title: Theoretical studies on absorption, emission, and resonance Raman spectra of Coumarin 343 isomers.
abstract: The vibrationally resolved spectral method and quantum chemical calculations are employed to reveal the structural and spectral properties of Coumarin 343 (C343), an ideal candidate for organic dye photosensitizers, in vacuum and solution. The results manifest that the ground-state energies are dominantly determined by different placements of hydrogen atom in carboxylic group of C343 conformations. Compared to those in vacuum, the electronic absorption spectra in methanol solvent show a hyperchromic property together with the redshift and blueshift for the neutral C343 isomers and their deprotonated anions, respectively. From the absorption, emission, and resonance Raman spectra, it is found that the maximal absorption and emission come from low-frequency modes whereas the high-frequency modes have high Raman activities. The detailed spectra are further analyzed for the identification of the conformers and understanding the potential charge transfer mechanism in their photovoltaic applications.
authors.affiliation: State Key Laboratory for Physical Chemistry of Solid Surfaces and Fujian Provincial Key Lab of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, People's Republic of China.
authors.forename: Wenpeng
authors.initials: W
authors.lastname: Wu
authors.forename: Zexing
authors.initials: Z
authors.lastname: Cao
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D003374:Coumarins / Q000737:chemistry*; D015394:Molecular Structure; D011789:Quantum Theory; D013059:Spectrum Analysis, Raman; D013237:Stereoisomerism
chemical_list: D003374:Coumarins; C552279:coumarin 343