Our research focuses on supramolecular chemistry, particularly self-assembly.

Specifically, we are interested in using relatively weak non-covalent interactions such as hydrogen bonding and halogen bonding to assemble complex/interesting/potentially useful 3D architectures. This encompasses aspects of host–guest chemistry, self–assembly and crystal engineering.

Specific areas of research are described in more detail below, with some selected references provided.

Hydrogen bonded frameworks:
We have developed a (relatively) general route to a large family of supramolecular frameworks assembled through charge-assisted amidinium···carboxylate hydrogen bonds. These are typically prepared in water, and are surprisingly robust (including to extended heating in polar organic solvents and water). Working with Christian Doonan and colleagues at the University of Adelaide, we have demonstrated that these frameworks can be used to encapsulate and stabilise enzymes. Working with Jonathan Foster at the University of Sheffield, we have shown that 2D hydrogen bonded systems can be exfoliated into single layer nanosheets.

Initial framework: Chem. Sci. 2017, 3019
General synthesis of family of frameworks: Chem. Eur. J. 2019, 10006
Enzyme encapsulation: J. Am. Chem. Soc. 2019, 14298
Hydrogen bonded nanosheets: Chem. Sci. 2021, 3322
Mechanisms of water sorption and structural rearrangements: Chem. Eur. J. 2022, e202201929, Angew. Chem. Int. Ed. 2023, e202212962

Cages:
We are interested in the synthesis of organic cage molecules, either using covalent organic chemistry (both reversible and irreversible), or using supramolecular interactions such as hydrogen bonding. We have recently developed a family of robust organic cages that can be prepared in high yields. Some of these are permanently porous and adsorb gases such as carbon dioxide, while others are potent anion receptors that can function in water. We are also interested in using these cages as building blocks for supramolecular self-assembly and crystal engineering.

Crystal engineering of small covalent cages: Cryst. Growth Des. 2019, 4121
Post-synthetic metallation of porous organic cages: Chem. Eur. J. 2022, e2022
Robust hydrazone cages for selective anion recognition in water: Chemrxiv

Antielectrostatic hydrogen bonds (AEHBs):
Even though they “should” Coulombically repel one another, it is known that under certain circumstances anions can hydrogen bond to one another to form dimers, oligomers and polymers. We initially surveyed the Cambridge Structural Database and showed that these interactions were very common, e.g. more than half of all crystallised bicarbonate anions exist as AEHB dimers. We have used these interactions to assembled 3D hydrogen bonded frameworks in water, and in 2020 wrote the first review of this area in collaboration with Amar Flood’s group at the University of Indiana.

Survey of known AEHBs: CrystEngComm, 2019, 4855
3D framework assembled by AEHBs: Chem. Commun. 2019, 12020
Review of AEHBs: Chem. Soc. Rev. 2020, 7893

Supramolecular chemistry fundamentals:
We are really interested in fundamental (blue skies) studies of supramolecular chemistry, i.e. how trying to uncover how supramolecular chemistry works. We frequently collaborate with computational chemists on this. Recent studies in this area have involved trying to understand amidinium···carboxylate self-assembly in solution, looking at very strong O–H hydrogen bond donors for anion recognition, and investigating the hydrolysis of amidinium and amidine groups in basic water.

Amidinium···carboxylate self-assembly: Chem. Asian J. 2017, 1587
O–H···anion interactions: Chem. Asian J. 2019, 1271; Org. Biomol. Chem. 2021, 2794, Chem. Eur. J. 2022, e202200389
Review of O–H···anion interactions: Chem. Soc. Rev. 2019, 2596
Hydrolysis of amidiniums: J. Org. Chem. 2021, 13762