Probing the stability of multicomponent self-assembled architectures based on cucurbit[8]uril in the gas phase.

Aqueous supramolecular chemistry and highly controlled self-assembly of multi-component architectures are novel tools for investigating and answering questions with different biological implications. Among other self-assembly motifs the barrel-shaped host molecule cucurbit[8]uril (CB[8]) is of particular interest due to its capability of incorporating two guest molecules simultaneously in its hydrophobic cavity. This allows for its use as a supramolecular linking unit to conjugate two different entities such as polymers, peptides, and proteins as well as conjugation of various species to surfaces, colloids and nanoparticles. This study aims to improve our understanding of CB[8] ternary complex formation and stability. A series of CB[8] architectures of different size and chemistry have been analyzed in the gas phase to obtain information about their stability in the absence of solvent effects. While hydrophobic effects and solvation energies play a crucial role for host-guest affinities in solution, gas phase stabilities are determined by the guest's ability to form hydrogen bonding and electrostatic interactions. Increasing the size of the second guest resulted in an increase of gas phase stability, likely due to additional non-covalent interactions.