Electronic Coupling and Spin–Orbit Charge-Transfer
Intersystem Crossing in Phenothiazine–Perylene Compact Electron
Donor/Acceptor Dyads
Muhammad Imran
Andrey A. Sukhanov
Zhijia Wang
Ahmet Karatay
Jianzhang Zhao
Zafar Mahmood
Ayhan Elmali
Violeta K. Voronkova
Mustafa Hayvali
Yong Heng Xing
Stefan Weber
10.1021/acs.jpcc.8b12040.s001
https://acs.figshare.com/articles/journal_contribution/Electronic_Coupling_and_Spin_Orbit_Charge-Transfer_Intersystem_Crossing_in_Phenothiazine_Perylene_Compact_Electron_Donor_Acceptor_Dyads/7857695
We
prepared perylene (Pery)-phenothiazine (PTZ) compact donor/acceptor
dyads with connection at either N- or 2-C positions of the PTZ moiety
to attain molecular conformation restriction and to study the relationship
between mutual chromophore orientation and spin–orbit charge-transfer
intersystem crossing (SOCT-ISC) efficiency. In <b>Pery-N-PTZ</b>, the linkage is at the N-position of the PTZ moiety, and the molecule
adopts an orthogonal geometry (φ = 91.5°), whereas in <b>Pery-C-PTZ</b>, the connection is at the 2-C position, resulting
in a more planar geometry (φ = 60.6°). A diphenylamino
derivative (<b>Pery-DPA</b>) was also prepared in which a N
atom is fully π-conjugated with the perylene moiety. Highly
solvent polarity-dependent singlet oxygen production was observed
for the dyads (Φ<sub>Δ</sub> = 3–60%), which is
an indication of the SOCT-ISC mechanism. The potential energy curve
of the torsion about the C–N/C–C linker indicated different
energy landscapes for the dyads; interestingly, we found that nonorthogonal
geometry also induces efficient SOCT-ISC, which is different from
previous studies. The ultrafast charge separation process (<100
fs) and the ISC rate (0.27 ps) were observed by femtosecond transient
absorption spectroscopy. Time-resolved electron paramagnetic resonance
spectroscopy further confirmed the SOCT-ISC mechanism. With perylenebisimide
as the triplet acceptor and the dyads as the triplet photosensitizer,
the triplet–triplet annihilation-induced delayed fluorescence
was observed, with the luminescence lifetime up to 71 μs.
2019-03-01 00:00:00
PTZ moiety
perylene
2- C position
triplet
dyad
spectroscopy
polarity-dependent singlet oxygen production
2- C positions
SOCT-ISC mechanism