Homochiral frameworks derived from magnesium, zinc and copper salts of l-tartaric acid

Abstract

Five metal-organic frameworks derived from l-tartarate ( l-tart=C 4H 4O 6) and the divalent metal ions magnesium, zinc or copper have been prepared and structurally characterized. The frameworks were prepared from the reaction of potassium l-tartrate [KC 4H 5O 6] with the appropriate metal salt in water solutions. The magnesium compound [Mg( l-tart)(H 2O)⊃1.5H 2O], 1, crystallizes as a two-dimensional 6 3 sheet structure. The addition of the divergent linker molecules 4,4′-bipyridine (bipy) or trans-1,2-bispyridylethylene (bpe) to systems involving Zn 2+ and Cu 2+ results in the formation of the homochiral three-dimensional structures [Zn 2( l-tart)2(biyp)(H 2O)⊃5.25H 2O], 2, [Cu( l-tart)(bipy)⊃2.33H 2O], 3, and [Cu( l-tart)(bpe)⊃8H 2O], 5. Removal of solvent water molecules from 3 resulted in [Cu( l-tart)(bipy)⊃0.2H 2O], 4. Similar experiments on 2 and 5 resulted in breakdown of the frameworks, illustrating the dependence of the stability of these structures on the guest water molecules. This study reports the structures of two new topological types of binodal nets.