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 [H2(bpp)]2[Zn2(sph)2]·H2O (sph = 4,4′-sulfonediphthalate, bpp = 1,3-bis(piperidyl)propane) 1, [H2(bpp)]2[Ni2(oph)2(H2O)2]·2H2O (oph = 4,4′-oxydiphthalate) 2 and [H2(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 Zn2+ 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 Ni2+ ions into a 2-D layer network, in which a carboxylate-bridged Ni2+ chain is observed; (iii) in 3, the non-protonated bpe molecules link the Ni2+ 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 Hfph3−; 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 Ni2+ ions in 2.

Structural characterization of three new semi-rigid tetracarboxylate-containing transition-metal coordination polymers is reported. The photoluminescence behavior of the Zn2+ complex and the magnetic properties of the Ni2+ complex are investigated.Figure optionsDownload as PowerPoint slide