Novel long bipyridine-type linking ligands containing an intervening naphthalene fragment: [Zn(L1)(NO3)2], [Zn(L2)(NO3)2], and [Cd(L1)1.5(NO3)2] (L1 = (4-py)–CHN–C10H6–NCH–(4-py); L2 = (3-py)–CHN–C10H6–NCH–(3-py))

Novel bipyridine-type linking ligands L1 ((4-py)–CHN–C10H6–NCH–(4-py)) and L2 ((3-py)–CHN–C10H6–NCH–(3-py)), a pair of isomers due to possessing different pairs of terminal pyridyl groups, were prepared by the Schiff-base condensation. In ligand L1, the N⋯N separation between the terminal pyridyl groups is 16.0 Å, with their nitrogen donor atoms at the para positions (4,4′). The corresponding N⋯N separation in ligand L2 is 14.2 Å, with the nitrogen donor atoms at the meta positions (3,3′). 1-D zigzag-chain coordination polymers [Zn(L1)(NO3)2] (1) and [Zn(L2)(NO3)2] (2) were prepared by reactions of Zn(NO3)2 · 6H2O with ligands L1 and L2, respectively, by solution diffusion. Polymer 3, [Cd(L1)1.5(NO3)2], prepared from Cd(NO3)2 · 4H2O and L1, exhibits a 1-D ladder structure, whose repeating ladder unit consists of four Cd metals and four L1 ligands to create a large 76-membered ring with dimensions of 20.8 × 20.8 Å. All products were structurally characterized by X-ray diffraction.

Novel bipyridine-type linking ligands L1 ((4-py)–CHN–C10H6–NCH–(4-py)) and L2 ((3-py)–CHN–C10H6–NCH–(3-py)) were prepared by the Schiff-base condensation. Their zinc and cadmium coordination polymers [Zn(L1)(NO3)2] and [Zn(L2)(NO3)2], and [Cd(L1)1.5(NO3)2] were prepared. The imine nitrogen atoms do not bind to the metal in all polymers.Figure optionsDownload as PowerPoint slide