title: Vibrational and electronic circular dichroism of dimethyl mesobilirubins-XIIIα.
abstract: The vibrational circular dichroism (VCD) spectra of (αR,α'R)-, (αS,α'S)-, (βR,β'R)-, and (βS,β'S)-dimethylmesobilirubin-XIIIα have been recorded in the range of 1800-900 cm(-1) in CDCl3 solution and in mixed DMSO-d6/CDCl3 solutions. Ab initio density functional theory (DFT) calculations predict IR vibrational absorption (VA) and VCD spectra in excellent to good correspondence with observed data. The same calculations confirmed the ridge-tile conformation that has been known for a long time. Assignment of vibrational normal modes (NMs) sheds light on the relative importance of local moieties and groups in determining conformational properties of the molecules, as well as their interaction with solvent molecules. Time-dependent DFT (TDDFT) calculations were also performed to provide an understanding of electronic circular dichroism (ECD) spectra and confirm the well-known interpretation based on the exciton model.
authors.affiliation: Dipartimento di Scienze Biomediche e Biotecnologie, Università di Brescia , 25123 Brescia, Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Abbate
authors.forename: France
authors.initials: F
authors.lastname: Lebon
authors.forename: Giovanna
authors.initials: G
authors.lastname: Longhi
authors.forename: Stefan E
authors.initials: SE
authors.lastname: Boiadjiev
authors.forename: David A
authors.initials: DA
authors.lastname: Lightner
mesh_terms: D001663:Bilirubin / Q000737:chemistry*; D002942:Circular Dichroism; D004581:Electronics; D006860:Hydrogen Bonding; D007259:Infrared Rays; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D012996:Solutions; D012997:Solvents / Q000737:chemistry; D013997:Time Factors; D014732:Vibration
chemical_list: D012996:Solutions; D012997:Solvents; D001663:Bilirubin