title: Theoretical characterization of absorption and emission spectra of an asymmetric porphycene.
abstract: The electronic ground and excited states of an asymmetric porphycene, 9-amino-2,7,12,17-tetraphenylporphycene (9-ATPPo), are investigated by electronic structure calculations. Different tautomers are considered to address their contributions to the photophysics of 9-ATPPo. Tautomerization pathways on the ground and excited states are constructed between different isomers. It is found that two trans tautomers are mainly responsible for the absorption and emission spectra of 9-ATPPo. These calculations provide a molecular mechanism to explain recent experimental observations, which show a highly complex Q-band structure in the absorption spectrum and pronounced dual fluorescence in the emission spectrum. Furthermore, the current work shows that tautomerization takes place under the assistance of cavity deformations and that a nonradiative process occurs through weak interstate nonadiabatic couplings near the S(1) minimum rather than strong ones near conical intersections.
authors.affiliation: Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, People's Republic of China. lanzg@qibebt.ac.cn
authors.forename: Zhenggang
authors.initials: Z
authors.lastname: Lan
authors.forename: Santi
authors.initials: S
authors.lastname: Nonell
authors.forename: Mario
authors.initials: M
authors.lastname: Barbatti
mesh_terms: D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011166:Porphyrins / Q000737:chemistry*; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence; D013237:Stereoisomerism; D013696:Temperature
chemical_list: C574475:9-amino-2,7,12,17-tetraphenylporphycene; D011166:Porphyrins