Expanding capsules

Abstract

A self-assembled capsule held together by hydrogen bonding incorporates spacer modules that extend the capsule's length and increase its capacity. The modules are glycoluril derivatives that provide appropriate molecular curvature and complementary hydrogen bonding surfaces. Four glycoluril modules insert into the capsule in a chiral arrangement and allow encapsulation of longer guests. Specifically, n-tetradecane is the longest guest accommodated by the original capsule, but normal alkanes C15–C19 fit into the extended capsule. The hydrogen bonded, dimeric capsule can be expanded with 4, 8 or 12 glycoluril spacers that increase the cavity's volume by up to 530 Å3 and length by ∼21 Å. The extended assemblies are chiral and encapsulate a variety of longer normal alkanes. A large variety of molecular capsules can be created from just a small collection of building blocks. A hydrogen-bonded, dimeric capsule can be expanded with 4, 8 and 12 glycoluril spacers that increase the cavity's volume by up to 530 A˚3 and length by∼21 A˚.