title: Synchrotron radiation linear dichroism (SRLD) investigation of the electronic transitions of quinizarin, chrysazin, and anthrarufin.
abstract: The electronic transitions of the three alpha,alpha'-dihydroxy derivatives of anthraquinone, 1,4-dihydroxy-, 1,8-dihydroxy-, and 1,5-dihydroxy-9,10-anthraquinone (quinizarin, chrysazin, and anthrarufin), were investigated by synchrotron radiation linear dichroism (SRLD) spectroscopy on samples aligned in stretched polyethylene. With synchrotron radiation, polarization data could be determined in the UV region up to ca. 58,000 cm(-1) (7.2 eV), which amounts to an extension by ca. 11,000 cm(-1) (1.4 eV) relative to the range accessible with a conventional light source. Throughout the investigated region (15,000-58,000 cm(-1)), essentially similar wavenumbers, intensities, and transition moment directions were determined for chrysazin and anthrarufin, while the spectrum of quinizarin deviated significantly. The results of time-dependent density functional theory (TD-DFT) calculations were in good agreement with the experimental spectra, leading to the assignment of 10 electronic states for quinizarin, and 8 electronic states for chrysazin and anthrarufin. No evidence was found for contributions from different tautomeric or rotameric forms to the observed spectra.
authors.affiliation: Department of Science, Systems and Models, Roskilde University, Universitetsvej 1, Bldg. 18, DK-4000 Roskilde, Denmark.
authors.forename: Duy Duc
authors.initials: DD
authors.lastname: Nguyen
authors.forename: Nykola C
authors.initials: NC
authors.lastname: Jones
authors.forename: Søren Vrønning
authors.initials: SV
authors.lastname: Hoffmann
authors.forename: Jens
authors.initials: J
authors.lastname: Spanget-Larsen
mesh_terms: D000880:Anthraquinones / Q000737:chemistry*; D004583:Electrons; D008958:Models, Molecular; D013057:Spectrum Analysis / Q000379:methods*; D013237:Stereoisomerism; D017356:Synchrotrons
chemical_list: D000880:Anthraquinones; C034890:1,4-dihydroxyanthraquinone; C004315:danthron