Is seven the minimum number of water molecules per ion pair for assured biological activity in ionic liquid-water mixtures?

Ionic liquids (ILs) containing small amounts of water are called hydrated ILs and they show diverse physico-chemical properties that are strongly dependent on their water content. Some properties of hydrated ILs, such as biological activity and phase transition behaviour, were found to change non-linearly, with an inflection at a water molecule to ion pair ratio of around 7:1. This critical hydration number of ILs has been discussed in this paper with respect to the state of solvated water molecules.