Self-assembly synthesis of precursors to potential open framework alkali earth metal-organic complexes

The synthesis and crystal structures of a series of six magnesium pyridinecarboxylic and dicarboxylic acid complexes are reported. These complexes have been prepared to establish the nature of the hydrogen-bonding within this series and to investigate the potential of using these complexes as precursors in the self-assembly of network materials. Two Mg picolinic acid complexes (Mg1, Mg2) display a 1:2 metal:ligand ratio and are polymorphic. A Mg isonicotinic acid complex (Mg3) is a constitutional isomer of Mg1 and Mg2, while a 1:1 Mg picolinic acid complex (Mg4) is also reported and compared to the other members of the series. The set of complexes reported is completed by the synthesis and structural characterisation of two complexes containing the 2,4- pyridinedicarboxylic acid (2,4pdca) ligand, both a 1:1 (Mg5) and 1:2 (Mg6) Mg 2,4pdca acid complex, in which the presence of the additional carboxylate functionality provides clearer potential to form materials with extended network structures.