Our aim is to explore the organisation of complex molecules on surfaces with the aim of understanding how large scale structures are determined by local intermolecular interactions such as hydrogen bonding, halogen bonding and metal-co-ordination.
These studies include the spontaneous formation of open nanoporous molecular networks which can be used as nanoscale containers to capture other materials and control growth on a surface. In addition we have recently identified an arrangement stabilised by hydrogen bonding where entropy plays a significant role and we are planning future studies to extend this approach to other disordered molecular tilings to investigate exotic two-dimensional phases and quasi-crystalline ordering. Collaborations with Nottingham chemists (Champness) form an important part of this activity.
The packing of macromolecules on surfaces has emerged as an important current theme and these materials display novel structural properties due to the competition of their interactions and internal elastic deformation. These studies have included linear porphyrin polymers with interesting optoelectronic applications and we are now focussing on analogue nanorings – cyclic structures formed as closed loop polymers. This worked is performed in collaboration with chemists at Oxford (Anderson).
The growth of one- and two-dimensional polymers on surface is being investigated in the group as a route to form graphene analogue materials. Several coupling reactions are being investigated as routes to extended two-dimensional networks which have a high degree of connectivity across macroscopic areas. We have also developed methods to release these films from the substrates on which they are formed using a molecular adhesive (based on fullerene thin films) and are now exploring the optical and electronic properties of the resulting materials.
We are also developing techniques to fabricate double layer graphene devices in which a thin layer of material is sandwiched between two graphene electrodes. The ‘sandwich’ layer is chosen to be insulating and must be very thin, down to a few nanometres. We are currently exploring organic materials for tunnel barriers, biomolecular nanosheets for dielectrics, colloidal quantum dots, layered optical emissive materials and metal-organic frameworks (see below).
Metal-organic frameworks are ordered crystalline materials in which organic molecules (often linear) form connections through metal ions. This results in a material in which molecular rods are connected by metal ions to form a highly open porous structure. These materials are of great interest for the capture and storage of gases as well as sensors and for catalysis. In collaboration with Nottingham chemists Champness and Schroder we have started a new programme to grow this films of metal organic frameworks which is aimed both at technological applications and a fundamental study of the initial phases of growth.
We would be very interested to hear from prospective PhD students who are interested in the following projects:
- Adsorption, packing and optoelectronics of porphyrin polymers and nanorings.
- Graphene multilayer devices for transistors and sensors.
- Growth and electronic properties of metal-organic frameworks.
- Exotic phases and quasicrystalline ordering in two-dimensional molecular tiling.
- The formation of two-dimensional polymers and grapheme analogues.