Four Low-Dimensional Cobalt(II) Coordination Polymers Based on a New Isophthalic Acid Derivative: Syntheses, Crystal Structures, and Properties

A isophthalic acid derivative, 5-(4'-methylphenyl)isophthalic acid (CH3C6H4-H(2)ip), has been prepared. Reaction of CH3C6H4-H(2)ip with Co(Ac)(2)center dot 4H(2)O and four N-donor ancillary ligands gave four new coordination polymers, {[Co(CH3C6H4-ip)(bip)]center dot 2H(2)O}(n) (1), {[Co-2(CH3C6H4-ip)(2)(bib)]center dot H2O}(n) (2), {[Co(CH3C6H4-ip)(bpe)(0.5)(H2O)]center dot H2O}(n) (3), {[Co(CH3C6H4-ip) (bipy)(0.5)]}(n) (4), [bip =1, 5-bis(imidazol)pentane, bib = 1, 4-bis(imidazol)butane, bpe = 1, 2-bi(4-pyridyl)ethene, bipy = 2, 2'-bipyridyl]. Complexes 1-4 were structurally characterized by elemental analysis, infrared spectra (IR), and X-ray single-crystal diffraction. These complexes all display low-dimensional features. Complex 1 exhibits an extended polythreaded network based on two-dimensional (2D) layers that are connected by CH3C6H4-ip and bip ligands. Complex 2 shows a 2D layer containing dinuclear paddle-wheel [Co-2(CO2)(4)] secondary building units (SBUs). Complex 3 possesses a 2D layer and further stacks via hydrogen bonding interactions to generate a three-dimensional supramolecular architecture. Complex 4 shows a one-dimensional linear chain bridged by CH3C6H4-ip. These results suggest that both CH3C6H4-ip and N-donor coligands have a significant effect on the final structures. Variable-temperature magnetic susceptibility measurements reveal the existence of antiferromagnetic interactions in 2 and ferromagnetic interactions in 3, respectively.