TY - JOUR

T1 - A long-lived charge-separated state of spiro compact electron donor-acceptor dyads based on rhodamine and naphthalenediimide chromophores

AU - Xiao, Xiao

AU - Kurganskii, Ivan

AU - Maity, Partha

AU - Zhao, Jianzhang

AU - Jiang, Xiao

AU - Mohammed, Omar F.

AU - Fedin, Matvey

N1 - Funding Information: J. Z. thanks the NSFC (U2001222), the State Key Laboratory of Fine Chemicals, the Fundamental Research Funds for the Central Universities (DUT22LAB610) and the Department of Education of the Xinjiang Uyghur Autonomous Region (Tian-Shan Chair Professor) for financial support. M. F. and I. K. thank the Ministry of Science and Higher Education of the Russian Federation (Grant No. 075-15-2020-779). Publisher Copyright: © 2022 The Royal Society of Chemistry.

PY - 2022/10/26

Y1 - 2022/10/26

N2 - Spiro rhodamine (Rho)-naphthalenediimide (NDI) electron donor-acceptor orthogonal dyads were prepared to generate a long-lived charge separation (CS) state based on the electron spin control approach, i.e. to form the 3CS state, not the 1CS state, to prolong the CS state lifetime by the electron spin forbidden feature of the charge recombination process of 3CS → S0. The electron donor Rho (lactam form) is attached via three σ bonds, including two C-C and one N-N bonds (Rho-NDI), or an intervening phenylene, to the electron acceptor NDI (Rho-Ph-NDI and Rho-PhMe-NDI). Transient absorption (TA) spectra show that fast intersystem crossing (ISC) (<120 fs) occurred to generate an upper triplet state localized on the NDI moiety (3NDI*), and then to form the CS state. For Rho-NDI in both non-polar and polar solvents, a long-lived 3CS state (lifetime τ = 0.13 μs) and charge separation quantum yield (ΦCS) up to 25% were observed, whereas for Rho-Ph-NDI (τT = 1.1 μs) and Rho-PhMe-NDI (τT = 2.0 μs), a low-lying 3NDI* state was formed by charge recombination (CR) in n-hexane (HEX). In toluene (TOL), however, CS states were observed for Rho-Ph-NDI (0.37 μs) and Rho-PhMe-NDI (0.63 μs). With electron paramagnetic resonance (EPR) spectra, weak electronic coupling between the Rho and NDI moieties for Rho-NDI was proved. Time-resolved EPR (TREPR) spectra detected two transient species including NDI-localized triplets (formed via SOC-ISC) and a 3CS state. The CS state of Rho-NDI features the largest dipolar interaction (|D| = 184 MHz) compared to Rho-Ph-NDI (|D| = 39 MHz) and Rho-PhMe-NDI (|D| = 41 MHz) due to the smallest distance between Rho and NDI moieties. For Rho-NDI, the time-dependent e,a → a,e phase change of the CS state TREPR spectrum indicates that the long-lived CS state is based on the electron spin control effect.

AB - Spiro rhodamine (Rho)-naphthalenediimide (NDI) electron donor-acceptor orthogonal dyads were prepared to generate a long-lived charge separation (CS) state based on the electron spin control approach, i.e. to form the 3CS state, not the 1CS state, to prolong the CS state lifetime by the electron spin forbidden feature of the charge recombination process of 3CS → S0. The electron donor Rho (lactam form) is attached via three σ bonds, including two C-C and one N-N bonds (Rho-NDI), or an intervening phenylene, to the electron acceptor NDI (Rho-Ph-NDI and Rho-PhMe-NDI). Transient absorption (TA) spectra show that fast intersystem crossing (ISC) (<120 fs) occurred to generate an upper triplet state localized on the NDI moiety (3NDI*), and then to form the CS state. For Rho-NDI in both non-polar and polar solvents, a long-lived 3CS state (lifetime τ = 0.13 μs) and charge separation quantum yield (ΦCS) up to 25% were observed, whereas for Rho-Ph-NDI (τT = 1.1 μs) and Rho-PhMe-NDI (τT = 2.0 μs), a low-lying 3NDI* state was formed by charge recombination (CR) in n-hexane (HEX). In toluene (TOL), however, CS states were observed for Rho-Ph-NDI (0.37 μs) and Rho-PhMe-NDI (0.63 μs). With electron paramagnetic resonance (EPR) spectra, weak electronic coupling between the Rho and NDI moieties for Rho-NDI was proved. Time-resolved EPR (TREPR) spectra detected two transient species including NDI-localized triplets (formed via SOC-ISC) and a 3CS state. The CS state of Rho-NDI features the largest dipolar interaction (|D| = 184 MHz) compared to Rho-Ph-NDI (|D| = 39 MHz) and Rho-PhMe-NDI (|D| = 41 MHz) due to the smallest distance between Rho and NDI moieties. For Rho-NDI, the time-dependent e,a → a,e phase change of the CS state TREPR spectrum indicates that the long-lived CS state is based on the electron spin control effect.

UR - http://www.scopus.com/inward/record.url?scp=85142323671&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/9e5018ae-fc0a-3d48-b803-496961eb325d/

U2 - 10.1039/d2sc04258d

DO - 10.1039/d2sc04258d

M3 - Article

C2 - 36507154

AN - SCOPUS:85142323671

VL - 13

SP - 13426

EP - 13441

JO - Chemical Science

JF - Chemical Science

SN - 2041-6520

IS - 45

ER -