Organic Letters,
Год журнала:
2024,
Номер
26(44), С. 9486 - 9491
Опубликована: Окт. 28, 2024
Three
novel
azatwistarenes
5a,
8,
and
13
have
been
synthesized
via
the
Povarov
reaction
fully
characterized.
All
of
enantiomers
were
separated
using
chiral
high-performance
liquid
chromatography,
their
optical
properties
investigated
through
circular
dichroism
circularly
polarized
luminescence
spectra.
In
addition,
such
desired
a
positive
response
to
acid
in
dichloromethane.
Journal of the American Chemical Society,
Год журнала:
2024,
Номер
146(23), С. 16161 - 16172
Опубликована: Май 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.
Precision Chemistry,
Год журнала:
2024,
Номер
2(9), С. 488 - 494
Опубликована: Авг. 13, 2024
Multiple
helicenes
display
distinct
aromatic
cores
characterized
by
highly
twisted
rings
that
are
shared
or
fused
with
constituent
helicene
moieties.
Diversifying
these
unlocks
avenues
for
creating
multiple
properties
and
topologies.
Herein
we
report
the
synthesis
of
a
quadruple[6]helicene
featuring
pyrene
as
core.
The
involved
key
steps
annulative
π-extension
reaction
Scholl
reaction.
By
extending
along
axial
direction,
degree
contortion
core
can
be
controlled
from
nearly
flat
to
twisted.
Notably,
exhibits
significant
red-shift
0.49
eV
compared
quadruple[4]helicenes,
which
arises
both
augmented
effective
conjugation
due
enhanced
twisting.
Quantum
chemical
calculations
demonstrate
in
adeptly
governs
energy
levels
HOMO
LUMO,
offers
an
alternative
strategy
beyond
mere
enlargement
π
backbone.
An
intriguing
serendipitous
finding
reveals
formation
one-molecule-thick
supramolecular
homochiral
nanosheets
through
self-interlocking
interactions
enantiomers
single
crystals,
rare
packing
motif
helicenes.
Angewandte Chemie International Edition,
Год журнала:
2024,
Номер
unknown
Опубликована: Окт. 31, 2024
Herein,
corannulene-based
quintuple
[6]helicenes
(Q[6]H-1
and
Q[6]H-2)
[7]helicene
(Q[7]H)
were
synthesized
via
penta-fold
Heck
Mallory
reaction.
Notably,
Q[7]H
represents
the
highest
reported
helicene
based
on
corannulene.
X-ray
crystallography
reveals
that
Q[6]H-2
adopts
a
propeller-shaped
conformation
with
well-preserved
corannulene
core,
while
Q[6]H-1
exhibit
quasi-propeller-shaped
conformations.
Upon
heating,
conformer
undergoes
conversion
to
thermodynamically
more
stable
Q[6]H-2,
whereas
remains
unchanged
due
larger
steric
congestion.
Racemization
of
enantiomer
conformational
observed
simultaneously
at
elevated
temperature,
DFT
studies
indicating
racemization
barrier
32.06
kcal
⋅
mol
A
quadruple
helicene
with
a
cyclooctatetrapyrrole
core
was
synthesized
via
simple
Ullmann
reaction.
Its
single-crystal
structure
exhibits
saddle
shape.
The
compound
shows
fluorescence
emission
λem
=
575
nm
and
good
chiroptical
properties,
including
dissymmetric
absorption
factor
(|gabs|)
of
5.84
×
10–3
(|glum|)
1.21
10–2.
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.
Angewandte Chemie International Edition,
Год журнала:
2024,
Номер
unknown
Опубликована: Июль 19, 2024
Abstract
Heteroatom‐embedded
helical
nanographenes
(NGs)
constitute
an
important
and
appealing
class
of
intrinsically
chiral
materials.
In
this
work,
a
series
B,N‐embedded
NGs
(BN‐HNGs)
bearing
azepines
was
synthesized
via
stepwise
regioselective
cyclodehydrogenation.
