Exploiting Complementary Second-sphere Effects in Supramolecular Coordination Solids

In the design of extended supramolecular solids, reliable synthons are a valuable commodity. This work concerns the complementary second-sphere coordination interactions between a highly preorganized hexasulphonated ligand, L, and aquated metal ions. Four second-sphere inclusion complexes [M(H2O)6]2 L ·(S)3 (M/S: Mg/acetone, 1; Zn/acetone, 2, Mg/dioxane, 3; Zn/dioxane, 4) and three extended networks {[(M(H2O)3)2(L)]·(H2O)14.5}∞ (M=Cr, 5; Fe, 6; Al, 7) have been structurally characterized by X-ray crystallography. The second-sphere effects on the stabilization of the primary coordination sphere are illustrated by TGA experiments. In these assemblies, the potential of a new supramolecular synthon is illustrated, that being the complementary hydrogen-bonding interaction between cis-aquo ligands and sulphonate oxygen atoms.