Journal of the American Chemical Society,
Journal Year:
2024,
Volume and Issue:
unknown
Published: Dec. 6, 2024
The
semiconductor
properties
of
nanosized
graphene
fragments,
known
as
molecular
nanographenes,
position
them
exceptional
candidates
for
next-generation
optoelectronics.
In
addition
to
their
remarkable
optical
and
electronic
features,
chiral
nanographenes
exhibit
high
dissymmetry
factors
in
circular
dichroism
circularly
polarized
luminescence
measurements.
However,
the
synthesis
enantiomerically
pure
remains
a
significant
challenge.
Typically,
these
materials
are
synthesized
racemic
form,
followed
by
separation
enantiomers
using
high-performance
liquid
chromatography
(HPLC).
While
effective,
this
method
often
requires
expensive
instrumentation,
extensive
optimization
conditions,
typically
yields
analytical
quantities
desired
samples.
An
alternative
approach
is
enantioselective
nanographenes;
however,
date,
only
two
examples
have
been
documented
literature.
work,
we
present
straightforward
chemical
resolution
helical
bilayer
nanographenes.
This
enables
effective
scalable
preparation
while
avoiding
need
HPLC.
incorporation
BINOL
core
into
polyarene
precursor
facilitates
diastereomers
through
esterification
with
camphorsulfonyl
chloride.
Following
standard
chromatographic
column,
hydrolysis
group
nanographene
precursors.
subsequent
graphitization,
achieved
Scholl
reaction,
occurs
an
enantiospecific
manner
concomitant
formation
furan
ring
heterohelicene
moiety.
absolute
configurations
final
enantiomers,
P-oxa[9]HBNG
M-oxa[9]HBNG,
determined
X-ray
diffraction.
Additionally,
electrochemical,
photophysical,
chiroptical
thoroughly
evaluated.
Chemistry - A European Journal,
Journal Year:
2024,
Volume and Issue:
30(41)
Published: May 16, 2024
Abstract
The
intramolecular
coupling
of
dichloro‐substituted
helically
fused
anthracenes
using
the
Yamamoto
yielded
cyclized
products
with
sterically
congested
molecular
structures.
X‐ray
analysis
and
DFT
calculations
showed
that
aromatic
framework
adopted
a
nonplanar
structure
twisted
conformation
about
newly
formed
single
bond,
which
acts
as
chiral
axis.
Interestingly,
obtained
through
Hirshfeld
atom
refinement
revealed
short
interatomic
distances
between
inner
hydrogen
atoms
(1.648–1.692
Å),
much
shorter
than
sum
their
van
der
Waals
radii.
Owing
to
these
unusually
contacts,
1
H
NMR
spectrum
exhibited
significant
deshielding
(12.5
ppm)
large
nuclear
Overhauser
effect
(44
%).
Additionally,
IR
displayed
high‐frequency
shift
C−H
stretching
vibration.
These
observations,
along
noncovalent
interaction
plot
indicative
characteristic
steric
environment,
strongly
support
presence
hindrance.
Moreover,
dynamic
measurement
mesityl‐substituted
derivative
barrier
helical
inversion
84
kJ
mol
−1
.
optical
properties
crystal
packing
are
also
reported.
Angewandte Chemie International Edition,
Journal Year:
2024,
Volume and Issue:
63(41)
Published: July 19, 2024
Abstract
The
introduction
of
precise
pore
defects
into
nanocarbon
structures
results
in
the
emergence
distinct
physicochemical
characteristics.
However,
there
is
a
lack
research
on
non‐planar
chiral
nanographene
involving
defects.
Herein,
we
have
developed
two
analogues
to
π‐extended
pentadecabenzo[9]helicene
(
EP9H
)
containing
embedded
Each
molecules,
namely
extended
dodecabenzo[7]helicene
ED7H
;
1
or
nonabenzo[5]helicene
EN5H
2
),
exhibits
dual‐state
emission.
Significantly,
value
|
g
lum
exceptionally
high
at
1.41×10
−2
solution
and
B
CPL
as
254
M
−1
cm
.
