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′-{[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]·2H2O (1), [CuL­(bbm)]·0.5H2O (2), [CuL­(4,4′-bpy)0.5] (3), [Zn3L2(4,4′-bpy)2(HCOO)2] (4), [ZnL­(4,4′-bpy)]2·H2O (5), [Co4L4(bpp)2]·DMF (6), [Co2L2(bbm)]2·2H2O (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 2Dlayer + 1Dchain → 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 (44·62·88·12)­(44·62)­(8) topology. Compound 8 presents a 1D 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.