Synthesis, structures and properties of a series of manganese coordination complexes constructed from dicarboxylic fluorene derivatives

Assembly reactions of 9,9-diethylfluorene-2,7-dicarboxylic acid (H2DFDC) and Mn(CH3COO)2·4H2O or MnCl2·4H2O by tuning of various secondary ligands such as 2,2′-bipyridine (2,2′-bpy), 4,4′-bipyridine (4,4′-bpy) or 1,3-bis(4-pyridyl)propane) (bpp), gave rise to four complexes {[Mn2(DFDC)2(DMF)2]·H2O}n (1), [Mn(DFDC)(2,2′-bpy)]n (2), {[Mn2(DFDC)2(4,4′-bpy)2]·2CH3OH}n (3), and {[Mn4(DFDC)4(bpp)2(CH3OH)3 (H2O)3]·3(CH3OH)·3(H2O)}n (4). Single crystal X-ray diffraction analysis reveal that complex 1 is three dimensional structure with rhombic channels filled by guest water molecules; 2 presents a close-packed structure with high thermal stability; 3 exhibits a three dimensional framework with micro-porous channels filled by guest methanol molecules and 4 is a two-dimensional structure. The photoluminescent properties of 1–4 have been studied, respectively, showing that the Mn(II) ions, accessorial organic ligands or crystal structures exert important influences on the photoluminescence emissions of H2DFDC ligands. Thermogravimetric analysis show that the complexes have remarkably high thermal stability. Magnetic susceptibility measurements have been finished and discussed for the complexes.

Assembly of 9,9-diethylfluorene-2,7-dicarboxylic acid and Mn(II) salts by tuning of various accessorial ligands resulted in four manganese complexes with different topological frameworks. Figure optionsDownload as PowerPoint slideHighlights
► Four manganese complexes based on 9,9-diethylfluorene-2,7-dicarboxylic acid were obtained.
► The complexes were structurally characterized by single-crystal X-ray diffraction.
► The complexes 1–4 display different topological structures.
► Thermogravimetric analysis show the complexes have remarkably high thermal stability.