Isotopic effect and temperature dependent intramolecular excitation energy transfer in a model donor–acceptor dyad

Abstract

We consider here the non-adiabatic energy transfer dynamics for a model bi-chromophore system consisting of a perylenediimide unit linked to a ladder-type poly-(para-phenylene) oligomer. Starting from a semi-empirical parameterization of a model electron/phonon Hamiltonian, we compute the golden-rule rate for energy transfer from the LPPP5 donor to the PDI acceptor. Our results indicate that the non-adiabatic transfer is promoted by the out-of-plane wagging modes of the C-H bonds even though theses modes give little or no contribution to the Franck Condon factors in this system. We also predict a kinetic isotope effect of k (H) /k (D) = 1.7 − 2.5 depending upon the temperature.

Ultrafast energy transfer of one-dimensional excitons between carbon nanotubes: a femtosecond time-resolved luminescence study

“…Namely, the conventional Fo¨rster mechanism is irrelevant to such EET. The failure of the conventional Fo¨rster model has been observed in lightharvesting complexes, [5][6][7][8][9][10][11][12][13][14][15] conjugated polymers, [16][17][18][19][20] and DNA; 21 comprehensive descriptions and citations are provided in, for example, a PCCP themed issue on electronic energy transfer [22][23][24][25][26][27][28][29][30][31][32][33][34][35] as well as in ref. 36 and 37.…”

Ultrafast Non-Förster Intramolecular Donor–Acceptor Excitation Energy Transfer

“…This partially delocalized character of the excited state over the donor and acceptor units can explain our faster relaxation times compared with previous calculated golden-rule rates by Singh and Bittner. 30 The interaction between S 2 (initially localized on the donor unit) and S 1 (initially localized on the acceptor unit) states is revealed in the ultrafast increase of the nonadiabatic coupling (see Figure 4b), reaching a maximum in ∼5 fs. Both states remain coupled for the first 100 fs after photoexcitation.…”

“…Here we present theoretical results for the dynamics of energy transfer in a molecular dyad system comprising a ladder-type poly­(para-phenylene) oligomer donor unit (LPPP5) covalently linked with a perylenemonoimide acceptor unit (PMI) (see Figure a). This system has been studied in the past by Singh and Bittner who predicted a kinetic isotope effect using Fermi’s golden rule within a harmonic approximation. Ladder-type poly­(para-phenylene) are used as hosts in electroluminescent devices and solar cells, whereas perylenes are key components in next-generation solar cells, in particular dye-sensitized cells .…”

Vibrational energy redistribution during donor–acceptor electronic energy transfer: criteria to identify subsets of active normal modes

“…Intramolecular vibrational energy transfer in organic molecules is commonly simulated with effective Hamiltonians by applying harmonic approximations to identify the pathways and lifetimes of a specific mode or bond energy relaxation 51,52,53 . For example, using a parametrized Hamiltonian describing the coupling between a set of discrete electronic states with a set of phonon oscillators in combination with golden-rule transfer rates, Bittner et al were able to identify active electron transfer vibrational coordinates in donor-acceptor systems 54,55,56,57,58 . Vibrational energy relaxation and redistribution can be monitored following the evolution in time of the kinetic energy of each ENM.…”

“…In a previous publication, we reported an ultrafast donoracceptor intramolecular electronic energy transfer in the molecular dyad system comprising a ladder-type poly(paraphenylene) oligomer donor unit (LPPP5) covalently linked with a perylenemonoimide acceptor unit (PMI) (see Figure 1a) 59,54 . In this contribution, we shall characterize the role of vibrational energy redistribution during the internal conversion process of the model LPPP5-PMI dyad system using atomistic non-adiabatic excited-state molecular dynamics (NEXMD) simulations.…”