Synthesis, crystal structure and photoluminescent properties of four lanthanide 5-nitroisophthalate coordination polymers

Four new lanthanide coordination polymers, [Y(Hnip)(nip)(H2O)] center dot H2O (1), [Ln(Hnip)(mp)(H2O)(2)] center dot 2H(2)O [Ln = Eu(2), Tb(3)] and [Y(nip)2] center dot (H(2)4,4'-bpy)(0.5) (4) [5-nip = 5-nitroisophthalate, 4,4'-bpy = 4,4'-bipyridine], have been hydrothermally synthesized and structurally characterized. Compound 1 features novel lanthanide-carboxylate groups chains composed of. three samehanded helical strands intersecting each other through hinged lanthanide atoms, and these chains are cross-linked by phenylene moieties of carboxylate ligands into a 21) layer structure. Compounds 2 and 3 are isomorphous, and contain ID catenanelike Ln-O-C-O-Ln chains, which are interconnected by phenylene moieties into 2D layer structures. Compound 4, however, displays a 3D architecture sustained by strong hydrogen bonding interactions between the protonated 4,4'-bpy and the carboxyl oxygen atom from [Y-2(nip)(4)](2-) with 2D layer structure, and 4,4'-bpy as the guest molecules exist in bilayer channel. The studies for the thermal stabilities of the four compounds show that compound 4 is more stable than other compounds. Compound 2 emits characteristic red luminescence of Eu3+ ions at room temperature, and its luminescent lifetime and quantum efficiency has been determined. (C) 2008 Elsevier Inc. All rights reserved.