Angewandte Chemie,
Journal Year:
2024,
Volume and Issue:
unknown
Published: Nov. 18, 2024
Abstract
The
synthesis
and
stabilization
of
heteroatom‐doped
nanocarbon
molecules,
such
as
carbazole‐containing
(super)helicenes,
present
significant
challenges
due
to
the
complexities
involved
in
maintaining
structural
integrity
electronic
functionality.
In
this
study,
we
successfully
synthesized
a
carbazole‐centered
expanded
tris‐hexabenzo[7]helicene
(
1
)
via
facile
FeCl
3
‐mediated
Scholl
coupling
reaction.
exhibits
both
chemical
chiral
stability
demonstrates
fluorescence
at
628
nm
with
quantum
yield
0.40.
Additionally,
enantiomers
display
pronounced
chiroptical
properties,
including
distinct
circular
dichroism
(CD)
signal
spanning
from
300
600
nm.
absorption
dissymmetry
factor
(|
g
abs
|)
is
determined
be
2.98×10
−3
,
while
circularly
polarized
luminescence
brightness
B
CPL
measured
32.50
M
−1
cm
.
Advanced Materials,
Journal Year:
2023,
Volume and Issue:
36(5)
Published: Sept. 12, 2023
Chiral
B/N
embedded
multi-resonance
(MR)
emitters
open
a
new
paradigm
of
circularly
polarized
(CP)
organic
light-emitting
diodes
(OLEDs)
owing
to
their
unique
narrowband
spectra.
However,
pure-red
CP-MR
and
devices
remain
exclusive
in
literature.
Herein,
by
introducing
B-N
covalent
bond
lower
the
electron-withdrawing
ability
para-positioned
B-π-B
motif,
first
pair
double
hetero-[n]helicenes
(n
=
6
7)
emitter
peaking
617
nm
with
small
full-width
at
half-maximum
38
high
photoluminescence
quantum
yield
≈100%
toluene
is
developed.
The
intense
mirror-image
CP
light
produced
enantiomers
characterized
dissymmetry
factors
(g
Journal of the American Chemical Society,
Journal Year:
2024,
Volume and Issue:
146(23), P. 16161 - 16172
Published: May 9, 2024
Introducing
helical
subunits
into
negatively
curved
π-systems
has
a
significant
effect
on
both
the
molecular
geometry
and
photophysical
properties;
however,
synthesis
of
these
embedded
with
nonbenzenoid
remains
challenging
due
to
high
strain
deriving
from
curvature
helix.
Here,
we
report
family
nonalternant
nanographenes
containing
nitrogen
(N)-doped
cyclopenta[ef]heptalene
unit.
Among
them,
CPH-2
CPH-3
can
be
viewed
as
hybrids
benzoannulated
aza[7]helicene.
The
crystal
structures
revealed
saddle
for
CPH-1,
saddle-helix
hybrid
CPH-2,
twist-helix
CPH-3.
Experimental
measurements
theoretical
calculations
indicate
that
moieties
in
CPHs
undergo
flexible
conformational
changes
at
room
temperature,
while
aza[7]helicene
subunit
exhibits
dramatically
increased
racemization
energy
barrier
(78.2
kcal
mol–1
143.2
CPH-3).
combination
lone
electron
pairs
N-doped
unit
twisted
helix
fragments
results
rich
photophysics
distinctive
fluorescence
phosphorescence
CPH-1
similar
Both
enantiopure
display
distinct
circular
dichroism
(CD)
signals
UV–vis
range.
Notably,
compared
reported
fully
π-extended
nanographenes,
excellent
chiroptical
properties
|gabs|
value
1.0
×
10–2
|glum|
7.0
10–3;
values
are
among
highest
nanographenes.
Angewandte Chemie International Edition,
Journal Year:
2024,
Volume and Issue:
63(27)
Published: Feb. 27, 2024
π-Conjugated
chiral
nanorings
with
intriguing
electronic
structures
and
chiroptical
properties
have
attracted
considerable
interests
in
synthetic
chemistry
materials
science.
