Gas-phase fragmentation of host-guest complexes between β-cyclodextrin and small molecules.

Noncovalent interactions are ubiquitous in molecular interaction and supramolecular self-assembly. As a model system, host-guest complexes between β-cyclodextrin (β-CD) and small molecules have been extensively studied and widely used in a variety of application fields including drug transportation and fluorescence enhancement. However, details on how guest molecules interact with the β-CD hosts to demonstrate the observed effects still remain to be further studied. In this work, we report the study of gas-phase fragmentation of host-guest complexes formed between β-CD and small guest molecules by using collision induced dissociation (CID). The CID mass spectra of the complexes changed dramatically as the collision energy was increased. Fragmentation patterns of β-CD complexed with different small molecules were analyzed and the differences in the presence/absence of fragment ions from the β-CD were attributed to varied proton affinity of the small molecules. Furthermore, the CE(50) values fitted from the fragmentation curves were used in the qualitative evaluation of interactions in noncovalent host-guest systems.