Hydrogen Bond and π-π Interactions in a 3D Supramolecular Structure Containing 1D Helical Chains

The reaction of 2, 2'-bipyridine-6, 6'-dicarboxylic acid (H(2)bpdc) with zinc nitrate and different rare earth chlorides generates two novel three-dimensional supramolecules Zn(6-bpc)(2) center dot 2H(2)O (1) and Ce(bpdc)(2)center dot H2O (2) (6-Hbpc = 2, 2'-bipyridine-6-carboxylic acid). The left-and right-handed helical chains give rise to a 3D supramolecular framework through hydrogen-bond and weak pp interactions in complex 1. Interestingly, the decarboxylation occurred and the bpdc ligand was transformed into 6-bpc species under the hydrothermal reaction in the presence of Nd-III ions, while the decarboxylation did not occur when Ce-III ions were used. In the structure of 2, one central Ce(IV) atom coordinates to two bpdc ligands, resulting in a discrete molecule. These discrete units are further extended into a 3D supramolecular structure through intermolecular hydrogen bonds and pp interactions.