Our research interests lie in the broad area of supramolecular chemistry. Research in the group has generally focused on various assembly aspects of calix[n]arenes possessing different upper-rim functionality. We form challenging and rare supramolecular architectures that include both non-covalent and metal-organic nanotubules. Recent research has also focused on the formation of novel polynuclear metal clusters with calix[n]arenes as cluster supports. These molecules are extremely versatile and have afforded a degree of control over supramolecular coordination chemistry.
1. Self-Assembly of p-Carboxylatocalixarenes
We have been developing our ability to control non-covalent assembly of the p-carboxylatocalixarenes, and have discovered facile ways to both form and modulate (FIgure 1) the solid state packing of challenging nanotubular arrays. These architectures show a degree of tolerance towards variation in the pyridine template used in nanotube formation.
Figure 1. Modulation of the spacing between self-assembled p-carboxylatocalixarene nanotubes by introduction of functionality and use of an appropriate template agent.
2. Metal-Directed Assembly of p-Carboxylatocalixarenes
We have developed new building blocks that induce the formation of novel metal-organic nanotube structures that possess large solvent-filled channels (Figure 2).Current developments in this area are focusing on controlling pore diameter and shape for potential application of these systems.
Figure 2. Space-filling representation of metal-organic p-carboxylatocalixarene nanotubes packing to afford large solvent channels in the solid state.
3. Calix[n]arenes as Cluster Supports
We have been investigating the formation of novel polynuclear transition, lanthanide and 3d-4f cluster motifs using calix[n]arenes as supports. These assemblies can behave as Single Molecule Magnets (SMMs) or magnetic refrigerants, and 3d-4f systems can be tuned accordingly through the choice of lanthanide employed in synthesis (for example see Figure 3). The shape and versatility of the larger calixarenes is useful in the assembly of new clusters from common cluster building block fragments.
Figure 3. Calixarene-supported MnIII4LnIII4 system that behaves as an SMM or magnetic refrigerant depending on the lanthanide present.