Nano-dimensional square grid, helix chain, interpenetrated double layer, and chain of ring structures in new cobalt(II) metal–organic polymers based on 4,4′-oxybis-(benzoic acid) and 1,n-bis(imidazol-l-yl-methyl)benzene (n = 2, 3, 4)

Abstract

Four cobalt(II) coordination polymers, [Co₂(oba)₂(1,2-bix)₂]_n (1), [Co(oba)(1,3-bix)]_n (2), {[Co₄(oba)₄(1,4-bix)₄]·6H₂O}_n (3), and {[Co₆(oba)₆(1,4-bix)₆]·2H₂oba·3DMF·11H₂O}_n (4), where H₂oba = 4,4′-oxybis(benzoic acid), DMF = N,N-Dimethyl formamide, and 1,n-bix = 1,n-bis(imidazol-l-yl-methyl)benzene (n = 2, 3, 4), have been synthesized. These compounds were structurally characterized by single-crystal X-ray crystallography, IR spectroscopy, and thermogravimetric analysis. Compound 1 exhibits a 2-D nano square grid (4,4) network, while 2 features a 2-D structure with two distinct left- and right-handed helical chains. Compound 3 possesses a doubly interpenetrated double-layered framework structure. The structure of 4 is comprised of 1-D chains of rings. The structural differences reveal that the flexible dicarboxylate and neutral bis(imidazole) are effective building blocks in constructing coordination polymers with diverse architectures.

Keywords:

• Cobalt(II)
• Metal–organic polymers
• 4,4′-Oxybis(benzoic acid)
• Nano-dimensional square grid

Acknowledgments

This work was supported by the Nation Natural Science Foundation of China (grant nos. 21271143 and 21171133), the Opening Foundation of Zhejiang Provincial Top Key Discipline (No. 100061200132), and Tarbiat Modares University.