betadex and nonanal

Semiempirical calculations on cyclomaltoheptaose (beta CD), 1,7-dioxaspiro[5.5]undecane (1), nonanal (2), and the inclusion complexes of beta CD with 1 and 2 were carried out using the AM1 method. The structure of beta CD after complete geometry optimization was in very good agreement with crystallographic structures. Moreover, the calculated dipole moment of beta CD was found to depend strongly upon the orientation of the primary hydroxyl groups. Different possible positions of the guest molecules in the beta CD cavity were examined, a few of them resulting in a gain of energy. These corresponded to partial inclusion of 1 from the secondary side but total inclusion of 2. Conclusions regarding the geometries of the complexes were in satisfactory agreement with the dominant structures in aqueous solutions as derived from NMR experiments. Thermodynamic data (delta H(O), delta S(O)) in aqueous solutions were obtained from van't Hoff plots using 1H NMR, and were compared with the computed heats of formation. The forces responsible for host-guest association are discussed in the light of the above results.

Topics: Aldehydes; beta-Cyclodextrins; Carbohydrate Conformation; Carbohydrate Sequence; Crystallography, X-Ray; Cyclodextrins; Magnetic Resonance Spectroscopy; Models, Molecular; Molecular Sequence Data; Molecular Structure; Thermodynamics

The inclusion complexes of cyclomaltoheptaose (beta CD) and heptakis(2,3,6-tri-O-methyl)cyclomaltoheptaose (TM-beta CD) with the four major components of the pheromone of the olive fruit fly (Dacus oleae), namely 1,7-dioxaspiro[5.5]undecane, (-)-alpha-pinene, nonanal, and ethyl dodecanoate, and the complex of heptakis(2,6-di-O-methyl)cyclomaltoheptaose (DM-beta CD) with 1,7-dioxaspiro[5.5]undecane were studied. The complexes were characterised in the solid state by differential scanning calorimetry and X-ray powder diffraction. In aqueous solution, the structure of the complexes was investigated by 1H NMR spectroscopy. In solution, 1,7-dioxaspiro[5.5]undecane, (-)-alpha-pinene, and nonanal enter the cavity of the cyclo-oligosaccharides. Association constants for some of these complexes were also measured. The complexes of ethyl dodecanoate did not provide evidence of their structure in solution. This was attributed to the existence of negligible amounts of these complexes in water due to the combined effects of low solubility and low association constant.

Topics: Aldehydes; Alkanes; Animals; beta-Cyclodextrins; Bicyclic Monoterpenes; Calorimetry, Differential Scanning; Cyclodextrins; Diptera; Laurates; Magnetic Resonance Spectroscopy; Monoterpenes; Sex Attractants; Solutions; Terpenes