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

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Abstract

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


Submitted
02 Apr 2007
Accepted
25 Apr 2007
First published
18 May 2007

Dalton Trans., 2007, 2528-2535
Article type
Paper

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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