Journal of the American Chemical Society,
Год журнала:
2024,
Номер
146(13), С. 9422 - 9433
Опубликована: Март 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.
Angewandte Chemie International Edition,
Год журнала:
2023,
Номер
62(18)
Опубликована: Март 6, 2023
We
herein
present
the
synthetic
approach
to
a
new
antiaromatic
double
aza[7]helicene
C
that
features
NN-embedded
polycyclic
aromatic
hydrocarbons
(PAHs).
This
heteroatom-doped
helicene
showed
rarely
obtained
long-wavelength
emission
and
far-red
circularly
polarized
luminescence
(CPL)
in
solid
state.
These
optical
chiroptical
properties
could
be
ascribed
both
NN-PAH
core
structure
further
extension
through
angular
ring
fusions.
Such
unique
electronic
also
culminated
facile
chemical
oxidations
of
neutral
positively
charged
chiral
radical
(C⋅+
)
dication
species
(C2+
).
Interestingly,
DFT
computations
revealed
pyridazine
central
an
antiaromaticity-to-aromaticity
switching,
contrast
inversed
transition
for
helical
periphery
cationic
states.
The
reported
approaches
are
anticipated
lead
development
redox-active
systems
potential
applications
chiroptoelectronics,
spintronics
as
well
fluorescent
bioimaging.
Angewandte Chemie International Edition,
Год журнала:
2023,
Номер
62(38)
Опубликована: Авг. 3, 2023
Efficient
circularly
polarized
luminescence
(CPL)
from
purely
organic
molecules
holds
great
promise
for
applications
in
displays,
sensing,
and
bioimaging.
However,
achieving
high
dissymmetry
values
(glum
)
chromophores
remains
a
significant
challenge.
Herein,
we
present
bioinspired
approach
using
adenosine
triphosphate
(ATP)-triggered
supramolecular
polymerization
of
naphthalene
diimide-derived
monomer
(ANSG)
to
induce
CPL
with
remarkable
glum
value
1.1×10-2
.
The
ANSG
undergo
templated,
chiral
self-assembly
through
cooperative
growth
mechanism
the
presence
ATP,
resulting
scrolled
nanotubes
aggregation-induced
enhanced
emission
(AIEE)
induced
CPL.
Furthermore,
demonstrate
concept
chiroptical
amplification
by
efficiently
amplifying
asymmetry
mixture
ATP
achiral
pyrophosphate.
This
innovative
opens
numerous
opportunities
emerging
field
luminescence.
Journal of the American Chemical Society,
Год журнала:
2023,
Номер
145(49), С. 26824 - 26832
Опубликована: Дек. 4, 2023
Helical
nanographenes
(NGs)
have
attracted
increasing
attention
recently
because
of
their
intrinsic
chirality
and
exotic
chiroptical
properties.
However,
the
efficient
synthesis
extended
helical
NGs
featuring
a
multilayer
topology
is
still
underdeveloped,
layer-dependent
properties
remain
elusive.
In
this
study,
we
demonstrate
modular
synthetic
strategy
to
construct
series
novel
(1-3)
with
through
consecutive
Diels-Alder
reaction
regioselective
cyclodehydrogenation
from
readily
accessible
phenanthrene-based
precursors
bearing
ethynyl
groups.
The
resultant
exhibit
bilayer,
trilayer,
tetralayer
structures
elongated
π
extension
rigid
backbones,
as
unambiguously
confirmed
by
single-crystal
X-ray
or
electron
diffraction
analysis.
We
find
that
photophysical
these
are
notably
influenced
degree
extension,
which
varies
number
layers,
leading
obvious
redshifted
absorption,
fast
rising
molar
extinction
coefficient
(ε),
markedly
boosted
fluorescence
quantum
yield
(Φf).
Moreover,
embedded
[7]helicene
subunits
in
result
stable
chirality,
enabling
both
chiral
resolution
exploration
Profiting
good
alignment
electric
magnetic
dipole
moments
determined
structure,
excellent
circular
dichroism
circularly
polarized
luminescence
response
unprecedented
high
CPL
brightness
up
168
M-1
cm-1,
rendering
them
promising
candidates
for
emitters.
Journal of the American Chemical Society,
Год журнала:
2024,
Номер
146(25), С. 17428 - 17437
Опубликована: Июнь 12, 2024
Synthetic
challenges
toward
anomalous
structures
and
electronic
states
often
involve
handling
problems
such
as
insolubility
in
common
organic
solvents
oxidative
degradation
under
aerobic
conditions.
We
designed
benzo-annulated
aza[n]helicenes,
which
benefit
from
both
the
suppressed
elevation
of
highest
occupied
molecular
orbital
(HOMO)
energies
high
solubility
due
to
hydrogen
bonding
with
solvent
molecules
overcome
these
challenges.
This
strategy
enabled
synthesis
six
new
aza[n]helicenes
([n]AHs)
different
lengths
(n
=
9–19)
acyclic
precursors
via
one-pot
intramolecular
fusion
reactions.
The
all
synthesized
were
determined
by
X-ray
diffraction
(XRD)
analysis,
their
electrochemical
potentials
measured
cyclic
voltammetry.
Among
[17]AH
[19]AH
are
first
heterohelicenes
a
triple-layered
helix.
noncovalent
interaction
(NCI)
plots
confirm
existence
an
effective
π–π
between
layers.
absorption
fluorescence
spectra
red-shifted
helical
increased,
without
any
distinct
saturation
points.
optical
resolutions
N-butylated
[9]AH,
[11]AH,
[13]AH,
[15]AH
accomplished,
circular
dichroism
(CD)
circularly
polarized
luminescence
(CPL)
measured.
