Department of Chemsitry

Professor H.L. Anderson FRS

Organic Chemistry

harry.anderson@chem.ox.ac.uk

Telephone: 44 (0) 1865 275704
 
 

 

Research

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 main 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 with many groups of physicists, physical chemists and cell biologists.

1. Template-Directed Synthesis of Nanorings
Belt-like nanorings consisting of 6, 8, 12  or more porphyrin units are prepared using radial oligo-pyridine templates. These nanorings are ideal systems for exploring quantum-coherent energy delocalisation and charge circulation. New synthetic strategies such as ‘Vernier templating’ will provide access to even larger nanorings. [Key refs: J. Am. Chem. Soc.2011, 133, 17262; Chem. Sci.2011, 2, 1897; Nature2011, 469, 72; J. Am. Chem. Soc.2008, 130, 10171; Angew. Chem. Int. Ed.2007, 46, 3122]
Collaborators: Laura Herz (Oxford Physics), Jeff HarmerChris Timmel and Philipp Kukura (Oxford Chemistry), Peter Beton (Nottingham Physics), David Beljonne (Mons Theory, Belgium).
 
 
[Left: X-ray structure of 6-porphyrin nanoring; Right: STM image of 12-porphyrin nanoring]
 
2. Drugs for Photodynamic Therapy
Photodynamic therapy (PDT) is a technique for killing diseased cells using the excited state of a dye (see here for information on PDT). We are developing porphyrin-based drugs for PDT via two-photon excitation. Recently we achieve the first demonstration of two-photon excited PDT in a living mammal and showed that the technique can be used to close blood vessels with pin-point spatial selectivity. [Key refs: J. Am. Chem. Soc.2009, 131, 7948; Nature Chem.2009, 1, 69; Org. Biomol. Chem.2009, 7, 874; Org. Biomol. Chem.2009, 7, 897; Nature Photonics2008, 2, 420; Photochem. Photobiol.2007, 83, 1441]
Collaborators: Brian Wilson (Toronto), Marina Kuminova (Imperial, London), Peter Ogilby (Aarhus, Denmark).
 
     
[Human cancer cells strained with the porphyrin drug prototype "Oxdime", developed in Oxford]
 
3. Insulated Molecular Wires - 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. [Adv. Mater.2011, 23, 1855; Adv. Mater.2010, 22, 3690; Adv. Funct. Mater.2010, 20, 272; J. Appl. Phys.2010, 107, 124509; Appl. Phys. Lett.2009, 95, 31108; NanoLett.2008, 8, 4546; Adv. Mater.2008, 20, 3218; J. Am. Chem. Soc.2007, 129, 12384; Angew. Chem. Int. Ed.2007, 46, 1028]
Collaborators: Franco Cacialli (UCL, London), Paolo Samori (Strasbourg, France), Guglielmo Lanzani (Milan Physics, Italy).
 
[Model of an insulated molecular wire; β-cyclodextrin rings shown in green]
 
4. Porphyrin-Based Molecular Wires
We use porphyrins to create molecular wires, and explore their properties. Charge-transport through porphyrin oligomers, connected to gold metal contacts, takes place by a phase-coherent tunnelling mechanism, and exhibits an amazingly shallow distance-dependence. [Key refs: Nature Nanotech.2011, 6, 517; J. Am. Chem. Soc.2011, 133, 9863; Small2010, 6, 2604; J. Am. Chem. Soc.2009, 131, 5522; J. Am. Chem. Soc.2008, 130, 8582; J. Am. Chem. Soc.2007, 129, 13370;J. Am. Chem. Soc.2007, 129, 4291]
Collaborators: Richard Nichols (Liverpool Chemistry), Emyr Macdonald (Cardiff Physics), Bo Albinsson (Chalmers, Sweden), Laurens Siebbeles (Delft, The Netherlands), Colin Lambert (Lancaster Physics).
 
