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 CE50 values fitted from the fragmentation curves were used in the qualitative evaluation of interactions in noncovalent host–guest systems.