Dana L. Caulder

The self-assembly of a predesigned tetrahedral M4L6 supramolecular cluster

A remarkable selectivity on the basis of size is observed for the encapsulation of Et4N+ in the presence of Me4N+ and Pr4N+ by a predesigned [Ga4L6]12− homochiral tetrahedral cluster (L=bis-bidentate ligand). Immediate and quantitative stepwise replacement of R4N+ counterions in the cluster cavity is observed by 1H NMR spectroscopy (see below). The encapsulation of Et4N+ is also observed in the solid state.

Selbstorganisation eines supramolekularen tetraedrischen M4L6‐Clusters

Nicht zu gros und nicht zu klein sollte der Gast im Hohlraum sein: Der homochirale tetraedrische Cluster [Ga4L6]12− weist eine hohe Selektivitat fur den Einschlus von Et4N+ gegenuber Pr4N+ auf, das seinerseits eingeschlossenes Me4N+ verdrangt (L=zweifach zweizahniger Ligand); dieser sukzessive Austausch von R4N+-Ionen verlauft 1H-NMR-spektroskopischen Untersuchungen zufolge schnell und quantitativ (siehe unten). Der Einschlus von Et4N+ wurde auch im Festkorper nachgewiesen.

Exploiting Incommensurate Symmetry Numbers: Rational Design and Assembly of M2M3′L6 Supramolecular Clusters with C3h Symmetry

Mixed-metal mesocates [M2 Pd3 Br6 L6 ]4- (M=TiIV , SnIV ; L=4-diphenylphosphanyl-catecholate) have been synthesized, in which the two incommensurate symmetry elements generated by the different metal ions are linked by a rigid, bifunctional ligand to generate a C3h -symmetrical cluster (see picture).

Triple Helicate—Tetrahedral Cluster Interconversion Controlled by Host–Guest Interactions

A unique ligand design allows the formation of both an M2 L3 triple helicate and an M4 L6 tetrahedron (M=Ti, Ga; L=ligand based on 2,6-diaminoanthracene). Although the tetrahedron is entropically disfavored, a strong host-guest interaction with Me4 N+ is enough to drive the equilibrium towards the tetrahedron. Remarkably, the helicate can be quantitatively converted into the tetrahedron simply by addition of Me4 N+ (shown schematically).

Self‐Assembly of {2}‐Metallacryptands and {2}‐Metallacryptates

Reaction of H2L (1) with potassium or strontium hydride, or lanthanum(III) chloride, followed by iron(III) chloride, yielded the {2}-ironcryptates 2a–c. The mono-, di-, and trivalent guest cations are endohedrally encapsulated. In contrast, the dinuclear trispyridinium ironcryptand 2d was generated from the reaction of H2L (1) with only iron(III) chloride. The potassium metallacryptate 2a′ was formed from the triple-helicate 2d by addition of potassium carbonate. The new compounds 2b, 2c, and 2d were unequivocally characterised by X-ray diffraction analyses.