Journal of the American Chemical Society,
Journal Year:
2024,
Volume and Issue:
146(23), P. 15659 - 15665
Published: May 31, 2024
Molecular
aggregation
is
a
powerful
tool
for
tuning
advanced
materials'
photophysical
and
electronic
properties.
Here
we
present
novel
potential
the
aqueous-solvated
aggregated
state
of
boron
dipyrromethene
(BODIPY)
to
facilitate
phototransformations
otherwise
achievable
only
under
harsh
chemical
conditions.
We
show
that
photoinduced
symmetry-breaking
charge
separation
can
itself
initiate
catalyst-free
redox
chemistry,
leading
selective
α-C(sp
Chemical Science,
Journal Year:
2022,
Volume and Issue:
13(36), P. 10824 - 10835
Published: Jan. 1, 2022
Achieving
long-lived
symmetry-broken
charge-separated
states
in
chromophoric
assemblies
is
quintessential
for
enhanced
performance
of
artificial
photosynthetic
mimics.
However,
the
occurrence
energy
trap
hinders
exciton
and
charge
transport
across
photovoltaic
devices,
diminishing
power
conversion
efficiency.
Herein,
we
demonstrate
unprecedented
excimer
formation
relaxed
excited-state
geometry
bichromophoric
systems
impeding
lifetime
states.
Core-annulated
perylenediimide
dimers
(SC-SPDI2
SC-NPDI2)
prefer
a
near-orthogonal
arrangement
ground
state
π-stacked
foldamer
structure
excited
state.
The
prospect
an
excimer-like
foldameric
SC-SPDI2
SC-NPDI2
has
been
rationalized
by
fragment-based
analysis
temperature-dependent
photoluminescence
measurements.
Effective
electronic
coupling
matrix
elements
Franck-Condon
facilitate
solvation-assisted
ultrafast
symmetry-breaking
charge-separation
(SB-CS)
high
dielectric
environment,
contrast
to
unrelaxed
(Ex*)
low
environment.
Subsequently,
SB-CS
dissociates
into
undesired
(Ex)
due
configuration
mixing
Frenkel
(FE)
structure,
downgrading
efficacy
decay
rate
constant
FE
(kFE→SB-CS)
polar
solvents
8-17
fold
faster
than
that
direct
Ex*
(kFE→Ex*)
non-polar
solvent
(kFE→SB-CS≫kFE→Ex*),
characterized
femtosecond
transient
absorption
(fsTA)
spectroscopy.
present
investigation
establishes
impact
detrimental
on
persistence
offers
requisite
conformational
rigidity
as
one
potential
design
principles
developing
advanced
molecular
photovoltaics.
Journal of the American Chemical Society,
Journal Year:
2024,
Volume and Issue:
146(8), P. 5543 - 5549
Published: Feb. 14, 2024
High
quantum-yield
charge
carrier
generation
from
the
initially
prepared
excitons
defines
a
key
step
in
light-harvesting
and
conversion
scheme.
Photoinduced
transfer
molecular
electron
donor–acceptor
assemblies
is
driven
by
sizable
ΔG0,
which
compromises
potential
of
generated
carriers.
Reminiscent
special
pair
at
reaction
center
natural
complex,
symmetry-breaking
(SBCT)
within
identical
struts
metal−organic
framework
(MOF)
will
facilitate
efficient
long-lived
carriers
with
maximized
potentials
without
incorporating
any
foreign
redox
species.
We
report
SBCT
pyrene-based
zirconium
metal–organic
NU-1000
that
leads
to
radical
ions
polar
solvent
bound
CT
states
low-polar
solvent.
The
probe
unveils
role
low-lying
non-Franck–Condon
excitonic
as
intermediates
formation
state
Franck–Condon
S1
states.
Ultrafast
transient
spectroscopy─probed
over
200
fs-30
μs
time
scale─evinces
kSBCT
=
(110
ps)−1
media
(εs
37.5)
forming
solvated
recombination
rate
kCR
(∼45
ns)−1.
A
slower
(203
was
recorded
7.0)
manifesting
[TBAPy•+
TBAPy•–]
≈
(17
μs)−1.
This
discovery,
along
other
unique
photophysical
features
relevant
light
harvesting,
should
define
MOF-based
platform
for
developing
heterogeneous
artificial
photon
energy
systems.
Angewandte Chemie International Edition,
Journal Year:
2024,
Volume and Issue:
63(29)
Published: May 3, 2024
Abstract
Integrating
aggregation‐induced
emission
(AIE)
into
thermally
activated
delayed
fluorescence
(TADF)
emitters
holds
great
promise
for
the
advancement
of
highly
efficient
organic
light
emitting
diodes
(OLEDs).
Despite
recent
advancements,
a
thorough
comprehension
underlying
mechanisms
remains
imperative
practical
application
such
materials.
