOF. Crossing the border from a homogenous co-doping to a two-phase composite system can be beneficially used to adjust the character and warmth of the white light. This study also describes two-color emitters of the formula Ln@IFP-1a–d (Ln: Eu, Tb) by doping with just one lanthanide Eu3+ or Tb3+.
Cadmium(II) based 2D coordination polymer [Cd(L1)(2)(DMF)(2)] (1) (L1 = 4,5-dicyano-2-methylimidazolate, DMF = N,N'-dimethylformamide) and 2D cobalt(II)-imidazolate framework [Co(L3)(4)] (2) (L3 = 4,5-diamide-2-ethoxyimidazolate) were synthesized under solvothermal reaction conditions. The materials were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, powder X-ray diffraction measurement (PXRD) and single-crystal X-ray diffraction. Compound 1 has hexacoordinate Cd-II ions and forms a zigzag chain-like coordination polymer structure, whereas compound 2 exhibits a 2D square grid type structure. The thermal stability analysis reveals that 2 showed an exceptional thermal stability up to 360 degrees C. Also, 2 maintained its fully crystalline integrity in boiling water as confirmed by PXRD. The solid state luminescent property of 1 was not observed at room temperature. Compound 2 showed an independent high spin central Co-II atom.