Synthesis and characterization of two unsquare 4-connected 2D coordination polymers with helical character

•Two coordination complexes with interesting 2D unsquare (4, 4)-connected net have been synthesized.•The 2D layers of complexes 1 and 2 have chiral and nonchiral features, respectively.•Both complexes have the helical character with 1D [M2(bix)2]∞ (M = NiII and CoII) chain.

Under hydrothermal conditions, two 2D coordination polymers based on methylenediisophthalic acid (H4L) and 1,2-bis(imidazole-1-ylmethyl)benzene/1,3-bis(imidazole-1-ylmethyl)benzene (o-bix/m-bix) connectors were prepared and characterized by single crystal X-ray diffraction, IR and TG analysis. The structural analysis shows that complexes 1–2 have interesting unsquare 4-connected topological nets. Complex 1 has the Schläfli symbol (32.4.62.7)2(32.62.72) with the distorted β-W net and complex 2 has the seldom reported Schläfli symbol (3.4.5.62.7)2(3.42.52.7). Moreover, there exist 1D helical chains [M2(bix)2]∞ (M = NiII and CoII) in 2D chiral layer of 1 and 2D nonchiral layer of 2.

Graphical abstractTwo 2D coordination complexes with helical character based on mixed ligands have been synthesized and both can be simplified to be interesting unsquare 2D (4, 4)-connected nets.Figure optionsDownload full-size imageDownload as PowerPoint slide