[Calculated structures of a porphyrin trimer connected to gold electrodes]
 
5. Probes for Cell Membranes
The ability to image electrical impulses in neurons and cardiac cells will lead to better understanding of brain and muscle function. We are developing a range of voltage-sensitive dyes. Amphiphilic porphyrins exhibit strong second-harmonic generation in biological plasma membranes, and may be valuable for imaging potential. We are also exploring other imaging strategies. [Key refs: Phys. Chem. Chem. Phys.2010, 12, 13484; J. Am. Chem. Soc.2009, 131, 2758]
Collaborators: Ole Paulsen (Cambridge Neuroscience), Koen Clays (Leuven Chemistry, Belgium), Tony Wilson (Oxford Engineering), Hagan Bayley and William Barford (Oxford Chemistry).
 
[SHG images of a cell and a water-in-oil droplet protocell model, water]
 
6. Supramolecular Chemistry of Carbon Nanotubes
Single walled carbon nanotubes bind strongly to porphyrin oligomers to give materials that may be useful in photovoltaic devices. [Key refs: Angew. Chem. Int. Ed.2011, 50, 2313; ACS Nano2011, 5, 2307]
Collaborators: Robin Nicholas and Laura Herz (Oxford Physics).
 
[UV-vis titration showing binding of a porphyrin tetramer to carbon nanotubes]
 
7. Near-IR Nonlinear Optical Dyes
Delocalised carbocations exhibit strong nonlinear optical behaviour at telecommunications wavelengths. “Molecular graphenes” have been synthesised which exhibit remarkable redox activity and near-IR absorption, and have potential as discotic charge-transport materials. The group has also investigated dyes derived from perylene bisimides and squaraine-linked porphyrins, as materials with potential for all-optical signal processing. [J. Am. Chem. Soc.2011, 133, 30; J. Am. Chem. Soc.2009, 131, 7510; J. Am. Chem. Soc.2009, 131, 6099; Angew. Chem. Int. Ed.2008, 47, 7095]
Collaborators: Joseph Perry, Seth Marder and Jean-Luc Bredas (Georgia Tech USA), AleksRebane and Mikhail Drobizhev (Montana, USA).
 
 
[A tetra-anthracene porphyrin exhibiting string absorption in the near-IR]
 
8. Cooperative Self-Assembly
Studies of thermodynamic equilibria are generating greater understanding of cooperativity in multivalent self-assembly processes. [Key refs: J. Am. Chem. Soc.2011, 133, 20962; Angew. Chem. Int. Ed.2011, 50, 5572; Angew. Chem. Int. Ed.2009, 48, 7488]
 
[A 14-component complex formed in a cooperative all-or-nothing self-assembly process]
 
9. Quantum Entanglement and Quantum Information Processing
We are investigating the synthesis and spectroscopy of systems with several coupled paramagnetic centres and/or nuclear spins, to explore the scope for molecular quantum information processing. [Key refs: Phys. Rev. Lett.2010, 104, 200501; Org. Lett.2010, 12, 3544; J. Am. Chem. Soc.2009, 131, 13852]
Collaborators: John Morton and Andrew Briggs (Oxford Materials).

10. Materials for Photovoltaic Solar Cells
We are developing new chromophores for dye-sensitsised solar cells, for harvesting solar power.
Collaborators: Henry Snaith and Laura Herz (Oxford Physics).

11. Light-Activated Drugs
Photo-labile protecting groups enable a physiologically active compound to be "un-caged" inside living cells with high spatial and temporal resolution. We are developing new one- and two-photon activated caging groups. [Key refs: J. Neuroscience2011, 31, 8564Angew. Chem. Int. Ed.2009, 48, 3244]
Collaborators: Ole Paulsen (Cambridge Neuroscience), MireilleBlanchard-Desce (Bordeaux).

12. Polymer Adjuvants
Adjuvants are compounds which stimulate the immune system and increase the response to vaccines, without having an intrinsic antigenic effect. We are investigating multivalent polymer-TLR ligands which are designed to activate a cytokine response.
Collaborators: Leonard Seymour (Oxford Clinical Pharmacology).


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