Thus,
structural,
(chir)optical,
properties
comprehensively
analyzed.
Angewandte Chemie International Edition,
Год журнала:
2024,
Номер
63(19)
Опубликована: Фев. 19, 2024
Helical
nanographenes
with
high
quantum
yields
and
strong
chiroptical
responses
are
pivotal
for
developing
circularly
polarized
luminescence
(CPL)
materials.
Here,
we
present
the
successful
synthesis
of
novel
π-extended
double
[7]helicenes
(ED7Hs)
where
two
helicene
units
fused
at
meta-
or
para-position
middle
benzene
ring,
respectively,
as
structural
isomers
reported
ortho-fused
ED7H.
The
geometry
these
ED7Hs
is
clearly
characterized
by
single-crystal
X-ray
analysis.
Notably,
this
class
exhibits
bright
exceeding
40
%.
Through
geometric
regulation
embedded
[7]helicene
from
ortho-,
to
para-position,
display
exceptional
amplification
in
responses.
This
enhancement
evident
a
remarkable
approximate
fivefold
increase
absorbance
dissymmetry
factors
(g
National Science Review,
Год журнала:
2024,
Номер
11(9)
Опубликована: Июнь 20, 2024
This
review
discusses
opportunities
in
chemistry
that
are
enabled
by
the
chiral
induced
spin
selectivity
(CISS)
effect.
First,
begins
with
a
brief
overview
of
seminal
studies
on
CISS.
Next,
we
discuss
different
material
systems
whose
properties
can
be
tailored
through
chemical
means,
special
emphasis
hybrid
organic-inorganic
layered
materials
exhibit
some
largest
filtering
to
date.
Then,
promise
CISS
for
reactions
and
enantioseparation
before
concluding.
Advanced Optical Materials,
Год журнала:
2025,
Номер
unknown
Опубликована: Янв. 30, 2025
Abstract
Establishing
design
principles
to
engineer
molecules
that
exhibit
strong
circularly
polarized
luminescence
(CPL)‐brightness
across
the
UV,
visible
and
NIR
spectral
range
remains
an
unsolved
challenge.
To
achieve
a
large
CPL‐brightness,
main
difficulty
is
optimize
dissymmetry
factor
g
lum
.
Herein
described
discovery
multi‐helicene
system
based
on
series
of
annulated
[6]helicenes
perylenediimides,
exhibits
larger‐than‐linear
amplification
with
helicene
length.
Large
enhanced
fluorescent
quantum
yields
extinction
coefficients
are
also
observed
for
this
length
series.
Consequently,
oligomers
exceptional
CPL
brightness
(B
)
above
1
×
10
3
mol
−1
cm
Using
computational
methods
density
functional
theory
(DFT),
experimental
trend
shows
increase
glum
due
progressive
alignment
magnetic
(|m|)
electric
transition
(|µ|)
dipole
moment
vectors,
as
helical
backbone
grows
longer.
Chemical Science,
Год журнала:
2022,
Номер
14(3), С. 491 - 498
Опубликована: Ноя. 28, 2022
Since
the
observation
of
chirality
at
nanoscale,
research
focused
towards
design
and
synthesis
optically
active
nanomaterials
has
been
a
brisk
pace.
In
this
regard,
carbon
based
zero
dimensional
have
attracted
vast
attention
due
to
their
rich
optical
properties,
abundance
raw
materials,
minimal
environmental
hazardousness,
good
solubility,
ease
surface
modification.
However,
efforts
chiral
nanodots
exhibiting
activity
both
in
ground
excited
states
are
rather
scarce.
Herein,
we
report
facile
synthetic
approach
for
preparation
three
sets
intrinsically
that
exhibit
intense
circularly
polarized
luminescence.
Synthesis
under
optimized
conditions
using
l-
d-isomers
precursors
led
formation
displayed
mirror
image
circular
dichroism
luminescence
signals
revealing
state
chirality.
The
experimental
results
supportive
reported
core-shell
model
comprising
an
achiral
core
is
enclosed
within
amorphous
shell
contributing
anisotropy
wavelength
could
be
tuned
by
varying
such
as
temperature
pH.
emissive
properties
nanoparticles
demonstrated
free-standing
polymeric
films
potential
used
light
emitting
agents
devices,
data
storage
security
tags.
Being
first
intrinsic
from
range
nanodots,
solution
solid
state,
envisage
work
will
open
new
avenues
investigation
stated
nanoscale.
Advanced Materials,
Год журнала:
2022,
Номер
35(8)
Опубликована: Дек. 8, 2022
It
is
well-known
that
high-performance
circularly
polarized
organic
light-emitting
diodes
(CP-OLEDs)
remain
a
formidable
challenge
to
the
future
application
of
luminescent
(CPL)-active
materials.
Herein,
design
pair
AIE-active
chiral
enantiomers
(L/D-HP)
described
construct
co-assemblies
with
an
achiral
naphthalimide
dye
(NTi).
The
resulting
emit
inverted
CPL
signal
compared
from
L/D-HP
enantiomers.
After
thermal
annealing
at
120
°C,
this
kind
L/D-HP-NTi
1:1
molar
ratio
shows
regular
and
ordered
helical
nanofibers
arranged
through
intermolecularly
layered
packing
accompanied
further
amplified
effect
(|gem
|
=
0.032,
λem
535
nm).
Significantly,
non-doped
CP-OLEDs
based
on
device
emitting
layer
(EML)
exhibits
low
turn-on
voltage
(Von
)
4.7
V,
high
maximum
brightness
(Lmax
2001
cd
m-2
,
moderate
external
quantum
efficiency
(EQEmax
2.3%,
as
well
excellent
electroluminescence
(CP-EL)
(|gEL
0.023,
533