We
present
the
design
principles
to
access
new
macrocycles
(1
2)
that
are
essentially
built
on
key
components
of
main-group
electron-donating
carbazolyl
moieties
or
π-expanded
aza[7]helicenes.
Both
show
unique
molecular
conformations
a
(quasi)
figure-of-eight
topology
as
result
conjugation
patterns
2,2',7,7'-spirobifluorenyl
1
triarylamine-coupled
aza[7]helicene-based
building
blocks
2.
This
nature
redox-active,
carbazole-rich
backbones
enabled
these
be
readily
oxidized
chemically
electrochemically,
leading
sequential
production
series
positively
charged
polycationic
open-shell
cyclophanes.
Their
redox-dependent
states
resulting
multispin
polyradicals
been
characterized
by
VT-ESR,
UV/Vis-NIR
absorption
spectroelectrochemical
measurements.
The
singlet
(ΔE
Advanced Functional Materials,
Journal Year:
2024,
Volume and Issue:
34(21)
Published: Jan. 29, 2024
Abstract
Organic
radical
luminescent
materials
have
attracted
worldwide
attention
because
of
their
absolute
spin‐allowed
radiative
transition
and
sensitivity
to
the
environment,
which
give
it
multiple
stimulus
response
properties.
Nowadays,
how
regulate
utilize
radicals
has
become
a
hot
difficult
issue.
Here,
arylphosphonium
bromide
salts
are
introduced
into
molecular
backbone
naphthimide
(
NMI
)
using
an
intramolecular
counterion
strategy,
prepared
novel
multifunctional
stabilized
luminescent:
TPP‐
o
‐3OMe‐NMI‐Br
.
Interestingly,
this
molecule
exhibits
different
assembly
modes
in
solvents,
resulting
generation
two
crystals
with
fluorescence
(green:
G‐C;
orange–yellow:
Y‐C),
Y‐C
crystalline
powder
excellent
stabilization
properties
for
doublet
triplet
excitons,
induce
emission
orange–yellow
afterglow,
multi‐stimuli
responsiveness
external
pressure
(P),
temperature
(T)
water
(W).
Moreover,
interesting
time‐dependent
photoactivated
colorful
afterglow
can
be
observed
‐3OMe‐NMI‐Br@PMMA
films
doping
ratios
exhibit
multi‐color
tunability,
responses,
data
encryption,
optical
information
erase/write
behavior.
This
study
not
only
broadens
types
applications
organic
long
but
also
provides
new
ideas
designing
“chameleon”
field
smart
luminescence
materials.
Journal of the American Chemical Society,
Journal Year:
2024,
Volume and Issue:
146(13), P. 9422 - 9433
Published: March 19, 2024
We
report
a
neutral
high-spin
diradical
of
chiral
C2-symmetric
bis[5]diazahelicene
with
ΔEST
≈
0.4
kcal
mol–1,
as
determined
by
EPR
spectroscopy/SQUID
magnetometry.
The
is
the
most
persistent
among
all
aminyl
radicals
reported
to
date
factor
20,
half-life
up
6
days
in
2-MeTHF
at
room
temperature.
Its
triplet
ground
state
and
excellent
persistence
may
be
associated
unique
spin
density
distribution
within
dihydrophenazine
moiety,
which
characterizes
two
effective
3-electron
C–N
bonds
analogous
N–O
bond
nitroxide
radical.
enantiomerically
enriched
(ee
≥
94%)
(MM)-
(PP)-enantiomers
precursors
diradicals
are
obtained
either
preparative
supercritical
fluid
chromatography
or
resolution
via
functionalization
auxiliary
racemic
tetraamine.
barrier
for
racemization
solid
tetraamine
ΔG‡
=
43
±
0.01
mol–1
483–523
K
range.
experimentally
estimated
lower
limit
diradical,
26
293
K,
comparable
DFT-determined
31
gas
phase
298
K.
While
pure
displays
strong
chiroptical
properties,
anisotropy
|g|
|Δε|/ε
0.036
376
nm,
0.005
548
nm
that
recently
ground-state
dication.
