The MSM analysis of the ethanol solvates shows that the ethanol motion is complex, with a higher degree of librational character; only 76% of the variance is captured by the first two TICs. There are two distinct macrostates in the free energy plot, Figure (b) separated by a 180° rotational flip, as shown in Figure . Each of these states contains three sub-states corresponding to rotation about the molecular long axis, with H-bonding occurring in each case between the ethanol hydroxyl group and oxygen Hbond donors of FSPA. See Section 7 of the Supplementary Information for more detailed quantitative analysis of the motion.