Efficient Spin-Orbit Charge-Transfer Intersystem Crossing and Slow Intramolecular Triplet-Triplet Energy Transfer in Bodipy-Perylenebisimide Compact Dyads and Triads

Chen X., Rehmat N., Kurganskii I. V., Maity P., ELMALI A., Zhao J., ...Daha Fazla

CHEMISTRY-A EUROPEAN JOURNAL, cilt.29, 2023 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 29
  • Basım Tarihi: 2023
  • Doi Numarası: 10.1002/chem.202302137
  • Dergi Adı: CHEMISTRY-A EUROPEAN JOURNAL
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Agricultural & Environmental Science Database, Applied Science & Technology Source, Biotechnology Research Abstracts, Chemical Abstracts Core, Chimica, Compendex, EMBASE, MEDLINE
  • Anahtar Kelimeler: charge transfer, intersystem crossing, time-resolved electron paramagnetic resonance, triplet-triplet energy transfer, triplet states, TIME-RESOLVED EPR, PHOTOINDUCED ELECTRON-TRANSFER, RADICAL-ION PAIRS, CYCLOMETALATED IR(III) COMPLEXES, EXCITED-STATE, SINGLET OXYGEN, VISIBLE-LIGHT, PHOTOSENSITIZERS, PHOTOPHYSICS, ANIONS
  • Ankara Üniversitesi Adresli: Evet

Özet

Bodipy (BDP)-perylenebisimide (PBI) donor-acceptor dyads/triad were prepared to study the spin-orbit charge-transfer intersystem crossing (SOCT-ISC). For BDP-PBI-3, in which BDP was attached at the imide position of PBI, higher singlet oxygen quantum yield (& phi;& UDelta;=85 %) was observed than the bay-substituted derivative BDP-PBI-1 (& phi;& UDelta;=30 %). Femtosecond transient absorption spectra indicate slow Forster resonance energy transfer (FRET; 40.4 ps) and charge separation (CS; 1.55 ns) in BDP-PBI-3, while for BDP-PBI-1, CS takes 2.8 ps. For triad BDP-PBI-2, ultrafast FRET (149 fs) and CS (4.7 ps) process were observed, the subsequent charge recombination (CR) takes 5.8 ns and long-lived 3PBI* (179.8 & mu;s) state is populated. Nanosecond transient absorption spectra of BDP-PBI-3 show that the CR gives upper triplet excited state (3BDP*) and subsequently, via a slow intramolecular triplet energy transfer (14.5 & mu;s), the 3PBI* state is finally populated, indicating that upper triplet state is involved in SOCT-ISC. Time-resolved electron paramagnetic resonance spectroscopy revealed that both radical pair ISC (RP ISC) and SOCT-ISC contribute to the ISC. A rare electron spin polarization of (e, e, e, e, e, e) was observed for the triplet state formed via the RP ISC mechanism, due to the S-T+1/T0 states mixing. Intersystem crossing: FRET (40.4 ps) and CS (1.55 ns) were observed, upper 3BDP* was populated by charge recombination, followed by the slow intramolecular TTET (14.5 & mu;s), which generates 3PBI* state, the triplet state formed via the RP ISC shows an unusual ESP phase pattern of (e, e, e, e, e, e), which is a rare example of S-T+1/T0 states mixing in the RP ISC mechanism.+image