Novel two-dimensional Co(II) and Cd(II) coordination polymers with intriguing net topologies

Three new two-dimensional coordination polymers were constructed from 2,6-bis(imidazole-1-yl)pyridine (2.6-bip), terephthalic acid (1,4-bdcH₂), and M(NO₃)·nH₂O (M = Co, Cd). [M(2,6-bip)(1,4-bdc)] (1: M = Co; 2:M=Cd) were prepared under hydrothermal condition,whereas [Cd(2,6-bip)(1,4-bdc)·xDMF] (3) was obtained under solvothermal condition in DMF solvent. Single-crystal X-ray analyses revealed the first example of a 2D 4-connected net of 6⁶ topology in 1 and 2 and a rare 2D 4,5-connected net of 4,5 L20 topology in 3. All these complexes were thermally robust and emissive in solid-states. Thiswork confirmed the versatility of using hingelike 2,6-bip as a linker and the importance of solvent effect in the process of framework formation.