First,
the
phenyl‐
or
nitrogen‐bridged
dimers
were
efficiently
clipped
into
highly
congested
model
compounds
1
2
.
Later,
controllable
Scholl
reactions
tetraphenyl‐tethered
precursor
generated
1,
7
8
new
C−C
bonds,
thereby
establishing
robust
method
for
preparation
nonalternant
BN‐HNGs
with
up
to
31
fused
rings.
The
bilayer
nature
unambiguously
verified
by
X‐ray
diffraction
analysis.
chirality
transferred
stereogenic
boron
centers
upon
fluoride
coordination,
concave‐concave
structure
comply
skeleton.
Notably,
largest
BN‐HNG
(
6
)
spontaneously
resolved
homochiral
4
helix
as
molecular
spiral
staircase
during
crystallization
conglomerate
formation
at
single‐crystal
scale.
large
twisted
C
‐symmetric
π‐surface
dynamic
skeleton
induced
curved
might
have
synergistic
effects
on
self‐recognition
enantiomers
achieve
intriguing
spontaneous
resolution
behavior.
chiroptical
properties
enantiomer
further
investigated,
revealing
that
had
strong
response
in
visible
range
(400–700
nm).
Angewandte Chemie,
Год журнала:
2024,
Номер
136(42)
Опубликована: Июль 19, 2024
Abstract
Heteroatom‐embedded
helical
nanographenes
(NGs)
constitute
an
important
and
appealing
class
of
intrinsically
chiral
materials.
In
this
work,
a
series
B,N‐embedded
NGs
(BN‐HNGs)
bearing
azepines
was
synthesized
via
stepwise
regioselective
cyclodehydrogenation.
First,
the
phenyl‐
or
nitrogen‐bridged
dimers
were
efficiently
clipped
into
highly
congested
model
compounds
1
2
.
Later,
controllable
Scholl
reactions
tetraphenyl‐tethered
precursor
generated
1,
7
8
new
C−C
bonds,
thereby
establishing
robust
method
for
preparation
nonalternant
BN‐HNGs
with
up
to
31
fused
rings.
The
bilayer
nature
unambiguously
verified
by
X‐ray
diffraction
analysis.
chirality
transferred
stereogenic
boron
centers
upon
fluoride
coordination,
concave‐concave
structure
comply
skeleton.
Notably,
largest
BN‐HNG
(
6
)
spontaneously
resolved
homochiral
4
helix
as
molecular
spiral
staircase
during
crystallization
conglomerate
formation
at
single‐crystal
scale.
large
twisted
C
‐symmetric
π‐surface
dynamic
skeleton
induced
curved
might
have
synergistic
effects
on
self‐recognition
enantiomers
achieve
intriguing
spontaneous
resolution
behavior.
chiroptical
properties
enantiomer
further
investigated,
revealing
that
had
strong
response
in
visible
range
(400–700
nm).
Angewandte Chemie International Edition,
Год журнала:
2024,
Номер
unknown
Опубликована: Июль 20, 2024
Abstract
Introduction
of
non‐hexagons
and/or
heteroatoms
allows
for
finely
tuning
the
physicochemical
properties
nanographenes.
Heteroatoms
doping
have
dominated
modulation
nanographenes
with
tunable
band
gap,
rich
electrochemical
activities
and
so
on.
The
pair
non‐hexagons,
instance,
pentagon‐heptagon
pairs,
furnished
aromatic
antiaromatic
characteristics,
open‐shell
In
order
to
meet
growing
demand
versatile
in
materials
science,
research
on
novel
heteroatom
doped
non‐hexagonal
pairs
has
been
aroused
recent
years.
this
review,
we
focus
nitrogen‐doped
paris
including
synthesis,
structure
analysis,
photophysical
properties,
potential
applications
organic
devices.
Angewandte Chemie International Edition,
Год журнала:
2024,
Номер
unknown
Опубликована: Ноя. 18, 2024
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