Two Co(II) complexes based on 6-(3-pyridyl)isophthalic acid ligand: Structures, stability and catalytic applications

Abstract

Two new coordination polymers, namely [Co(pip)(H2O)2]n (H2pip = 6-(3-pyridyl)isophthalic acid) (1) and [Co(pip)(bidmb)0.5]n (bidmb = 1,4-bis(1-imidazoly)-2,5-dimethylbenzene) (2), have been prepared under solvothermal conditions, and characterized by single-crystal X-ray diffraction, PXRD, elemental analyses, IR and TGA. Structure analysis reveals that complex 1 presented one dimensional (1D) ladder-like chain structures, which are further linked into a 3D supramolecular structure through hydrogen-bonds. Then, under the same synthetic conditions, complex 2 was obtained with a 3D “layer-pillar” structure when adding bidmb as the auxiliary pillar ligand. TGA and PXRD results reveal that both 1 and 2 possess relative high hydrothermal stability. In addition, the catalytic applications of obtained complexes were also investigated. It shows that 1 displayed superior catalytic behavior in both cycloaddition of carbon dioxide with epoxide and hydrogenation of 4-nitrophenol (4-NP) process, and could be reused for more than five times without obvious fading in activity. Excellent stability and recyclability make this new catalyst also attractive for other applications.