Supporting Information. PDF containing information on: synthesis (Section 1) and crystallography (Section 2) of the FSPA solvates; C NMR (Section 3); explanation and justification of parameters used to fit 2 H relaxation data (Section 4); Details of 2 H NMR, naïve modelling and details of direct prediction (Section 5); additional analysis of MD results, including analysis of the sulfonamide behavior (Section 6); further details of the Markov State Modelling (Section 7). This material is available of charge via the Internet at .