1. Chemistry Department, University of Coimbra, 3004-535 Coimbra, Portugal, Physical Chemistry 1, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden, Centro de Investigação em Química, Chemistry Department, University of Porto, 4169-007 Porto, Portugal, and Camurus AB, Ideon Science Park, SE-223 70 Lund, Sweden