In
PMMA
film,
8.56×10
−3
,
powder
it
5.00×10
This
study
demonstrates
that
molecules
with
exhibit
emission
properties
while
maintaining
quite
good
luminescence
properties.
It
was
distinguished
from
aggregation‐caused
quenching
(ACQ)
effect
corresponding
without
defect.
Incorporating
also
simplifies
synthesis
process
enhances
solubility
resulting
product.
These
findings
suggest
can
be
viable
approach
improve
molecules.
Chemical Science,
Journal Year:
2025,
Volume and Issue:
unknown
Published: Jan. 1, 2025
Axially
chiral
substrates
were
transformed
into
enantiomer-enriched
π-extended
helicenes
via
a
chiral-transfer-based
Scholl
reaction,
and
enantiomers
efficiently
separated
without
labor-intensive
high-performance
liquid
chromatography
(HPLC).
Organic Letters,
Journal Year:
2025,
Volume and Issue:
unknown
Published: May 2, 2025
Double
[8]helicene
1,
featuring
a
dibenzo[g,p]chrysene
core,
was
synthesized
via
the
Scholl
reaction,
and
its
structure
unambiguously
confirmed
by
single-crystal
X-ray
diffraction
analysis
of
dicationic
salt
[1-Cl]2+·(SbCl6-)2.
The
compound
exhibits
red
fluorescence
with
an
emission
maximum
at
618
nm
(λem)
quantum
yield
16.2%,
highlighting
potential
in
optoelectronic
applications.
Furthermore,
circular
dichroism
(CD)
circularly
polarized
luminescence
(CPL)
measurements
reveal
notable
chiroptical
activity,
absorption
dissymmetry
factors
|gabs|
=
5.11
×
10-3
|glum|
7.1
10-4,
respectively.
Chemistry of Materials,
Journal Year:
2024,
Volume and Issue:
unknown
Published: Aug. 14, 2024
Molecular
topology
synthesis
of
polycyclic
aromatic
hydrocarbons
(PAHs)
with
diradical
character
takes
root
in
intramolecular
coupling
breakthrough.
Herein,
we
report
selective
Mn(III)/Cu(II)-mediated
C–P
and
C–H
bond
cleavage
to
obtain
robust
donor-fused
phosphoniums
helical
or
planar
geometries
distinct
cationic
charges.
The
former
structures
incorporate
a
common
phospha[5]helication
acceptor
different
arylamine
donors,
the
latter
structure
contains
phospha[6]dication
same
donors.
These
unprecedented
ionic
salts
hold
distinguishing
donor–acceptor
(D–A)
constructions,
showing
unique
topology-dependent
optoelectronic
properties.
folded
radical
ammoniums
possess
an
extreme
electron-deficient
state
through-space
isolation
high
(y0
=
0.989).
Moreover,
tunable
charge
transfer
(CT)
locally
excited
(LE)
transition
components
facilitate
diverse
hybridized
local
(HLCT)
solvents,
endowing
highest
emission
band
gap
variation
0.78
eV
(∼217
nm).
fluorescence
radiation
could
also
be
adjusted
from
blue
near-infrared
regions
via
tailoring
polar-dependent
states,
which
output
additional
circularly
polarized
luminescence
compatible
chiral
menthol
matrix
elevated
quantum
efficiency
undisturbed
deep-red
glow.
It
is
worth
mentioning
that
atomically
precise
Mn(III)
halide
has
been
unprecedentedly
captured
determined
for
activation.
The Journal of Organic Chemistry,
Journal Year:
2023,
Volume and Issue:
89(1), P. 498 - 504
Published: Dec. 22, 2023
Recently,
the
synthesis
of
racemate
an
overcrowded
triply
fused
carbo[7]helicene
formula
C66H36
with
three
carbo[7]helicenes
within
a
central
six-membered
ring
was
described.
This
molecule
found
to
embed
extremely
contorted
and
two
negative
curvatures.
