Influence of Water Content on the Self-Assembly of Metal−Organic Frameworks Based on Pyridine-3,5-dicarboxylate

A 0D discrete molecule [Co(3,5-pdc)(H2O)5]·2H2O (1) was obtained in quantitative yield from the reaction of CoCl2·6H2O and pyridine-3,5-dicarboxylate (3,5-pdc) in pure water solvent at ambient temperature. While a 1D zigzag
chain species, [{Co(3,5-pdc)(H2O)4}·H2O]n (2), was produced in a water-rich environment, a 2D layer compound,
[Co(3,5-pdc)(H2O)2]n (3), with a 63 topology was generated under a water-reduced condition and a 2D sheet structure,
[{Cu(3,5-pdc)(py)2}·H2O·EtOH]n (4), was formed under a water-poor condition. Compounds 1, 2, and 4 were
characterized by single-crystal X-ray diffraction analysis. The 1D zigzag chain 2 shows a recoverable collapsing
property. Compound 4 adopts a 2D sheet structure with a 4·82 topology, observed for the first time for the 3,5-pdc-related metal−organic frameworks. Water content was found to be an important factor in determining the
topologies of the products in the self-assembly of divalent metal ions (Co2+, Cu2+) and pyridine-3,5-dicarboxylate
under mild conditions.