A research team at the University of Manchester has shown that by tuning the surface properties of graphene, it is possible to change the type of polymorphs produced. Glycine, the simplest amino acid, has been used as reference molecule, while different types of graphene have been used either as additive or as templates.

Matthew Boyes and Adriana Alieva, PhD students at The University of Manchester, both contributed to this work: “This is a pioneering work on the use of graphene as an additive in crystallization experiments. We have used different types of graphene with varying oxygen content and looked at their effects on the crystal outcome of glycine. We have observed that by carefully tuning the oxygen content of graphene, it is possible to induce preferential crystallisation”, said Adriana.

Computer modelling, performed by Professor Melle Franco at the University of Aveiro, Portugal, supports the experimental results and attributes the polymorph selectivity to the presence of hydroxyl groups allowing for hydrogen bonding interactions with the glycine molecules, thereby favouring one polymorph over the other, once additional layers of the polymorph are added during crystal growth.