Electron Spin Dynamics of the Intersystem Crossing in Aminoanthraquinone Derivatives: The Spectral Telltale of Short Triplet Excited States
Year: 2024
Type: article
Abstract: We studied the excited state dynamics of two bis-amino substituted anthraquinone (AQ) derivatives, with absorption in the visible spectral region, which results from the attachment of a electron-donating group to the electron-deficient AQ chromophore. Femtosecond transient absorption spectra show that intersystem crossing (ISC) takes place in 190–320 ps, and nanosecond transient absorption spectra demonstrated an unusually short triplet state lifetime (2.06–5.43 μs) for the two AQ derivatives. Pulsed laser-excited time-resolved electron paramagnetic resonance (TREPR) spectra show an inversion of the electron spin polarization (ESP) phase pattern of the triplet state at a longer delay time after laser flash. Spectral simulations show faster decay of the T y sublevel than the other two sublevels (τ x = 15.0 μs, τ y = 1.50 μs, τ z = 15.0 μs); theoretical computation predicts initial overpopulation of the T y sublevel, and rationalizes the short T 1 state lifetime and the ESP inversion. Theoretical computations taking into account the electron-vibrational coupling, i.e., the Herzberg–Teller effect, successfully rationalize the TREPR experimental observations.
Institutions: Dalian University of Technology, State Key Laboratory of Fine Chemicals, Russian Academy of Sciences, Kazan Scientific Center, Kazan E. K. Zavoisky Physical-Technical Institute, KU Leuven, European Laboratory for Non-Linear Spectroscopy, Institute for the Chemistry of OrganoMetallic Compounds
Language: English
Subfield: Physical and Theoretical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
Funders: European Commission, National Natural Science Foundation of China, Russian Foundation for Basic Research, Dalian University of Technology, Fonds Wetenschappelijk Onderzoek, KU Leuven, Università degli Studi di Firenze, Russian Academy of Sciences, National Key Research and Development Program of China, Fundamental Research Funds for the Central Universities, H2020 Research Infrastructures, Kazan Scientific Centre, Russian Academy of Sciences
Awards: G1295293814, The Integrated Initiative of European Laser Research Infrastructures, G17901752, G2112164636, The Integrated Initiative of European Laser Research Infrastructures, G4292930477, Unraveling complex Excited States properties from first-principles (complexES), G6908658743, G7434957422, G7466102155
OpenAlex ID: W4403138460