Tetrabromoterephthalic Acid Research Articles

Lanthanide (La III/Ho III)-oxalate open framework materials formed by in situ ligand synthesis

Two new lanthanide-organic open framework materials, {La(ox) 0.5( μ-OH) 2( μ-H 2O)(H 2O) 2} n ( 1) and {[Ho(ox) 1.5(H 2O) 3](en)} n ( 2) (ox = oxalate dianion and en = ethylenediamine) have been synthesized and structurally characterized. Both the frameworks obtained from in situ synthesis of oxalate ligand from dicarboxylic acid (2,5-dihydroxyterephthalic acid for 1 and tetrabromoterephthalic acid for 2) and lanthanide ions (Ln III) at high temperature. The probable route to the formation of oxalate ligand is the decarboxylation from the corresponding dicarboxylic acid and consecutive reductive coupling catalyze by the corresponding Ln III ions. Compound 1 is a 3D framework formed by pillaring of the oxalate ligand to two dimensional La–O–La inorganic layers, resulting 1D channels along the b-axis. Compound 2 is a 2D honeycomb like oxalate bridged framework of Ho III templated by the en molecules.

Cobalt(II), silver(I), and lead(II) tetrabromoterephthalates exhibiting the 1-D linear chain, 2-D CdCl 2-type layer, and 3-D penta-nodal mixed-connecting coordination frameworks

Reaction of tetrabromoterephthalic acid (H 2TBTA) with Co(OAc) 2, AgNO 3, or Pb(OAc) 2 under similar conditions affords three new coordination polymers {[Co(TBTA)(DMF) 2(H 2O) 2](DMF) 2} n ( 1), [Ag(TBTA) 0.5] n ( 2), and [Pb 2(TBTA) 1.5(OH)(DMF)] n ( 3). All these complexes have been characterized by elemental analysis, IR, powder X-ray diffraction, and TG-DTA techniques. Single-crystal X-ray diffraction reveals that complex 1 has a 1-D neutral coordination array in which the adjacent Co II centers are bridged by the TBTA spacers, whereas 2 displays a binodal CdCl 2-type coordination layer in which the Ag I ions and TBTA ligands function as 3- and 6-connected nodes, respectively. In the structure of 3, two types of Pb II ions are interconnected via the μ 4- and μ 5-TBTA ligands as well as the μ 3-hydroxyl ions to generate a complicated 3-D penta-nodal coordination framework with (3,4,5)-connectivity. These results clearly suggest that the metal centers with distinct binding tendencies are responsible for the remarkable structural diversity of such crystalline materials.

Solvent-regulated assembly of 1-D and 2-D Zn II coordination polymers with tetrabromoterephthalate

Two distinct coordination polymers [Zn(TBTA)(DMF) 2(CH 3OH) 2] n ( 1) and {[Zn(TBTA) 0.5(DMF)(OH)]-(H 2O)} n ( 2) have been prepared from the vapor diffusion reactions of Zn II nitrate with a rigid ligand tetrabromoterephthalic acid (H 2TBTA) under different solvent atmospheres. Both complexes have been characterized by elemental analysis, IR, powder X-ray diffraction, and TG-DTA techniques. Single crystal-X-ray diffraction studies reveal that 1 displays a 1-D linear motif with TBTA spacers whereas 2 presents a 2-D kgm network with the aid of hydroxyl spacers and 4-connected TBTA linkers.