The fluorescence spectra of triphenylene (TP) and 2,3,6,7,10,11-hexamethoxy-triphenylene (HMTP) are measured in glass matrices, and the vibronic structure associated with the electronic spectra is simulated with the help of quantum chemically computed molecular parameters. Franck-Condon (FC) and Herzberg-Teller (HT) mechanisms are included. For excited-state calculations, both configuration interaction with single excitations (CIS) and time-dependent density functional theory (TDDFT) are employed. It is shown that the FC activity is associated with modes of similar shape and frequency in both molecules, while the HT-induced false origins with the largest activity are associated with rather different frequencies and normal coordinates as a result of the mixing and energy lowering of the low-lying allowed excited states in HMTP. The increased HT activity explains the reduced S1 state lifetime in the substituted TP, in turn driven by the excited-state rearrangement occurring upon substitution of the TP core.
E. Di Donato, D. Vanzo, M. Semeraro, A. Credi, F. Negri (2009). Tuning Fluorescence Lifetimes through Changes in Herzberg-Teller Activities: The Case of Triphenylene and Its Hexamethoxy-Substituted Derivative. JOURNAL OF PHYSICAL CHEMISTRY. A, MOLECULES, SPECTROSCOPY, KINETICS, ENVIRONMENT, & GENERAL THEORY, 113, 6504-6510 [10.1021/jp9005247].
Tuning Fluorescence Lifetimes through Changes in Herzberg-Teller Activities: The Case of Triphenylene and Its Hexamethoxy-Substituted Derivative
DI DONATO, EUGENIO;SEMERARO, MONICA;CREDI, ALBERTO;NEGRI, FABRIZIA
2009
Abstract
The fluorescence spectra of triphenylene (TP) and 2,3,6,7,10,11-hexamethoxy-triphenylene (HMTP) are measured in glass matrices, and the vibronic structure associated with the electronic spectra is simulated with the help of quantum chemically computed molecular parameters. Franck-Condon (FC) and Herzberg-Teller (HT) mechanisms are included. For excited-state calculations, both configuration interaction with single excitations (CIS) and time-dependent density functional theory (TDDFT) are employed. It is shown that the FC activity is associated with modes of similar shape and frequency in both molecules, while the HT-induced false origins with the largest activity are associated with rather different frequencies and normal coordinates as a result of the mixing and energy lowering of the low-lying allowed excited states in HMTP. The increased HT activity explains the reduced S1 state lifetime in the substituted TP, in turn driven by the excited-state rearrangement occurring upon substitution of the TP core.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
