Syntheses, structures and properties of copper(II) and cobalt(II) metal–organic frameworks based on R-isophthalate (R = –CH3 or –C(CH3)3) and 1,1′-(1,4-butanediyl)bis(imidazole) ligands

Three new complexes [Cu2(mip)2(bbi)]n (1), {[Cu2(tbip)2(bbi)2(H2O)]·2H2O}n (2) and {[Co2(tbip)2(bbi)2]·2H2O}n (3), were prepared through hydrothermal reactions of Cu(II) and Co(II) acetate with H2mip or H2tbip (H2mip = 5-methyl isophthalic acid and H2tbip = 5-tert-butyl isophthalic acid) and the flexible ligand bbi (bbi = 1,1′-(1,4-butanediyl)bis(imidazole)). All these complexes were structurally characterized by elemental analysis, IR spectroscopy and X-ray single-crystal diffraction. Complex 1 exhibits a 3D network, which are constructed from 2D carboxylate layer and bbi pillar. Complex 2 possesses a 2D layer structure, and exists extensive hydrogen-bonding interactions, while complex 3 is constructed from 2D layers which consists of alternating left- and right-handed helical chains, and further assembled to form a 3D framework by hydrogen-bonding interactions. The thermal stabilities of the corresponding complexes have been briefly investigated. In addition, dominant antiferromagnetic coupling was observed in complex 1.