Long-Lived Charge Separated States in Anthraquinone-Phenothiazine Dyads: Synthesis and Study of the Photophysical Property by Using Transient Optical and Magnetic Resonance Spectroscopies

Year: 2023

Authors: Wang H., Sukhanov A. A., Iagatti A., Bussotti L., Zhao X., Zhao J., Voronkova V. K., Di Donato M.

Autors Affiliation: Dalian Univ Technol, Frontiers Sci Ctr Smart Mat, Sch Chem Engn, State Key Lab Fine Chem, E 208 West Campus, 2 Ling Gong Rd, Dalian 116024, Peoples R China; Russian Acad Sci, Zavoisky Phys Tech Inst, FRC Kazan Sci Ctr, Kazan 420029, Russia; LENS European Lab Nonlinear Spect, Via N Carrara 1, I-50019 Sesto Fiorentino FI, Italy; INO CNR, Largo Enr Fermi 6, I-50125 Firenze FI, Italy; Xinjiang Univ, Coll Chem, State Key Lab Chem & Utilizat Carbon Based Energy, Urumqi 830017, Peoples R China; ICCOM CNR, Via Madonna Piano 10, I-50019 Sesto Fiorentino FI, Italy.

Abstract: In order to obtain long-lived charge separated (CS) states in electron donor-acceptor dyads, herein we prepared a series of anthraquinone (AQ)-phenothiazine (PTZ) dyads, with adamantane as the linker. UV–vis absorption spectra show negligible electronic interaction between the AQ and PTZ units at ground state, yet charge transfer (CT) emission bands were observed. Nanosecond transient absorption shows that the 3AQ state is populated upon photoexcitation for AQ-PTZ in cyclohexane (CHX), but in acetonitrile (ACN) a 3CS state is formed. Similar results were observed for AQ-PTZ-M. The 3CS state lifetimes were determined as 0.52 μs and 0.49 μs, respectively. Upon oxidation of the PTZ unit, the 3AQ state was observed in both polar and non-polar solvents. For AQ-PTZ, femtosecond transient absorption spectra show fast formation of the 3AQ state in all solvents, with no charge separation in CHX, while formation of the 3CS state takes 106 ps in ACN. For AQ-PTZ-M, a 3CS state is formed in CHX within 241 ps. Time-resolved electron paramagnetic resonance (TREPR) spectra show that a radical ion pair with electron exchange energy of |2 J|≥5.68 mT was observed for AQ-PTZ and AQ-PTZ-M, whereas in the dyads with the PTZ unit oxidized, only the 3AQ state was observed.

Journal/Review: CHEMISTRY-A EUROPEAN JOURNAL

Volume: 29 (43)      Pages from: e202301125-1  to: e202301125-13

More Information: J. Z. thanks the NSFC (U2001222), the Research and Innovation Team Project of Dalian University of Technology (DUT2022TB10), the Fundamental Research Funds for the Central Universities (DUT22LAB610) and the State Key Laboratory of Fine Chemicals for financial support. A.A.S. and V.K.V. acknowledge financial support from the government assignment for FRC Kazan Scientific Centre of RAS. M.D.D. thanks the European Union´s Horizon 2020 research and innovation program under grant agreement n. 871124 Laserlab-Europe for the support.
KeyWords: Aromatic compounds; Electromagnetic wave absorption; Electron resonance; Electron spin resonance spectroscopy; Electron transitions; Free radical reactions; Ground state; Insecticides; Ion exchange; Ketones; Paramagnetic resonance; Paramagnetism; Charge transfer
DOI: 10.1002/chem.202301125

Citations: 3
data from “WEB OF SCIENCE” (of Thomson Reuters) are update at: 2024-11-17
References taken from IsiWeb of Knowledge: (subscribers only)
Connecting to view paper tab on IsiWeb: Click here
Connecting to view citations from IsiWeb: Click here