Novel long bipyridine-type linking ligands containing an intervening naphthalene fragment: [Zn(L 1)(NO 3) 2], [Zn(L 2)(NO 3) 2], and [Cd(L 1) 1.5(NO 3) 2] (L 1 = (4-py)–CH [dbnd]N–C 10H 6–N [dbnd]CH–(4-py); L 2 = (3-py)–CH [dbnd]N–C 10H 6–N [dbnd]CH–(3-py))

Abstract

Novel bipyridine-type linking ligands L 1 ((4-py)–CH N–C 10H 6–N CH–(4-py)) and L 2 ((3-py)–CH N–C 10H 6–N CH–(3-py)), a pair of isomers due to possessing different pairs of terminal pyridyl groups, were prepared by the Schiff-base condensation. In ligand L 1 , 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 L 2 is 14.2 Å, with the nitrogen donor atoms at the meta positions (3,3′). 1-D zigzag-chain coordination polymers [Zn( L 1 )(NO 3) 2] ( 1) and [Zn( L 2 )(NO 3) 2] ( 2) were prepared by reactions of Zn(NO 3) 2 · 6H 2O with ligands L 1 and L 2 , respectively, by solution diffusion. Polymer 3, [Cd( L 1 ) 1.5(NO 3) 2], prepared from Cd(NO 3) 2 · 4H 2O and L 1 , exhibits a 1-D ladder structure, whose repeating ladder unit consists of four Cd metals and four L 1 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.