A combined experimental and theoretical study on the conformational behavior of a calix[6]arene
Résumé
An experimental and theoretical study on the conformational behavior of the 1,3,5-OMe-2,4,6-OCH2CONHOH-p-tert-butylcalix[6]arene has been carried out. In particular, semiempirical (AM1) and density functional theory (DFT) calculations have been performed in order to identify the possible conformers. The obtained results show that the cone structure is the most stable conformer at any level of theory, even if significant differences have been obtained for the other species. The inclusion of solvent effect, through a continuum model, also points out the relevant role played by the solvent in the stabilization of the cone structure in solution. These latter results have been confirmed by NMR experiments, which clearly show the presence of only the cone conformer in a polar solvent, such as DMSO. Finally, 1H and 13C NMR spectra on model systems, i.e., two successive phenol rings (Ar1-CH2-Ar2), have been computed at the DFT level and compared with the experimental spectra of the complete molecule. The results show an overall good agreement with the experimental data, thus leading to an unambiguous assignment of the experimental spectra. © 2006 American Chemical Society.
Mots clés
Conformations
Mathematical models
Molecular structure
Nuclear magnetic resonance
Probability density function
Solvents
Cone structure
Continuum model
Density functional theory (DFT)
Solvent effect
Olefins
calixarene
article
chemical model
chemical structure
chemistry
computer simulation
conformation
methodology
nuclear magnetic resonance spectroscopy
sensitivity and specificity
Calixarenes
Computer Simulation
Magnetic Resonance Spectroscopy
Models
Chemical
Molecular
Molecular Conformation
Sensitivity and Specificity