title: Induced circular dichroism and structural assignment of the cyclodextrin inclusion complexes of bicyclic azoalkanes.
abstract: The stoichiometries and binding constants of the host-guest complexes between the bicyclic azoalkanes 1-6 and alpha-, beta-, and gamma-cyclodextrins (CDs) and the induced circular dichroism (ICD) of the complexes were analyzed. Assisted by proximity relationships obtained from 2D ROESY NMR spectra, the signs and intensities of the ICD spectra are interpreted in terms of the solution structures (co-conformations) of the CD complexes. The ICD assignments are based on the orientation-intensity ICD rules of Harata and Kodaka, which relate the ICD signs and intensities to the relative orientation of the electric dipole transition moment of the n,pi azo chromophore to the CD axis. The influence of the size of the guest and the host is discussed and the effect of introducing an additional chromophore (either a phenyl or a second azo group) on the ICD spectra is demonstrated.
authors.affiliation: School of Engineering and Science, International University Bremen, Campus Ring 1, 28759 Bremen, Germany.
authors.forename: Hüseyin
authors.initials: H
authors.lastname: Bakirci
authors.forename: Xiangyang
authors.initials: X
authors.lastname: Zhang
authors.forename: Werner M
authors.initials: WM
authors.lastname: Nau
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry*; D002942:Circular Dichroism; D003505:Cyclodextrins / Q000737:chemistry*; D005470:Fluorometry; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D001391:Azo Compounds; D019086:Bridged Bicyclo Compounds, Heterocyclic; D003505:Cyclodextrins