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

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.