Construction of Entangled Coordination Polymers Based on M2+ Ions, 4,4′-{[1,2-Phenylenebis(methylene)]bis(oxy)}dibenzoate and Different N-Donor Ligands

Reactions of several transition metal [M = Mn(II), Cu(II), Zn(II), Co(II)] salts with 4,4'4-{[1,2-phenylenebis(methylene)]bis(oxy)}dibenzoic acid (H2L) and auxiliary N-donor ligands afforded a series of entangled coordination frameworks, [Mn2L2 (4,4'-bpy)(2)]-[Mn2L2(H2O)(2)]center dot 2H(2)O (1), [CuL(bbm)]center dot 0.5H(2)O (2), [CuL-(4,4'-bpy)(0.5)] (3), [Zn3L2(4,4'-bpy)(2)(HCOO)(2)] (4), [ZnL-(4,4'-bpy)](2)center dot H2O (5), [Co4L4(bpp)(2)]center dot DMF (6), [Co2L2(bbm)](2)center dot 2H(2)O (7), and [CoL(2,2'-bpy)] (8) [2,2'-bpy = 2,2'-bipyridine; 4,4'-bpy = 4,4'-bipyridine; bbm = 1,4-di(1H-imidazol-1-yl)benzene; bpp = 1,3-bis(4-pyridyl)propane]. Their structures were characterized by elemental analysis, IR spectra, and TG analysis and further determined by single-crystal X-ray diffraction analysis. Compound 1 has an uncommon 2D(layer) + 1D(chain) -> 3D framework, while 2 displays a 2-fold interpenetrated 3D framework. Compounds 3-5 show different entangled networks though they adopt the same 4,4'-bpy as the auxiliary ligand. Compounds 3 and 5 show 2-fold interpenetrated 2D networks, showing both polycatenane and polyrotaxane characters. Compound 4 possesses a 2D -> 3D polythreaded architecture. Compound 6 has a 3-fold interpenetrated 3D framework by using bpp as the second ligand. Compound 7 presents a 3D framework with a (4(4).6(2).8(8).12)(4(4).6(2))(8) topology. Compound 8 presents a ID helical chain constructed by linking [Co(2,2'-bpy)](2+) units via L ligands. The results provided an interesting insight into how metal ions, auxiliary N-donor ligands, and molar ratios of the components exert great impact on the formation of these entangled networks. The thermal and luminescent properties of 1-8 in solid state at ambient temperature were also investigated.