title: Influence of Duschinsky and Herzberg-Teller effects on S₀→ S₁ vibrationally resolved absorption spectra of several porphyrin-like compounds.
abstract: The S0 → S1 (Q band) high-resolved absorption spectra of three porphyrin-like compounds, porphycene, magnesium porphyrin, and zinc tetraazaporphyrin, were simulated in the framework of the Franck-Condon approximation including the Duschinsky and Herzberg-Teller (HT) contributions. Substitution of meso-aza on porphyrin macrocycle framework could change severely the absorption energy, vibrational intensity, and spectral profile of Q band. Therefore, we focused attention on the spectral similarities and contrasts among the three compounds based on the density functional theory and its time-dependent extension calculations. The simulated spectra agreed well with the experimental ones and further confirmed that the HT and Duschinsky effects have significant influence on the weakly allowed or forbidden transition of sizable organic molecules. The pure HT and Duschinsky effects were explored separately to clarify their contributions on changing vibrational intensities of different modes. Moreover, we tentatively assigned most of the vibrational modes which appeared in the experimental spectra but corresponding assignments were not given. The present work provided a useful method to simulate and interpret the absorption spectra of porphyrin-like compounds.
authors.affiliation: College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.
authors.forename: Pan
authors.initials: P
authors.lastname: Yang
authors.affiliation: College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Qi
authors.affiliation: College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.
authors.forename: Guojian
authors.initials: G
authors.lastname: You
authors.affiliation: College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Shen
authors.affiliation: College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.affiliation: College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China.
authors.forename: Rongxing
authors.initials: R
authors.lastname: He
mesh_terms: D003198:Computer Simulation; D017616:Magnesium Compounds / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D055668:Photochemical Processes; D011166:Porphyrins / Q000737:chemistry*; D013057:Spectrum Analysis; D014732:Vibration; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D017616:Magnesium Compounds; D011166:Porphyrins; D017967:Zinc Compounds; C051407:porphycene