Research Guides

Department of Chemistry University of Oxford

Professor H.L. Anderson FRS

Current Research Projects — Molecular Engineering

We design and synthesise new molecular materials, and explore how their properties relate to their molecular structures. This is "molecular engineering" – engineering at the nano-scale. We use non-covalent self-assembly to control the behaviour of organic semiconductors and dyes, for diverse applications. Our core technique is synthesis, but we also do many other types of experiments, from biological testing to solid-state physics. We explore the conformational, electronic and recognition properties of our compounds using a wide range of spectroscopic and analytical techniques, and we collaborate closely with physicists, physical chemists and biologists.

Projects are being pursued in the following areas: (1) Light-harvesting π-conjugated porphyrin arrays; (2) Photoactive molecules as tools for biomedical research; (3) Single-molecule electronic devices; (4) Polyyne rotaxanes and catenanes; (5) Understanding cooperatively and molecular recognition; (6) Luminescent insulated molecular wires.

1. Light-Harvesting π-Conjugated Arrays

We have developed the template-directed synthesis of nanorings consisting of up to 50 porphyrin units. These are ideal systems for exploring quantum-coherent energy delocalisation and charge circulation. Current targets include nanotubes and fullerene-like domes. [Key refs: J. Am. Chem. Soc. 2015, 137, 12713; Angew. Chem. Int. Ed. 2015, 54, 7344; Nature Chem. 2015, 7, 317; Angew. Chem. Int. Ed. 2015, 54, 5355; Chem. Sci. 2015, 6, 181; Nature 2011, 469, 72]
Collaborators: Laura Herz and Robin Nicholas (Oxford Physics), Chris Timmel and Tim Claridge (Oxford Chemistry), Peter Beton (Nottingham Physics), Aleks Rebane and Mikhail Drobizhev (Montana, USA), Bo Albinsson (Göteborg, Sweden), Donatas Zigmantas (Lund, Sweden), Steve Meech and Ismael Heisler (University of East Anglia).
[12-porphyrin nanotube and its HOMO distribution]

2. Photoactive Molecules as Tools for Biomedical Research

Optical excitation is an excellent approach to probing live cells, and to intervening in their chemistry, particularly when mediated by purpose-built photoactive molecules. We are working on several projects in this area including (a) switchable dyes for super-resolution microscopy, (b) optical probes for monitoring membrane potential in cells such as neurons, and (c) photo-activated drugs. [Key refs: Chem. Sci. 2015, 6, 2419; Nat. Neurosci. 2014, 17, 383; Angew. Chem. Int. Ed. 2013, 52, 9044; Biophys. J. 2012, 103, 907Phys. Chem. Chem. Phys. 2010, 12, 13484]
Collaborators: Christian Eggeling (Oxford Weatherall Institute for Molecular Medicine), Ilan Davis (Oxford Biochemistry), Marina Kuminova (Imperial, London), Peter Ogilby (Aarhus, Denmark), Koen Clays (Leuven, Belgium), Mireille Blanchard-Desce (Bordeaux).
[Voltage-sensitive dyes in lipid bilayer membranes exhibit second harmonic generation and detect electric field]

3. Single-Molecule Electronic Devices

Many new techniques have been developed recently for measuring the conductance of single molecules. We are exploring the design of molecular wires and transistors that can exploit the unique behaviour of single molecules, such as quantum interference.  Current work involves contacting molecules to electrodes made from gold and graphene. [Key refs: Nanoscale 2015, 7, 13181; Adv. Mater. 2012, 24, 653Nature Nanotech.20116, 517]
Collaborators: Andrew Briggs, Lapo Bogani and Jan Mol (Oxford Materials),  Richard Nichols, Simon Higgins and Andrew Hodgson (Liverpool Chemistry), Colin Lambert (Lancaster Physics), Brendon Lovett (St Andrews).
[Calculated structures of a porphyrin trimer connected to gold electrodes]

4. Polyyne Rotaxanes and Catenanes

Rotaxane formation can provide a way to stabilise long polyynes. We are pursing strategies for creating new molecular allotropes of sp1 carbon. [Key refs: J. Am. Chem. Soc. 2014, 136, 17996; Org. Lett. 2012, 14, 3424; Chem. Sci. 2011, 2, 1897]
Collaborators: Rik Tykwinski (Erlangen, Germany), Tony Parker (Central Laser Facility, Rutherford Appleton Laboratory), Amber Thompson (Oxford Chemistry).
[A polyyne rotaxane and its rhenium(I) complex]

5. Understanding Cooperativity and Self-Assembly

The factors controlling cooperativity in multi-valent molecular recognition are still not well understood. We are studying the thermodynamic stabilities of families of multivalent complexes, using UV-vis-NIR and NMR spectroscopy, and organic synthesis. [Key refs: J. Am. Chem. Soc. 2015137, 12713;  Angew. Chem. Int. Ed. 201554, 7344; Nature Chem. 20157, 317; Angew. Chem. Int. Ed. 2009, 48, 7488]
Collaborators: Chris Hunter (Cambridge), Tim Claridge (Oxford Chemistry).
[1:12 double-strand complex of a porphyrin nanoring and its denaturation with excess DABCO]

6. Luminescent Insulated Molecular Wires — Rotaxanes & Polyrotaxanes

We are investigating insulated molecular wires which consist of conjugated polymers threaded through cylindrical insulating macrocycles. Insulation enhances the stability and luminescence of the molecular wire while preserving its semiconductivity. [Key refs: J. Phys. Chem. C 2014, 118, 4553; Adv. Mater. 2013, 25, 4347; Small 2013, 9, 2619]
Collaborators: Franco Cacialli (UCL, London), Paolo Samori (Strasbourg, France), Guglielmo Lanzani (Milan, Italy), Ivan Scheblykin (Lund, Sweden), Frank Würthner (Würzburg, Germany).
[Model of an insulated molecular wire; β-cyclodextrin rings shown in green]