New examples of metal coordination architectures of 4,4'-sulfonyldibenzoic acid: Syntheses, crystal structure and luminescence

Seven metal-organic coordination polymers, namely [Cd(sfdb)(phen)(2)]n center dot 2nH(2)O (1), [Cd(sfdb)(bpy)(2)]n center dot nH(2)O (2), [Cu(sfdb)(phen)(H2O)]n center dot 0.5nH(2)O (3), [Zn(sfdb)(bpy)(H2O)]n center dot 0.5nCH(3)OH (4), [Cd(sfdb)(quin)](n) (5), [Cd-3(sfdb)(2)(Hsfdb)(2)-(phen)(2)](n) (6), and [Cd(sfdb)(bpy)](n) (7) [H(2)sfdb = 4,4'-sulfonyldibenzoic acid, phen = 1,10-phenanthroline, quin = 2,2'-biquinoline, bpy = 2,2'-bipyridine] have been synthesized according to the principles of crystal engineering and structurally characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction analyses. Compounds 1-3 form 1D zigzag chains. Two phen ligands chelate to one cadmium atom in 1, which is rare in similar polymers, while two 2,2'-bpy ligands coordinate one cadmium atom in 2. The zigzag chains in 3 propagate in two different directions (rotated by 75 degrees) that are assembled by supramolecular forces into an intriguing three-dimensional network. Complexes 4 and 5 form square -wave -like 1D chains, although the results indicate a transformation of 2,2'-bpy into quin during the course of the hydrothermal synthesis of compound 5. Compound 6 is a 1D grid-chain based on a linear trinuclear unit, and compound 7 shows a 1D double chain containing 28-membered rings with sfdb 2- ligands as bridges. Weak hydrogen bonding and intra- and/or intermolecular pi center dot center dot center dot pi stacking contacts in compounds 3-7 link the discrete 1D chains into high- dimensional supramolecular structures. The sfdb 2-ligand displays multiple coordination modes in these seven complexes. Complexes 1, 2, and 4-7 show blue photoluminescence at room temperature. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).