RT Journal Article
T1 A computational study of the vibronic effects on the electronic spectra and the photophysics of aza[7]helicene
A1 Liu, Yanli
A1 Aranda, Daniel
A1 Santoro, Fabrizio
K1 Helicenos
AB We report a computational study on vibronic effects in the spectroscopy, photoinduced processes anddecay back to the ground state of aza[7]helicene, a helicene with an unusually high fluorescencequantum yield (QY = 0.39). In a first step, we compute and assign the absorption and electronic circulardichroism (ECD) spectra in its full frequency range from 2.7 to 5.0 eV, accounting for nonadiabatic effects.Then we compute the quantum dynamics of the cascade of ultrafast internal conversions of the highlyexcited singlet states to the lowest-energy one S1. Finally we adopt Fermi golden rule rates to compute theQY of the dye, taking into account the competition between the radiative decay and the nonradiative decaysto the ground state and to the energy-accessible triplet states. We use time-dependent density functionaltheory (TD-DFT), including solvent (dichloromethane) effects within the polarizable continuum model, toparameterize a linear vibronic coupling (LVC) model involving the first lowest 12 singlet states and all thenormal coordinates. Nonadiabatic spectra and internal conversions dynamics are then computed throughwavepacket propagations with the Multilayer (ML) extension of the Multiconfigurational Time DependentHartree method (ML-MCTDH). We highlight the molecular vibrations playing a major role in determining theshape of the spectra and analyse the effect of inter-state couplings. At the same time we report a breakdownof perturbative Herzberg–Teller approach. The computed QY is in perfect agreement with experiment andallows us to ascertain that intersystem crossings are the processes limiting the fluorescence from S1. Theyinvolve the three lowest triplet states and are made effective by spin–orbit coupling and vibronic effects.
PB Royal Society of Chemistry
YR 2021
FD 2021-07-19
LK https://hdl.handle.net/10630/37138
UL https://hdl.handle.net/10630/37138
LA spa
NO Yanli Liu, Daniel Aranda and Fabrizio Santoro. A computational study of the vibronic effects on the electronic spectra and the photophysics of aza[7]helicene. : Phys. Chem. Chem. Phys., 2021, 23, 16551. DOI: 10.1039/d1cp00822f
DS RIUMA. Repositorio Institucional de la Universidad de Málaga
RD 20 ene 2026