Observation of Long-Lived Charge-Separated States in Anthraquinone-Phenothiazine Electron Donor-Acceptor Dyads: Transient Optical and Electron Paramagnetic Resonance Spectroscopic Studies

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216305%3A26620%2F23%3APU149139" target="_blank" >RIV/00216305:26620/23:PU149139 - isvavai.cz</a>

Výsledek na webu

<a href="https://pubs.acs.org/doi/10.1021/acs.jpcb.3c02723" target="_blank" >https://pubs.acs.org/doi/10.1021/acs.jpcb.3c02723</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1021/acs.jpcb.3c02723" target="_blank" >10.1021/acs.jpcb.3c02723</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Observation of Long-Lived Charge-Separated States in Anthraquinone-Phenothiazine Electron Donor-Acceptor Dyads: Transient Optical and Electron Paramagnetic Resonance Spectroscopic Studies

Popis výsledku v původním jazyce

We prepared a series of phenothiazine (PTZ)-anthraquinone(AQ) electron donor-acceptor dyads to study the relationshipbetween molecular structures and the possibility of charge transfer(CT) and intersystem crossing (ISC). As compared to the previouslyreported PTZ-AQ dyad with a direct connection of twounits via a C-N single bond, the PTZ and AQ units are connectedvia a p-phenylene or p-biphenylenelinker. Conformation restriction is imposed by attaching ortho-methyl groups on the phenylene linker. UV-vis absorptionspectra indicate electronic coupling between the PTZ and AQ unitsin the dyads without conformation restriction. Different from thepreviously reported PTZ-AQ, thermally activated delayedfluorescence (TADF) is observed for the dyads containing one phenylenelinker (PTZ-Ph-AQ and PTZ-PhMe-AQ). Theprompt fluorescence lifetime in cyclohexane is exceptionally long(& tau;(PF) = 62.0 ns, population ratio: 99.2%) and 245.0ns (93.5%) for PTZ-Ph-AQ and PTZ-PhMe-AQ, respectively (normally & tau;(PF) <20 ns); the delayedfluorescence lifetimes for these two dyads were determined as & tau;(DF) = 2.4 & mu;s (6.5%) and 7.6 & mu;s (0.8%), respectively.For the dyad containing a biphenylene linker (PTZ-Ph ( 2 ) Me-AQ), no TADF was observed. Charge-separated(CS) states were observed for PTZ-Ph-AQ and PTZ-PhMe-AQ, and the lifetimes were determined as 7.0 and 1.3 & mu;s, respectively,indicating the triplet spin multiplicity of the CS state. The (CS)-C-3 state lifetimes are shortened to 100 ns and 440 ns forthe two dyads, respectively, in the polar solvent acetonitrile. Fordyads with a longer linker, i.e., PTZ-Ph ( 2 ) Me-AQ, the CS state lifetime is not sensitiveto solvent polarity (& tau;(CS) = 1.8 and 1.3 & mu;s incyclohexane and acetonitrile, respectively). In reference dyads, wherethe PTZ unit is oxidized to sulfoxide, no CT absorption band and TADFwere observed, which is attributed to the increased CS state energy(>3 eV) becoming higher than that of the AQ triplet ((3)AQ*)stat

Název v anglickém jazyce

Observation of Long-Lived Charge-Separated States in Anthraquinone-Phenothiazine Electron Donor-Acceptor Dyads: Transient Optical and Electron Paramagnetic Resonance Spectroscopic Studies

Popis výsledku anglicky

We prepared a series of phenothiazine (PTZ)-anthraquinone(AQ) electron donor-acceptor dyads to study the relationshipbetween molecular structures and the possibility of charge transfer(CT) and intersystem crossing (ISC). As compared to the previouslyreported PTZ-AQ dyad with a direct connection of twounits via a C-N single bond, the PTZ and AQ units are connectedvia a p-phenylene or p-biphenylenelinker. Conformation restriction is imposed by attaching ortho-methyl groups on the phenylene linker. UV-vis absorptionspectra indicate electronic coupling between the PTZ and AQ unitsin the dyads without conformation restriction. Different from thepreviously reported PTZ-AQ, thermally activated delayedfluorescence (TADF) is observed for the dyads containing one phenylenelinker (PTZ-Ph-AQ and PTZ-PhMe-AQ). Theprompt fluorescence lifetime in cyclohexane is exceptionally long(& tau;(PF) = 62.0 ns, population ratio: 99.2%) and 245.0ns (93.5%) for PTZ-Ph-AQ and PTZ-PhMe-AQ, respectively (normally & tau;(PF) <20 ns); the delayedfluorescence lifetimes for these two dyads were determined as & tau;(DF) = 2.4 & mu;s (6.5%) and 7.6 & mu;s (0.8%), respectively.For the dyad containing a biphenylene linker (PTZ-Ph ( 2 ) Me-AQ), no TADF was observed. Charge-separated(CS) states were observed for PTZ-Ph-AQ and PTZ-PhMe-AQ, and the lifetimes were determined as 7.0 and 1.3 & mu;s, respectively,indicating the triplet spin multiplicity of the CS state. The (CS)-C-3 state lifetimes are shortened to 100 ns and 440 ns forthe two dyads, respectively, in the polar solvent acetonitrile. Fordyads with a longer linker, i.e., PTZ-Ph ( 2 ) Me-AQ, the CS state lifetime is not sensitiveto solvent polarity (& tau;(CS) = 1.8 and 1.3 & mu;s incyclohexane and acetonitrile, respectively). In reference dyads, wherethe PTZ unit is oxidized to sulfoxide, no CT absorption band and TADFwere observed, which is attributed to the increased CS state energy(>3 eV) becoming higher than that of the AQ triplet ((3)AQ*)stat

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10403 - Physical chemistry

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2023

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

JOURNAL OF PHYSICAL CHEMISTRY B

ISSN

1520-6106

e-ISSN

1520-5207

Svazek periodika

127

Číslo periodika v rámci svazku

26

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

19

Strana od-do

5905-5923

Kód UT WoS článku

001018075300001

EID výsledku v databázi Scopus

2-s2.0-85164244685