title: Electronic and vibrational circular dichroism spectra of chiral 4-X-[2.2]paracyclophanes with X containing fluorine atoms.
abstract: The absorption IR and vibrational circular dichroism (VCD) spectra of both enantiomers of 4-X-[2.2]paracyclophanes (X = F, CH(2)F, COCF(3)) have been recorded in the mid-IR and CH stretching regions. The electronic CD (ECD) spectra have been collected as well. VCD spectra in the two IR regions, 900-1700 cm(-1) and 2700-3200 cm(-1), have been compared with the corresponding DFT calculated spectra. The absolute configuration assignment was confirmed as previously determined. We have shown that, to various extents, the VCD and ECD spectra bear some information on the relative mobility of the two phenyl rings and on the existence of different conformers for the X group. It has been observed that X = F and X = CH(2)F groups do not change the conformational and electronic properties of the parent X = H and X = CH(3) molecules. The X = COCF(3) group brings in a large perturbation to the [2.2]paracyclophanes, and the role of fluorine is less important than that of oxygen.
authors.affiliation: Dipartimento di Scienze Biomediche e Biotecnologie, Università di Brescia, Viale Europa 11, 25123 Brescia, Italy. abbate@med.unibs.it
authors.forename: Sergio
authors.initials: S
authors.lastname: Abbate
authors.forename: France
authors.initials: F
authors.lastname: Lebon
authors.forename: Roberto
authors.initials: R
authors.lastname: Gangemi
authors.forename: Giovanna
authors.initials: G
authors.lastname: Longhi
authors.forename: Sara
authors.initials: S
authors.lastname: Spizzichino
authors.forename: Renzo
authors.initials: R
authors.lastname: Ruzziconi
mesh_terms: D002942:Circular Dichroism; D004583:Electrons; D005461:Fluorine / Q000737:chemistry*; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry*; D011789:Quantum Theory; D013237:Stereoisomerism; D014732:Vibration
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D005461:Fluorine