1. Department of Physics, University of Warwick, Coventry CV4 7AL, U.K.
2. Department of Chemistry, Imperial College London, London SW7 2AZ, U.K.
3. Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K.
4. GSK R&D, Stevenage, Hertfordshire SG1 2NY, U.K.
5. GSK R&D, Collegeville, Pennsylvania 19426, United States