title: Theoretical study of the geometrical and electronic structures and thermochemistry of spherophanes.
abstract: A set of supramolecular cage-structures--spherophanes--was studied at the density functional B3LYP level. Full geometrical structure optimisations were made with 6-31G and 6-31G(d) basis sets followed by frequency calculations, and electronic energies were evaluated at B3LYP/6-31++G(d,p). Three different symmetries were considered: C1, Ci, and Oh. It was found that the bonds between the benzene rings are very long to allow pi-electron delocalisation between them. These spherophanes show portal openings of 2.596 A in Spher1, 4.000 A in Meth2, 3.659 A in Oxa3, and 4.412 A in Thia4. From the point of view of potential host-guest interaction studies, it should also be noted that the atoms nearest to the centre of the cavities are carbons bonded to X groups. These supramolecules seem to exhibit relatively large gap HOMO-LUMO: 2.89 eV(Spher1), 5.26 eV(Meth2), 5.73 eV(Oxa3), and 4.82 eV(Thia4). The calculated Delta H degrees (f) (298.15 K) values at B3LYP/6-31G(d) are (in kcal mol(-1)) 750.98, 229.78, -10.97, and 482.49 for Spher1, Meth2, Oxa3, and Thia4, respectively. Using homodesmotic reactions, relative to Spher1, the spherophanes Meth2, Oxa3, and Thia4 are less strained by -399.13 kcal mol(-1), -390.40 kcal mol(-1), and -411.38 kcal mol(-1), respectively. Their infrared and (13)C NMR calculated spectra are reported.
authors.affiliation: Department of Chemistry, University of Fribourg, Fribourg, Switzerland.
authors.forename: Amar
authors.initials: A
authors.lastname: Saal
authors.forename: Claude August
authors.initials: CA
authors.lastname: Daul
authors.forename: Thibaut
authors.initials: T
authors.lastname: Jarrosson
authors.forename: Ourida
authors.initials: O
authors.lastname: Ouamerali
mesh_terms: D004583:Electrons; D008697:Methane / Q000737:chemistry*; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry*; D013455:Sulfur / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics
chemical_list: D013455:Sulfur; D008697:Methane; D010100:Oxygen