Crystal engineering of the coordination architecture of metal polycarboxylate complexes by hydrothermal synthesis: Assembly and characterization of four novel cadmium polycarboxylate coordination polymers based on mixed ligands

Four novel compounds, [Cd(tp)(bpp)](n) (1), [Cd(tp)(bpy)](n) (2), [{Cd-4(bpa)(4)(bpy)(6)}(.)(bpy)(0.5)(.)7H(2)O](n) (3) and [Cd-2{(Htp)(tp)(1.5)}(bpe)](n) (4) [tp = terephthalate, bpp = 1,3-bis(4-pyridyl)propane, bpy = 4,4'-bipyridine, bpa = 4,4'-biphenyldicarboxylate, bpe = 1,2-bis(4-pyridyl)ethane], of cadmium(II) polycarboxylate coordination polymers based on mixed ligands were obtained by a hydrothermal method. Complex I (C21H18CdN2O4) crystallizes in the orthorhombic Pbca space group [a = 11.9401(0) Angstrom, b = 16.8148(3) Angstrom, c = 20.2743(3) Angstrom, and Z = 8]. Complex 2 (C18H12CdN2O4) belongs to the monoclinic C2/m space group [a = 20.299(3) Angstrom, b = 10.720(1) Angstrom, c = 11.764(2) Angstrom, beta = 110.944(2)degrees, and Z = 6]. Complex 3 (C121H98Cd4N13O23) belongs to the monoclinic P2(1)/c space group [a = 23.2208(0) Angstrom, b = 11.8103(1) Angstrom, c = 45.4670(6) Angstrom, beta = 104.516(1)degrees, and Z = 4]. Complex 4 (C32H23Cd2N2O10) belongs to the monoclinic P2(1)/n space group [a = 6.9896(1) Angstrom, b = 22.6294(1) Angstrom, c = 19.7738(3) Angstrom, beta = 99.380(1)degrees, and Z = 4]. The Cd-II centers in the four compounds are bridged by mixed polycarboxylate ligands with bpy and related species to form the twofold parallel interpenetration topology of an undulating 2D 4(4) net for 1, a twofold interpenetration topology of a 3D alpha-Po net for 2, a fourfold interpenetration topology of a 3D 5-connected borazone 4(6)6(4) net for 3 and an interesting 3D spiral pipe-like structure with a bolt for 4. These four compounds exhibit strong fluorescent emissions at 549 and 582 nm (lambda(ex) = 532 nm) for 1,493 nm (lambda(ex) = 360 nm) for 2,413 and 424 nm (lambda(ex) = 315 nm) for 3 and 350 nm (lambda(ex) = 220 nm) for 4 in the solid state at room temperature. These are novel structural topologies and could be significant in the field of photoactive materials. (C) Wiley-VCH Verlag GmbH & Co. KGdA, 69451 Weinheim, Germany, 2004.