A series of metal–organic frameworks constructed with 2,2′-bipyridine-3,3′-dicarboxylate: Syntheses, structures, and physical properties

Abstract

To determine the influence of metal ion and the auxiliary ligand on the formation of metal–organic frameworks, six new coordination polymers, {[Mn 2(bpdc)(bpy) 3(H 2O) 2] · 2ClO 4 · H 2O} n ( 1), {[Mn(bpdc)(dpe)] · CH 3OH · 2H 2O} n ( 2), {[Cu(bpdc)(H 2O) 2]} n ( 3), {[Zn(bpdc)(H 2O) 2]} n ( 4), {[Cd(bpdc)(H 2O) 3] · 2H 2O} n ( 5), and {[Co(bpdc)(H 2O) 3] · 0.5dpe · H 2O} n ( 6) (H 2bpdc = 2,2′-bipyridine-3,3′-dicarboxylic acid, bpy = 2,2′-bipyridine, dpe = 1,2-di(4-pyridyl) ethylene), have been synthesized and characterized. Compound 1 forms 1D helical chain structure containing two unique Mn II ions. In 2, the bridging ligand dpe links Mn-bpdc double zigzag chains to generate a layer possesses rectangular cavities. In 3, bpdc 2− ligand connects to three metal centers forming a 2D network. Different from the above compounds, 4 displays a 1D double-wavelike chain. Compound 5 features a helical chain. Compound 6 also displays a helical chain with guest molecule dpe existing in the structure. These diverse structures illustrate rational adjustment of metal ions and the second ligand is a good method for the further design of helical compounds with novel structures and properties. In addition, the magnetic properties of 2, 3 and 6, the thermal stabilities and photoluminescence properties of 4 and 5 were also studied.