1. School of Biological & Chemical Sciences, Queen Mary, University of London, Walter Basent Building, Mile End Road, London E1 4NS, U.K.
2. ISIS neutron facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 0QX, U.K.
3. Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland