Intersystem Crossing, Photo-Induced Charge Separation and Regioisomer-Specific Excited State Dynamics in Fully Rigid Spiro Rhodammine-Naphthalene/Anthraquinone Electron Donor-Acceptor Dyads

Kaiyue Ye; Andrey A Sukhanov; Jiayu Li; Lishan Liu; Xi Chen; Jianzhang Zhao; Violeta K Voronkova; MingDe Li

doi:10.1002/chem.202403758

Intersystem Crossing, Photo-Induced Charge Separation and Regioisomer-Specific Excited State Dynamics in Fully Rigid Spiro Rhodammine-Naphthalene/Anthraquinone Electron Donor-Acceptor Dyads

Chemistry. 2024 Nov 20:e202403758. doi: 10.1002/chem.202403758. Online ahead of print.

Authors

Kaiyue Ye¹, Andrey A Sukhanov², Jiayu Li³, Lishan Liu³, Xi Chen⁴, Jianzhang Zhao⁵, Violeta K Voronkova⁶, MingDe Li³

Affiliations

¹ Dalian University of Technology, State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials, School of Chemical Engineering, 2 Linggong Road, Ganjingzi District, 116024, Dalian, CHINA.
² FSBSI Federal Research Center Kazan Scientific Center of Russian Academy of Sciences: FGBUN Federal'nyj issledovatel'skij centr Kazanskij naucnyj centr Rossijskoj akademii nauk, Zavoisky Physical-Technical Institute, Kazan, RUSSIAN FEDERATION.
³ Shantou University, Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structure Materials of Guangdong Province, CHINA.
⁴ Dalian University of Technology, State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials, School of Chemical Engineering, CHINA.
⁵ Dalian University of Technology, School of Chemical Engineering, State Key Laboratory of Fine Chemicals,, E-208 West Campus,, 2 LingGong Road, Dalian, 116024, P. R. China., 116024, Dalian, CHINA.
⁶ FSBSI Federal Research Center Kazan Scientific Center of Russian Academy of Sciences: FGBUN Federal'nyj issledovatel'skij centr Kazanskij naucnyj centr Rossijskoj akademii nauk, Zavoisky Physical-Technical Institute, RUSSIAN FEDERATION.

PMID: 39567261
DOI: 10.1002/chem.202403758

Abstract

We prepared a series fully rigid spiro electron donor-acceptor orthogonal dyads, with closed form of rhodamine (Rho) as electron donor and naphthalene (Np)/anthraquinone (AQ) as electron acceptor, to access the long-lived triplet charge separation (3CS) state, via the electron spin control method. We found strong dependency of the photophysical property of the dyads on the amino substitution positions of the Np chromophores in the dyads 1,8-DaNp-Rho and 2,3-DaNp-Rho. Nanosecond transient absorption (ns-TA) spectra show the population of the 3LE state (lifetime: 47 μs) for 2,3-DaNp-Rho, however, long-lived 3CS state was observed (τCS = 0.62 μs) for AQ-Rho, with a CS quantum yield of ΦCS = 58%. Based on femtosecond transient absorption (fs-TA) spectra, spin orbit charge transfer ISC (SOCT-ISC) is proposed to be responsible for the formation of the triplet states. Time-resolved electron paramagnetic resonance (TREPR) spectra of AQ-Rho indicate the presence of two states, a 3LE state with zero field splitting (ZFS) D parameter of 1400 MHz and E parameter of -410 MHz, formed via radical pair ISC (RP-ISC) and SOCT-ISC mechanism; and a 3CS state with the electron spin-spin interaction in the regime of spin-correlated radical pair (SCRP).

Keywords: charge separation; electron spin control effect; electron transfer; intersystem crossing; time resolved electron paramagnetic resonance.