Effect of pH/metal ion on the structure of metal-organic frameworks based on novel bifunctionalized ligand 4′-carboxy-4,2′:6′,4-terpyridine

Four novel coordination polymers, [Cd-2(ctpy)(4)](n)center dot 2nH(2)O (1), [Cd-2(ctpy)(2)(ox)](n) (2), [Zn(ctpy)(ox)(0.5)](n)center dot 0.5nH(2)O (3) and [Cu-2(ctpy)(2)(ox)](n) (4), (Hctpy = 4'-carboxy-4,2':6',4 ''-terpyridine H(2)ox = oxalic acid), have been hydrothermally synthesized and characterized by elemental analysis, IR, single crystal X-ray diffraction and thermogravimetric analyses. Compound 1 is a new two-fold interpenetrating (3,5)-connected 3D framework with Schlafli symbol (6(3))(6(9).8). Compound 2 displays an unusual three-dimensional coordination network which exhibits an intriguing (4,5)-connected binodal new topological net with Schlafli symbol (4(2).6(3).8)(4(2).6(5).8(3)). Compound 3 features a two-fold interpenetrating (3,4)-connected 3D framework with the fsc topological net and the Schlafli symbol (6(3))(6(5).8). Compound 4 is a three-fold interpenetrating (3,4)-connected 3D framework with dmc topological net and Schlafli symbol (4.8(2))(4.8(5)). Interestingly, compounds 1-4 were obtained under similar reaction conditions. The structural diversity of compounds 1 and 2 may illustrate the marked effect of pH on the reaction solution. And the diversity structures of the compounds 2-4 may illustrate the marked effect of the metal ion on the reaction solution. Moreover, the fluorescent property of compounds 1-3 as well as the adsorption properties of 3 are also investigated.