Control over multifarious entangled Co(II) metal-organic frameworks: role of steric bulk and molar ratio of organic ligands

A series of entangled metal-organic polymers, namely [Co(bcp)(bib)](n) (1), {[Co(bce)(bib)(0.5)]center dot 2H(2)O}(n) (2), {[Co(oba)(bib)]center dot H2O}(n) (3), {[Co(oba)(bib)(0.5)]center dot 0.5H(2)O}(n) (4) and [Co(bce)(bi)(0.5)](n) (5) (H(2)bcp = 1,3-bis(4-carboxy-phenoxy) propane, H(2)bce = 1,2-bis(4-carboxy-phenoxy) ethane, H(2)oba = 4,4'-oxybis(benzoic acid), bib = 1,4-bis(2-methyl-imidazol-1-yl)butane and bi = 1,1'-(1,4-butanediyl)bis(imidazole)), have been synthesized and structurally characterized by single crystal X-ray diffraction. Complexes 1-5 display various coordination motifs with different entangled forms and conformations. The result clearly indicates that the steric bulk effect of ligands is significant in the direction of these networks, which is also well regulated by the molar ratio. In addition, the magnetic behavior of polymers 1-4 are investigated.