Syntheses, structures, and fluorescent properties of four Co(II) coordination polymers based on 5-hydroxyisophthalic acid and structurally related bis(benzimidazole) ligands

Abstract

Four cobalt(II) coordination polymers, {[Co(HO-BDC)(bbp)]}n (1), {[Co(HO-BDC)(bmbp)2]·(H2O)2}n (2), {[Co(HO-BDC)(bbb)]}n (3), and {[Co2(HO-BDC)2(bmbb)2]·(H2O)3}n (4), where HO-H2BDC = 5-hydroxyisophthalic acid, bbp = 1,3-bis(benzimidazol-1-yl)propane, bmbp = 1,3-bis(2-methyl-benzimidazol-1-yl)propane, bbb = 1,4-bis(benzimidazol-1-yl)butane, and bmbb = 1,4-bis(2-methyl-benzimidazol-1-yl)butane, have been synthesized and characterized by elemental analyses, IR spectra, single-crystal X-ray diffraction, thermogravimetric analyses, and fluorescence properties. Compounds 1 and 3 are 4-connected 2-D networks with (44·62) topology. Compound 2 is a 1-D chain, while 4 features a 1-D ladder. These 1-D and 2-D complexes are further connected by hydrogen bonds to form 3-D supramolecular architectures. Complexes 1–4 showed very strong yellow luminescence emission.