We
report
herein
resolution
corresponding
enantiomers
their
conformational,
structural,
photophysical,
chiroptical
properties.
The
racemization
determined
proceed
at
rate
krac
=
8.06
×
10–4
s–1
175
°C
in
ortho-dichlorobenzene,
barrier
enantiomerization
ΔGenant‡
140.4
kJ·mol–1,
value
significantly
lower
than
for
pristine
carbo[7]helicene.
Interestingly,
crystalline
structures
racemic
enantiopure
materials
show
some
differences
regarding
molecular
geometry,
increased
curvature
latter
cases.
unusual
curved
delocalized
π-conjugated
system
afforded
notably
green
fluorescence
room
temperature
far-red
phosphorescence
low
temperature.
Finally,
electronic
circular
dichroism
circularly
polarized
luminescence
responses
compounds
have
been
measured
showed
very
close
absorption
emission
dissymmetry
factors,
gabs
glum,
respectively,
ca.
2.6
10–3,
indicating
similar
chiral
rigid
geometry
both
ground
excited
states.
Chemistry - A European Journal,
Journal Year:
2024,
Volume and Issue:
unknown
Published: Dec. 12, 2024
Helical
fused
anthracenes
were
elongated
by
fusing
additional
aromatic
units
at
both
ends
to
yield
novel
expanded
helicenes.
Compounds
[5]HA2N
and
[7]HA
consisting
of
19
21
benzene
rings,
respectively,
synthesized
fourfold
cycloisomerization
the
corresponding
terminal
alkyne
precursors.
The
helical
structures
confirmed
X-ray
crystallographic
analysis,
where
frameworks
stacked
effectively
with
turn
numbers
exceeding
two.
enantiomers
two
compounds
resolved
chiral
HPLC.
Whereas
readily
underwent
enantiomerization
room
temperature
barrier
91
kJ
mol
Asian Journal of Organic Chemistry,
Journal Year:
2024,
Volume and Issue:
13(7)
Published: May 9, 2024
Abstract
Aza[6]helicene
and
aza[7]helicene
were
synthesized
by
Fridel‐Crafts‐type
cyclization
of
axially
chiral
compounds.
From
the
compounds
prepared
Fischer
indole
synthesis,
aza[6]helicene
synthesized.
Aza[7]helicene
was
also
from
an
pyrrole
compound
Piloty‐Robinson‐type
synthesis
through
simultaneous
on
both
sides
ring.
isomerized
readily
at
room
temperature,
while
isomerization
temperature
less
likely
to
proceed.
The
cell
growth
inhibitory
activity
each
enantiomer
N
‐Me‐aza[7]helicene
in
HeLa
cells
examined.
Differences
strength
between
enantiomers
observed.
Angewandte Chemie,
Journal Year:
2024,
Volume and Issue:
136(41)
Published: July 19, 2024
Abstract
The
introduction
of
precise
pore
defects
into
nanocarbon
structures
results
in
the
emergence
distinct
physicochemical
characteristics.
However,
there
is
a
lack
research
on
non‐planar
chiral
nanographene
involving
defects.
Herein,
we
have
developed
two
analogues
to
π‐extended
pentadecabenzo[9]helicene
(
EP9H
)
containing
embedded
Each
molecules,
namely
extended
dodecabenzo[7]helicene
ED7H
;
1
or
nonabenzo[5]helicene
EN5H
2
),
exhibits
dual‐state
emission.
Significantly,
value
|
g
lum
exceptionally
high
at
1.41×10
−2
solution
and
B
CPL
as
254
M
−1
cm
.
In
PMMA
film,
8.56×10
−3
,
powder
it
5.00×10
This
study
demonstrates
that
molecules
with
exhibit
emission
properties
while
maintaining
quite
good
luminescence
properties.
It
was
distinguished
from
aggregation‐caused
quenching
(ACQ)
effect
corresponding
without
defect.
Incorporating
also
simplifies
synthesis
process
enhances
solubility
resulting
product.
These
findings
suggest
can
be
viable
approach
improve
molecules.
