Spin-Orbit Charge-Transfer Intersystem Crossing of Compact Naphthalenediimide-Carbazole Electron-Donor-Acceptor Triads

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Hussain, Mushraf (författare)

Spin-Orbit Charge-Transfer Intersystem Crossing of Compact Naphthalenediimide-Carbazole Electron-Donor-Acceptor Triads

Artikel/kapitelEngelska2021

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2021-09-20
American Chemical Society (ACS),2021
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Nummerbeteckningar

LIBRIS-ID:oai:DiVA.org:su-198840
https://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-198840URI
https://doi.org/10.1021/acs.jpcb.1c06498DOI

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Språk:engelska
Sammanfattning på:engelska

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Ämneskategori:art swepub-publicationtype

Anmärkningar

Compact electron donor–acceptor triads based on carbazole (Cz) and naphthalenediimide (NDI) were prepared to study the spin–orbit charge-transfer intersystem crossing (SOCT-ISC). By variation of the molecular conformation and electron-donating ability of the carbazole moieties, the electronic coupling between the two units was tuned, and as a result charge-transfer (CT) absorption bands with different magnitudes were observed (ε = 4000–18 000 M–1 cm–1). Interestingly, the triads with NDI attached at the 3-C position or with a phenyl spacer at the N position of the Cz moiety, thermally activated delayed fluorescence (TADF) was observed. Femtosecond transient absorption (fs-TA) spectroscopy indicated fast electron transfer (0.8–1.5 ps) from the Cz to NDI unit, followed by population of the triplet state (150–600 ps). Long-lived triplet states (up to τT = 45–50 μs) were observed for the triads. The solvent-polarity-dependent singlet-oxygen quantum yield (ΦΔ) is 0–26%. Time-resolved electron paramagnetic resonance (TREPR) spectral study of TADF molecules indicated the presence of the 3CT state for NDI-Cz-Ph (zero-field-splitting parameter D = 21 G) and an 3LE state for NDI-Ph-Cz (D = 586 G). The triads were used as triplet photosensitizers in triplet–triplet annihilation upconversion by excitation into the CT absorption band; the upconversion quantum yield was ΦUC = 8.2%, and there was a large anti-Stokes shift of 0.55 eV. Spatially confined photoexcitation is achieved with the upconversion using focusing laser beam excitation, and not the normally used collimated laser beam, i.e., the upconversion was only observed at the focal point of the laser beam. Photo-driven intermolecular electron transfer was demonstrated with reversible formation of the NDI–• radical anion in the presence of the sacrificial electron donor triethanolamine.

Ämnesord och genrebeteckningar

NATURVETENSKAP Kemi hsv//swe
NATURAL SCIENCES Chemical Sciences hsv//eng

Biuppslag (personer, institutioner, konferenser, titlar ...)

El-Zohry, Ahmed M.Stockholms universitet,Fysikum,King Abdullah University of Science and Technology (KAUST), Kingdom of Saudi Arabia(Swepub:su)ahel6312 (författare)
Hou, Yuqi (författare)
Toffoletti, Antonio (författare)
Zhao, Jianzhang (författare)
Barbon, Antonio (författare)
Mohammed, Omar F. (författare)
Stockholms universitetFysikum (creator_code:org_t)

Sammanhörande titlar

Ingår i:Journal of Physical Chemistry B: American Chemical Society (ACS)125:38, s. 10813-108311520-61061520-5207

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Av författaren/redakt...: Hussain, Mushraf; El-Zohry, Ahmed ...; Hou, Yuqi; Toffoletti, Anto ...; Zhao, Jianzhang; Barbon, Antonio; visa fler...; Mohammed, Omar F ...; visa färre...

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