Molecular Tectonics of Entangled Metal-Organic Frameworks Based on Different Conformational Carboxylates Mixed with a Flexible N,N′-Type Ligand

On the basis of 1,4-bis(2-methyl-imidazol-1-yl)butane (bib), three new coordination polymers, namely, [Co(L1)(bib)](n) (1), {[Co(L2)(bib)]center dot 1.5H(2)O}(n) (2), and {[Co(L3)(bib)(0.5)]center dot H2O}(n) (3) (H(2)L1 = m-phthalic acid, H(2)L2 = glutaric acid, and H(2)L3 = 1,4-phenylenediacetic acid), have been synthesized and characterized. Polymer 1 features a three-dimensional (3D) 3-fold interpenetrating CdSO4 motif containing multiple interweaving helical chains. Compound 2 displays a 3D 3-fold interpenetrating 3-connected ThSi2 architecture with intriguing pseudo-Borromean links. Complex 3 shows a 3D 2-fold interpenetrating Pcu net. The results reveal that the dicarboxyl building blocks with different conformations play a significant role in promoting the diversity of the observed structural motifs. In addition, the magnetic property of 3 is also studied.