Construction of Metal‐Organic Frameworks with the Pyridine‐3,5‐dicarboxylate Anion and Bis(imidazole) Ligands: Synthesis, Structure, and Thermostability Studies

Three novel metal‐organic polymers, namely, [Ni(L 1 ) 0.5 (3,5‐pdc)(μ‐H 2 O)] · H 2 O ( 1 ), [Co(L 2 )(3,5‐pdc)] · 2H 2 O ( 2 ), and [Co(L 3 )(3,5‐pdc)(μ‐H 2 O)] · H 2 O ( 3 ) [3,5‐pdc = pyridine‐3,5‐dicarboxylate, L 1 = 1,4‐bis(imidazol‐1‐ylmethyl)benzene, L 2 = 1,1′‐(1,4‐butanediyl)bis(imidazole), and L 3 = 1,1′‐(1,4‐hexanediyl)bis(imidazole)], have been hydrothermally synthesized and characterized by single‐crystal X‐ray diffraction (XRD), thermogravimetric (TG) analysis, and elemental analysis (EA). Polymers 1 and 2 have the identical 2D [M(3,5‐pdc)] sheet skeleton, however, different bis(imidazole) ligands cause 1 to have a 2D (3,4)‐connected double‐layer net featuring the (6 3 )(6 4 · 8 2 ) topology symbol and 2 to have a 2D (3,5)‐connected net characterized by the (3 5 2 )(3 2 · 5 3 · 6 4 · 7) topology symbol. They are both extended to 3D supramolecular frameworks through the O–H ··· O hydrogen bonds. In particular, in 2 there exists a four‐membered Z‐shape water cluster. The Co ions in 3 are connected by 3,5‐pdc and L 3 to give rise to a complicated 3D framework that can be described as a (3,5)‐connected (4 2 · 5)(4 2 · 6 3 · 8 2 · 10 2 · 12) network. In addition, the thermal analysis of these three complexes has been measured and discussed.