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Issue 24, 2007
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Framework materials assembled from magnesium carboxylate building units

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Four coordination polymers containing magnesium metal nodes and di- or tricarboxylic acid organic connectors have been synthesised and structurally characterised with the aid of single crystal X-ray diffraction. Mg3(bdc)3(DMA)4 (1) and Mg3(bdc)3(EtOH)2 (2) were prepared from the 1 : 1 reaction of 1,4-benzenedicarboxylic acid (H2bdc) with Mg(NO3)2·6H2O in dimethylacetamide (DMA) or EtOH respectively. Both 1 and 2 contain tri-metallic magnesium carboxylate units which act as six-coordinate nodes for network construction. These tri-magnesium nodes are joined by the bdc ligands in 1 to give a 2D layered structure with coordinated DMA solvent molecules between the layers, whereas in 2 they stack end-on to form a novel 3D network containing 1D Mg carboxylate chains. Both 1 and 2 are moderately hygroscopic, and powder X-ray diffraction and thermogravimetric analysis studies show them to be interconvertible with Mg(bdc) and the hydrated complex Mg(bdc)(H2O)2via a series of solid-state reactions. Reaction of magnesium nitrate with 4,4′-biphenyldicarboxylic acid (H2bpdc) in DMA gives Mg3(bpdc)3(DMA)4 (3), which in contrast to 2 forms a ‘squashed’ 3D cubic network as a result of the increased distance between the trinuclear nodes necessitated by the longer bpdc ligands. Reaction of magnesium nitrate with the triangular organic building block 1,3,5-tricarboxylic acid (H3btc) in DMA gives crystals of Mg(H1.5btc)2/3(btc)1/3(DMA)2·(DMA)1/3 (4). Compound 4 contains mono-metallic metal nodes which assemble with the btc ligands to give 2D 63 tessellated layers with Mg-coordinated DMA molecules lying perpendicular to the layers. Some free DMA is also present in 4, sited in small pores between the layers.

Graphical abstract: Framework materials assembled from magnesium carboxylate building units

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Supplementary files

Article information

02 Apr 2007
25 Apr 2007
First published
18 May 2007

Dalton Trans., 2007, 2528-2535
Article type

Framework materials assembled from magnesium carboxylate building units

R. P. Davies, R. J. Less, P. D. Lickiss and A. J. P. White, Dalton Trans., 2007, 2528
DOI: 10.1039/B705028C

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