Selective inclusion and separation of cinnamaldehyde and benzaldehyde by insoluble β-cyclodextrin polymer

A novel selective separation method for cinnamaldehyde and benzaldehyde has been developed using insoluble β-cyclodextrin polymer as a host and cinnamaldehyde and benzaldehyde as model guests. The insoluble β-cyclodextrin polymer could form inclusion complex with cinnamaldehyde and benzaldehyde in solid state, so as to selectively separate benzaldehyde and cinnamaldehyde. The inclusion equilibrium constants for cinnamaldehyde and benzaldehyde over the β-cyclodextrin polymer have been calculated through their solid UV–vis spectra, and the binding energies between β-cyclodextrin polymer and the two substrates complexes have been calculated with ONIOM2(B3LYP/6-31G(d):PM3) and semi-continuum solvation model. The driving force of the separation between cinnamaldehyde and benzaldehyde is through the different weak interaction with β-cyclodextrin polymer, i.e., hydrogen bond interaction, which is evidenced by the different binding energies and different inclusion equilibrium constants.

Graphical abstractSelective separation attained by the structures with different binding energies for the β-CDP guest complexes.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Novel selective method was used to separate cinnamaldehyde and benzaldehyde using insoluble β-cyclodextrin polymer. ► The difference of binding energies obtained by ONIOM is an important characteristic for separation of the mixtures. ► Separation factor k is why we could selectively separate cinnamaldehyde from benzaldehyde.