Projects per year
Abstract
Organic substitutes for ruthenium and iridium complexes are increasingly finding applications in chemical syntheses involving photoredox catalysis. However, the performance of these organic compounds as electron-transfer photocatalysts depends on their accessible photochemical pathways and excited state lifetimes. Here, the UV-induced dynamics of N-phenyl phenoxazine, chosen as a prototypical N-aryl phenoxazine organic photoredox catalyst, are explored in three solvents, N,N-dimethyl formamide, dichloromethane and toluene, using ultrafast transient absorption spectroscopy. Quantum chemistry calculations reveal the locally excited or charge-transfer electronic character of the excited states, and are used to assign the transient electronic and vibrational bands observed. In toluene-d8, complete ground-state recovery is (31 ± 3) % by internal conversion (IC) from the photo-excited state (or from S1 after IC but before complete vibrational relaxation), (13 ± 2) % via direct decay from vibrationally relaxed S1 (most likely radiative decay, with an estimated radiative lifetime of 13 ns) and (56 ± 3) % via the T1 state (with intersystem crossing (ISC) rate coefficient kISC = (3.3 ± 0.2) ± 108 s-1). In dichloromethane, we find evidence for excited state N-phenyl phenoxazine reaction with the solvent. Excited state lifetimes, ISC rates, and ground-state recovery show only modest variation with changes to the solvent environment because of the locally excited character of the S1 and T1 states.
Original language | English |
---|---|
Pages (from-to) | 1475 - 1494 |
Journal | Zeitschrift für Physikalische Chemie |
Volume | 234 |
Early online date | 9 Jun 2020 |
DOIs | |
Publication status | Published - 27 Aug 2020 |
Structured keywords
- BCS and TECS CDTs
Keywords
- photochemistry
- transient absorption spectroscopy
- ultrafast dynamics
- organic photocatalyst
Fingerprint
Dive into the research topics of 'Solvent-dependent photochemical dynamics of a phenoxazine-based photoredox catalyst'. Together they form a unique fingerprint.Projects
- 2 Finished
-
-
Mapping Pathways in Photocatalytic Cycles using Ultrafast Spectroscopy
1/03/18 → 28/02/21
Project: Research
Student Theses
-
Ab initio methods for atmospheric photochemistry
Author: Shchepanovska, D., 28 Sep 2021Supervisor: Glowacki, D. (Supervisor) & Orr-Ewing, A. (Supervisor)
Student thesis: Doctoral Thesis › Doctor of Philosophy (PhD)
File