Studies of the tautomeric forms of alizarin in the ground state by electronic spectroscopy combined with quantum chemical calculations

Environmental and complexation effects on the structures and spectroscopic signatures of organic pigments relevant to cultural heritage: the case of alizarin and alizarin–Mg(ii)/Al(iii) complexes

“…We note that absolute positions of the S 1 ← S 0 transitions for both proton transfer conformers of neutral 1,2NT alizarin are shifted by approximately 50 nm with respect to experiment. This discrepancy can be ascribed to the sensitivity of proton transfer (PT) processes to environmental effects 81,101 , as well as to the effects of the choice of functional. We have tested both effects; Figure 14 shows that from the the computations performed with B3LYP, CAM-B3LYP and ωB97XD, with or without inclusion of few explicit solvent molecules, neither match the position absorption maxima, but all reproduce correctly the band shape.…”

“…Experimental 81 and simulated electronic spectra of the neutral form of free alizarin computed with B3LYP, CAM-B3LYP and ωB97XD functionals and aug-N07D basis set. Simulated VG spectra of 1,2NT(PT1) in methanol solution (CH 3 OH) described by CPCM model and by CPCM plus 3 explicit water molecules in the first solvation shell.…”

Determination of Secondary Species in Solution through Pump-Selective Transient Absorption Spectroscopy and Explicit-Solvent TDDFT

“…This peak has been observed previously, and has prompted debate as to whether it corresponds to a monoanionic form of alizarin or a tautomer. 12,14,20 Figure 2 parts (A), (B), (C), and (D) enumerate the candidate species we consider in this work.…”

Ultrafast Intramolecular Proton Transfer Reaction of 1,2- Dihydroxyanthraquinone in the Excited State

“…1,2-Dihydroxyanthraquinone (alizarin) is one of natural red pigments which forms an intramolecular hydrogen bond between a carbonyl and a hydroxyl group in the ground and excited states [11][12][13][14][15][16][17][18]. Upon photoexcitation, a proton transfer from the hydroxyl to the carbonyl group occurs and the dual emission bands of the locally excited (LE) and proton-transferred (PT) tautomers have been reported [11][12][13][14]. The scheme of electronic structure of alizarin in LE and PT tautomers is shown in Figure 1.…”