**Abstract**

Today it is well-established that solvents demonstrate an important role in chemistry. Solvents are able to affect the reactivity, as well as the electronic, optical, and generally physicochemical properties of compounds in solution. Taking this into account, in this chapter we analyze the importance of solvent polarity in phenomena closely related to supramolecular systems as well as the aptitude of various supramolecules to interact with solvent molecules and thus to give rise to chromic effects such as solvatochromism. Main focus is placed on mechanically interlocked molecules, e.g., rotaxanes, catenanes, etc., exhibiting solvent-controlled shuttling movements, switching, and/or solvatochromism. The effect of solvents in various supramolecular architectures is a further focus of this chapter.

**Keywords:** solvents, medium responsiveness, supramolecular recognition, solvatochromism, supramolecules, mechanically interlocked molecules, shuttle movements, supramolecular architectures
