1. Departamento de Química, Universidad de Navarra, 31080 Pamplona, Spain
2. Institut Laue-Langevin, 71 Avenue des Martyrs, B.P. 156, 38042 Grenoble Cedex, France
3. Institute of Pharmaceutical Science, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, SE1 9NH London, U.K.