Frustrated Lewis Pairs
Frustrated Lewis Pairs (FLPs) are infamous in inorganic chemistry for showing unique reactivity towards small molecules, which can be applied to hydrogenation reactions and small molecule activation. Its reactivity is dictated by the unquenched Lewis acid and base centers, which bear large bulky groups that prevent them combining together. Our team has developed the first polymeric version of frustrated Lewis pairs. Our research involves the design, synthesis and polymerization of novel sterically hindered Lewis acid/base-containing monomers. By carefully modifying the substituents around the Lewis base and acid centers, we can tune the reactivity of the resultant polymeric FLPs. Our initial efforts show the transformation of our poly(FLPs) from a solution to a gel, triggered by the addition of a suitable small molecule. This gives rise to a heat-responsive material that can self-heal.
Wang, M.; Nudelman, F.; Matthes, R.; Shaver, M. P. “Frustrated Lewis Pair Polymers as Responsive Self-Healing Gels” J. Am. Chem. Soc. 2017, 139 (40), 14232
Controlled Radical Polymerisation
Our research group works at the interface between catalyst design and polymer synthesis, with a particular interest in atom transfer radical polymerisation (ATRP) and organometallic mediated radical polymerisation (OMRP). We seek to replace toxic or unsustainable mediators of polymerisations with more benign alternatives. Our group has developed first row complexes for the controlled radical polymerisation (CRP) of vinyl monomers. Of particular interest is a family of Fe complexes, which operate via a unique dual-control mechanism to give dispersities as low as 1.1. The polymerisation is now extremely well-understood, with detailed kinetic studies used to understand the mechanism of control and the relative rates of propagation and termination reactions.
Coward, D.; Lake, B.; Shaver, M. P. “Understanding Organometallic-Mediated Radical Polymerization with an Iron(II) Amine–Bis(phenolate)” ACS Organometallics, 2017, 26 (17), 3322
The Versatility of Radical Chemistry
We look into exploiting polymerisation technology in small molecule catalysis. This means looking at ways radical formation is initiated by iron and other earth abundant metals and how it may be harnessed to find new reactivity.
Earth Abundant Initiators
The project involves the synthesis and characterisation of novel anilido-aldimine and half salen complexes with earth-abundant metals. Their catalytic activity in the reverse atom transfer radical polymerisation of styrene and methyl methacrylate will be investigated. Furthermore, they are tested to form in situ catalysts for the ring opening polymerisation of lactide. As the ligands scaffolds are modular, the steric and electronic properties of substituents can be tuned to provide a better control over the polymerisations.