Sean A. Dalrymple

Anion Exchange in the Channels of a Robust Alkaline Earth Sulfonate Coordination Network

The barium sulfonate network presented herein, [[Ba2(L)(H2O)5]Cl]infinity (1), represents the first metal sulfonate compound to possess a cationic framework. The network is layered with channels between pillaring ligands in which chloride ions reside. Compound 1 contracts slightly upon dehydration but retains its overall structural motif to 420 degrees C. Significantly, the chloride ions of the structure can be exchanged in 80% yield for fluoride ions in a facile manner. This exchange is quantified by elemental analyses, gravimetric determination, and 19F NMR spectroscopy. Confirmation of retention of structure is provided by standardized powder X-ray diffraction experiments. This last point is notable as the F-analogue of the structure is not attainable by a direct synthesis. These results illustrate one of the hallmark features of supramolecular chemistry, that a robust and functional framework can result through cooperative interactions between more weakly interacting units.

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.

Selective guest inclusion in a non-porous H-bonded host

A hydrogen-bonded host solid demonstrates reversible and selective guest inclusion, despite not having a porous interlayer.

Supramolecular encapsulation of hexaaquo metal ions by second sphere coordination

Two trianions of 1,3,5-tris(sulfomethyl)benzene each form six hydrogen bonds to the water molecules of octahedral [M(H2O)6]3+ cations to completely encapsulate the metal complexes via second sphere coordination.

An open channel coordination framework sustained by cooperative primary and secondary sphere interactions

A three-dimensional coordination solid is presented in which every metal ion is stabilized by both primary and secondary sphere interactions to form an open channel structure.