We are interested in conformational control: creating structures that fold or arrange themselves into persistent structures in solution. We make aromatic-rich ligands that can then be combined with metal ions to self-assemble into sequences that possess the information to adopt these conformations. These include cages, foldamers and interlocked architectures. We use strategies to control the way ligands come together at metal ions and maintain fidelity of connectivity.

We hope to develop synthetic systems with the defined spatial positioning of components and switchability that allows biological molecules like proteins to carry out regulated tasks. Dedicated research areas include:

Complementary pairings

Inspired by DNA, we have created a library of artificial pairings based on hydrogen-bonding and denticity. These pairings are predictable in their formation and exist orthogonally to one another in solution, allowing targeted design of larger assemblies. An example of this structural control can be seen below in our 2021 paper, where complementary ligand pairings control connectivity, and conformation in the generated sequences was driven through π-π interactions.

We have similarly used this approach to generate structural complexity in coordination cages, again exploiting ligand pairings with complementarity driven through denticity or hydrogen-bonding capability. This allowed us to synthesise the first example of a lantern-shaped cage that was comprised of four different low-symmetry ligands, with positional and orientational control.

Recently, we have extended this approach to include other foldameric, cyclic, and interlocked species, including the first example of a clippane formed under thermodynamic control, as well as another example of a trefoil entangled tetrahedron that can be reversibly converted to a dual macrocycle through elevated temperatures. We have also applied these pairings as part of a metallo-polymer to selectively scavenge Pd(II) ions.

Platinum(II) cages

Recently, the groups interest in lantern-shaped cages has led to work exploring methods of synthesising them efficiently with Pt(II). The use of this metal ion is a double-edged sword, as Pt(II) is very inert and so while the cages are very stable, they are also difficult to make. We now have a shelf-stable Pt(II) starting material and new methodology that allows use to rapidly synthesise these cages in as little as 1.5 hours, reporting the first examples of low-symmetry homoleptic, heteroleptic and multicavity cages in this class. We have since functionalised these acid-stable Pt(II) cages with protonatable cores, demonstrating their unique host-guest chemistry by reporting the first supramolecular system capable of positive reciprocal allostery, akin to cooperativity.

First row transition metal ion assemblies

Beyond square-planar metal ions, the group is keen to extend conformational control further across the periodic table, demonstrating this with lesser explored geometries and assemblies. Recently, this has led to our work on low-symmetry Fe(II) tetrahedra, where anisotropic extension of tris-bidentate ligands enabled the selective formation of homoleptic, low-symmetry tetrahedra – the first example of its kind. Similarly, we have reported a dynamic Fe(II) tetrahedron, where ligand flexibility and solvent interactions within the cavity, delicately shift the equilibrium between high-symmetry and low-symmetry forms dependent on the solvent present.