Eight-membered cyclic and [5,5]-bicyclic
sulfides were synthesized
via a domino reaction between thioaurone analogues and arynes. Density
functional theory calculations were performed to elucidate the reaction
mechanism, which involves the elementary steps of the [3 + 2] cycloaddition,
1,2-hydrogen shift, and C(sp2)–S bond cleavage as
well as the substituent effect.
Density functional
calculations at the B3LYP-D3+IDSCRF/TZP-DKH(-dfg)
level of theory have been performed to understand the mechanism of
ruthenium-catalyzed C–H allylation reported in the literature
in depth. The plausible pathway consisted of four sequential processes,
including C–H activation, migratory insertion, amide extrusion,
and recovery of the catalyst, in which C–H activation was identified
as the rate-determining step. The amide extrusion step could be promoted
kinetically by trifluoroacetic acid since its mediation lowered the
free-energy barrier from 32.1 to 12.2 kcal/mol. Additional calculations
have been performed to explore other common pathways between arenes
and alkenes, such as C–H alkenylation and hydroarylation. A
comparison of the amide extrusion and β-H elimination steps
established the following reactivity sequence of the leaving groups:
protonated amide group > β-H group > unprotonated amide
group.
The suppression of hydroarylation was attributed to the sluggishness
of the Ru–C protonation step as compared to the amide extrusion
step. This study can unveil factors favoring the C–H allylation
reaction.
High-performance heterojunction organic photodetectors
(OPDs) are
of great significance in optical detecting technology due to their
tailorable optoelectronic properties. Herein, we designed and synthesized
three n-type subphthalocyanine (SubPc) derivatives PhO-BSubPcF12, CHO-PhO-BSubPcF12, and NO2-PhO-BSubPcF12 via axial nonhalogen substitution on fluorinated SubPc.
These SubPc derivatives exhibit improved intramolecular charge transfer,
high electron mobilities, optimized energy levels, and good thermal
stability. The novel isotype p–n SubPc heterojunctions are
evaluated as photosensitive layers in OPDs, which show a UV–visible
dual-band response and self-powered effect. The optimal OPD with Br-BSubPc/NO2-PhO-BSubPcF12 presents stable and superior performances
with a high responsivity (R) of 0.14 A W–1, a peak external quantum efficiency (EQE) of 30.6%, and an extremely
low dark current of 0.92 nA cm–2 under a 570–595
nm illumination without a bias voltage. It has outperformed most of
the reported SubPc-based OPDs. The better interfacial contact of p–n
SubPc derivatives leads to a large depletion region with decreased
trap densities as well as a low carrier recombination rate, which
is conducive to the photoinduced carriers’ separation and well-balanced
transport, resulting in high device performances. Moreover, a secure
communication strategy is successfully demonstrated by dual-band optimal
OPD. This work is expected to provide some guidance for molecular
engineering and device performance toward multifunctional electronics.
The exploration of new reactivity modes and synthetic methods has always been an attractive goal of organic and medicinal chemistry. As potential raw materials for the efficient construction of nitrogen-...
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