Cucurbituril-7 (CB[7]) is a macrocyclic host molecule from the cucurbituril family, consisting of seven glycoluril units linked by methylene bridges. It has a hydrophobic, barrel-shaped cavity that can encapsulate guest molecules, forming highly stable host-guest complexes. CB[7] is widely used in supramolecular chemistry, drug delivery, and molecular recognition due to its strong binding affinity and selective interactions.