Notably,
radical
anion
intermediate
generation
exhibits
large
SOMO-HOMO
inversion,
SHI
35
mol–1.
Journal of the American Chemical Society,
Journal Year:
2024,
Volume and Issue:
146(28), P. 19168 - 19176
Published: July 2, 2024
Molecular
switches
have
received
major
attention
to
enable
the
reversible
modulation
of
various
molecular
properties
and
been
extensively
used
as
trigger
elements
in
diverse
fields,
including
machines,
responsive
materials,
photopharmacology.
Antiaromaticity
is
a
fascinating
property
that
has
attracted
not
only
significant
fundamental
interest
but
also
increasingly
relevant
different
applications,
particular
organic
(opto)electronics.
However,
designing
systems
which
(anti)aromaticity
can
be
judiciously
reversibly
switched
ON
OFF
remains
challenging.
Herein,
we
report
helicene
featuring
an
indenofluorene-bridged
bisthioxanthylidene
novel
switch
wherein
simultaneous
two-electron
(electro)chemical
redox
process
allows
highly
its
(anti)aromatic
character.
Specifically,
two
thioxanthylidene
rotors,
attached
initially
aromatic
indenofluorene
scaffold
via
overcrowded
alkenes,
adopt
anti-folded
structure,
upon
oxidation
convert
singly
bonded,
twisted
conformations.
This
associated
with
(chir)optical
changes
importantly
results
formation
fully
conjugated,
formally
antiaromatic
as-indacene
motif
helical
core
switch.
proceeds
without
buildup
radical
cation
intermediates
thus
enables
switching
geometry,
aromaticity,
absorbance,
chiral
expression
under
ambient
conditions,
evidenced
by
NMR,
UV–vis,
CD,
(spectro)electrochemical
analyses,
supported
DFT
calculations.
We
expect
this
concept
extendable
wide
range
robust
antiaromatic–aromatic
provide
basis
for
structure
these
inherently
polycyclic
π-scaffolds.
Journal of the American Chemical Society,
Journal Year:
2024,
Volume and Issue:
146(12), P. 8308 - 8319
Published: March 14, 2024
Modulation
of
absorbance
and
emission
is
key
for
the
design
chiral
chromophores.
Accessing
a
series
compounds
absorbing
emitting
(circularly
polarized)
light
over
wide
spectral
window
often
toward
near-infrared
practical
value
in
(chir)optical
applications.
Herein,
by
late-stage
functionalization
on
derivatives
bridging
triaryl
methyl
helicene
domains,
we
have
achieved
regioselective
triple
introduction
para
electron-donating
or
electron-withdrawing
substituents.
Extended
tuning
electronic
(e.g.,
E1/2red
−1.50
V
→
−0.68
V)
optical
covering
from
550
to
850
nm)
properties
cations
neutral
radicals;
latter
being
easily
prepared
mono
electron
reductions
under
electrochemical
chemical
conditions.
While
luminescence
quantum
yields
can
be
increased
up
70%
cationic
series,
strong
Cotton
effects
are
obtained
certain
radicals
at
low
energies
(λabs
∼
700–900
with
gabs
values
above
10–3.
The
open-shell
nature
was
further
characterized
paramagnetic
resonance
revealing
an
important
spin
density
delocalization
that
contributes
their
persistence.
Angewandte Chemie International Edition,
Journal Year:
2024,
Volume and Issue:
63(45)
Published: Aug. 8, 2024
Doping
of
polycyclic
conjugated
hydrocarbons
(PCHs)
with
sulfur
atoms
is
becoming
more
and
important
as
a
means
creating
unique
functional
materials.
Recently,
thiophene-containing
multiple
helicenes
have
garnered
enormous
attention
due
to
their
intriguing
electronic
(chir)optical
properties
compared
carbohelicenes.
However,
the
efficient
synthesis
thiopyran-containing
underlying
doping
mechanisms
are
rather
unexplored.
Herein,
structural
analysis
double
[7]helicene
3
reported.
X-ray
crystallographic
reveals
its
dication
C
