Structural characterization of three semi-rigid tetracarboxylate-containing transition-metal coordination polymers.

Under hydro(solvo)thermal conditions, the reactions between transition-metal salts and tetracarboxylic acid molecules, with the assistance of organic base molecules, created three new coordination polymers, namely [H 2 (bpp)] 2 [Zn 2 (sph) 2 ]·H 2 O (sph = 4,4′-sulfonediphthalate, bpp = 1,3-bis(piperidyl)propane) 1 , [H 2 (bpp)] 2 [Ni 2 (oph) 2 (H 2 O) 2 ]·2H 2 O (oph = 4,4′-oxydiphthalate) 2 and [H 2 (bpe)] 2 [Ni(Hfph) 2 (bpe)] (bpe = 1,2-bis(pyridyl)ethylene; fph = 4,4′-(hexafluoroisopropylidene)diphthalate) 3 . X-ray single-crystal diffraction analysis reveals that (i) in 1 , the diprotonated bpp molecule acts as a templating agent. The quadruple-bridged sph molecules propagate the tetrahedral Zn 2+ ions into a 2-D layer network in 1 , where two types of circle loops are found; (ii) in 2 , the bpp molecule is also diprotonated. The triple-bridged oph molecules extend the octahedrally coordinated Ni 2+ ions into a 2-D layer network, in which a carboxylate-bridged Ni 2+ chain is observed; (iii) in 3 , the non-protonated bpe molecules link the Ni 2+ ions into a 1-D linear chain. The diprotonated bpe molecule acts as the countercation, while the fph molecule serves as the chelating ligand, existing in the form of Hfph 3− ; and (iv) the 2-D layers for 1 and 2 can both be simplified as a (4,4) net. The photoluminescence analysis reveals that 1 emits blue light with a maximum at 415 nm upon excitation at 355 nm. A magnetic property investigation indicates that antiferromagnetic interactions exist between the Ni 2+ ions in 2 . [ABSTRACT FROM AUTHOR]