Angewandte Chemie,
Journal Year:
2024,
Volume and Issue:
unknown
Published: Oct. 31, 2024
Abstract
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,
represents
the
highest
reported
helicene
based
on
corannulene.
X‐ray
crystallography
reveals
that
adopts
a
propeller‐shaped
conformation
with
well‐preserved
corannulene
core,
while
exhibit
quasi‐propeller‐shaped
conformations.
Upon
heating,
conformer
undergoes
conversion
to
thermodynamically
more
stable
,
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
−1
.
In
contrast,
for
was
calculated
be
45.46
exceptional
chiral
stability.
Surprisingly,
bowl
inversions
conformers
are
somewhat
inhibited
by
helical
blades,
this
not
other
possible
Q[6]H
These
results
first
demonstrated
subtle
variations
can
lead
significant
changes
in
stability
multiple
helicenes.
Due
electron
complementarity,
recognize
fullerenes
both
solution
solid
state,
which
is
rare
instance
co‐crystallization
assembly
between
helicenes
fullerenes.
Organic Letters,
Journal Year:
2025,
Volume and Issue:
unknown
Published: March 28, 2025
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.
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.
Angewandte Chemie International Edition,
Journal Year:
2024,
Volume and Issue:
unknown
Published: Oct. 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
Angewandte Chemie International Edition,
Journal Year:
2025,
Volume and Issue:
unknown
Published: May 27, 2025
Abstract
The
promise
of
enhanced
circularly
polarized
luminescence
(CPL)
from
organic
molecules
has
inspired
synthetic
efforts
to
prepare
elongated
multi‐layer
helicenes.
It
proven
particularly
challenging
synthesize
and
isolate
enantiomerically
pure
multi‐turn
helicenes,
consequently,
clear
guidelines
for
the
molecular
design
helicenes
achieve
large
CPL
output
remain
elusive.
We
explore
oxidative
dimerization
a
2‐naphthol‐annulated
hetero[13]helicene,
observe
formation
two
types
structurally
distinct
hetero[27]helicenes,
both
with
four
helical
turns,
form.
With
Cu
II
Cl(OH)‐TMEDA
as
oxidant,
symmetric
dimer
(
bi[13]
)
formed,
joining
same
helicity
in
their
keto
tautomeric
forms.
Using
(OTf)₂
oxidant
led
an
unsymmetrical
[27]helicenoid
composed
by
M
)‐
P
)‐enantiomer
[13]helicene
through
unusual
coupling
between
1‐
3‐positions
2‐naphthol
units.
Structural
characterization
was
achieved
NMR
spectroscopy
single‐crystal
(X‐ray
or
electron)
diffraction
analysis.
enantiomers
this
were
analyzed
electronic
circular
dichroism
(ECD)
measurements.
spectroscopic
data
corroborated
DFT
calculations,
intense
is
preserved
despite
presence
‐helicene
molecule.
These
[27]helicenoids
are
first
isolated
structures
that
feature
π‐systems
turns.
Angewandte Chemie,
Journal Year:
2025,
Volume and Issue:
unknown
Published: May 27, 2025
Abstract
The
promise
of
enhanced
circularly
polarized
luminescence
(CPL)
from
organic
molecules
has
inspired
synthetic
efforts
to
prepare
elongated
multi‐layer
helicenes.
It
proven
particularly
challenging
synthesize
and
isolate
enantiomerically
pure
multi‐turn
helicenes,
consequently,
clear
guidelines
for
the
molecular
design
helicenes
achieve
large
CPL
output
remain
elusive.
We
explore
oxidative
dimerization
a
2‐naphthol‐annulated
hetero[13]helicene,
observe
formation
two
types
structurally
distinct
hetero[27]helicenes,
both
with
four
helical
turns,
form.
With
Cu
II
Cl(OH)‐TMEDA
as
oxidant,
symmetric
dimer
(
bi[13]
)
formed,
joining
same
helicity
in
their
keto
tautomeric
forms.
Using
(OTf)₂
oxidant
led
an
unsymmetrical
[27]helicenoid
composed
by
M
)‐
P
)‐enantiomer
[13]helicene
through
unusual
coupling
between
1‐
3‐positions
2‐naphthol
units.
Structural
characterization
was
achieved
NMR
spectroscopy
single‐crystal
(X‐ray
or
electron)
diffraction
analysis.
enantiomers
this
were
analyzed
electronic
circular
dichroism
(ECD)
measurements.
spectroscopic
data
corroborated
DFT
calculations,
intense
is
preserved
despite
presence
‐helicene
molecule.
These
[27]helicenoids
are
first
isolated
structures
that
feature
π‐systems
turns.
Angewandte Chemie International Edition,
Journal Year:
2024,
Volume and Issue:
unknown
Published: Nov. 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
Advanced Optical Materials,
Journal Year:
2024,
Volume and Issue:
unknown
Published: Dec. 16, 2024
Abstract
Thiahelicenes,
an
important
subclass
of
helicenes,
are
renowned
for
their
pronounced
chiroptical
properties,
particularly
circular
dichroism.
However,
the
exploration
circularly
polarized
luminescence
(CPL)
has
been
hindered
due
to
inherently
weak
fluorescence,
leaving
a
critical
gap
in
development
thiahelicenes
as
efficient
CPL
emitters.
To
address
this
limitation,
novel
strategy
enhancing
by
integrating
thiophene‐containing
units
with
highly
emissive
hexabenzoperylene
(HBP)
core
is
presented.
Two
isomeric
HBP‐cored
double
synthesized,
which
serve
proof
concept.
These
molecules
exhibit
exceptionally
high
fluorescence
quantum
yields
(
Φ
F
=
83%
and
91%),
surpassing
all
previously
reported
thiahelicenes.
Furthermore,
dissymmetry
factors
show
four‐fold
enhancement
compared
parent
HBP,
resulting
remarkable
brightness
up
84.9
M
−1
cm
.
findings
not
only
limitation
but
also
establish
new
pathway
developing
high‐performance
materials.
Nanoscale Advances,
Journal Year:
2024,
Volume and Issue:
6(18), P. 4567 - 4571
Published: Jan. 1, 2024
The
excited
state
dynamics
of
heterohelicenes
[9]TH
and
[9]AH
were
spectroscopically
studied.
showed
enhanced
fluorescence,
while
phosphorescence
occurred
in
due
to
its
spin–orbit
coupling
swift
intersystem
crossing.
Chemistry Letters,
Journal Year:
2024,
Volume and Issue:
53(8)
Published: July 31, 2024
Abstract
Azahelicenes
are
intriguing
luminescent
materials
with
a
planar
chirality.
The
properties
of
aza[9]helicene
can
be
perturbed
by
attaching
substituent
at
the
termini.
impact
terminal
decoration
has
been
investigated
in
view
structural
and
electronic
aspects,
leading
to
control
interlayer
interaction.