In
this
work,
we
introduce
novel
approach
aimed
at
modulating
TADF
process
by
manipulating
dynamic
processes
in
excited
states
through
aggregation
effect.
Our
findings
reveal
that
not
only
enhances
both
prompt
and
simultaneously
but
also
imposes
constraints
on
molecular
reorientation.
This
constraint
reinforces
spin‐orbit
coupling
reduces
energy
gap
between
singlets
triplets.
These
insights
deepen
our
understanding
fundamental
governing
effect
materials
provide
valuable
guidance
design
high‐efficiency
photoluminescent
The Journal of Physical Chemistry Letters,
Journal Year:
2024,
Volume and Issue:
15(10), P. 2834 - 2840
Published: March 5, 2024
So
far,
symmetry-breaking
charge
separation
(SB-CS)
has
been
observed
with
a
limited
number
of
chromophores
and
is
usually
inhibited
by
the
formation
an
excimer.
We
show
here
that
thanks
to
fine-tuning
interchromophore
coupling
via
structural
control,
SB-CS
can
be
operative
pyrene,
despite
its
high
propensity
form
This
realized
bichromophoric
system
consisting
two
pyrenes
attached
crown
ether
macrocycle,
which
bind
cations
different
sizes.
By
combining
stationary
time-resolved
spectroscopy
together
molecular
dynamics
simulations,
we
demonstrate
excited-state
totally
changed
depending
on
binding
cation.
Whereas
strong
leads
rapid
excimer
formation,
too
weak
results
in
noninteracting
chromophores.
However,
intermediate
coupling,
achieved
upon
Mg2+,
allows
for
operative.
The Journal of Physical Chemistry Letters,
Journal Year:
2023,
Volume and Issue:
14(3), P. 702 - 708
Published: Jan. 16, 2023
In
this
work,
the
photoinduced
charge
separation
(CS)
via
symmetry
breaking
in
an
orthogonal
meso-β-linked
boron
dipyrromethene
(BODIPY)
dimer
was
investigated
by
polarized
transient
absorption
spectroscopy.
The
time
constant
about
0.76
ps
of
CS
reaction
determined
dimethyl
sulfoxide
is
much
faster
than
solvation
dynamics.
observed
anisotropy
BODIPY
anion
band
implies
that
both
hole
and
electron
transfers
occur
with
similar
probabilities.
bidirectional
transfer
processes
suggest
locally
excited
state
weakly
coupled
to
polar
solvent,
excited-state
structural
relaxation
within
monomeric
unit
rather
limited.
combination
electronic
excitation
analysis
based
on
time-dependent
density-functional
theory
calculations,
we
deduced
enabled
torsional
motion
associated
covalently
connected
units,
promoting
coupling,
irrelevant
dynamic
solvent
relaxation.
Chemical Science,
Journal Year:
2023,
Volume and Issue:
15(3), P. 906 - 913
Published: Dec. 15, 2023
Symmetry
breaking
charge
transfer
followed
by
separation
with
appreciable
lifetimes
has
been
demonstrated
in
a
newly
synthesized
bisstyrylBODIPY
dimer
polar
solvents
using
pump-probe
and
other
techniques.
Journal of the American Chemical Society,
Journal Year:
2024,
Volume and Issue:
146(15), P. 10875 - 10888
Published: April 5, 2024
Two
isomeric
pentacene
dimers,
each
linked
by
a
diamantane
spacer,
have
been
synthesized.
These
dimers
are
designed
to
provide
experimental
evidence
support
quantum
mechanical
calculations,
which
predict
the
substitution
pattern
on
carbon-rich
diethynyldiamantane
spacer
be
decisive
in
controlling
interpentacene
coupling.
Intramolecular
singlet
fission
(i-SF)
serves
as
probe
for
existence
and
strength
of
electronic
coupling
between
two
pentacenes,
with
transient
absorption
spectroscopy
method
choice
characterize
i-SF.
4,9-Substitution
provides
dimer
(4,9-dimer)
chromophores
completely
decoupled
that,
following
photoexcitation,
deactivates
ground
state
analogous
monomeric
chromophore.
Conversely,
1,6-substitution
(1,6-dimer)
that
exhibits
sufficiently
strong
drive
i-SF,
resulting
correlated
triplet
M(T1T1)
yields
close
unity
free
(T1
+
T1)
ca.
50%.
Thus,
effectively
switches
"on"
or
"off"
chromophores,
based
pattern.
The
binary
control
contrasts
other
known
molecular
spacers
only
modulate
pentacenes.
The Journal of Physical Chemistry Letters,
Journal Year:
2023,
Volume and Issue:
14(1), P. 253 - 259
Published: Jan. 3, 2023
Symmetry
breaking
charge
separation
(SBCS)
is
central
to
photochemical
energy
conversion.
The
widely
studied
9,9-bianthryl
(9,9'BA)
the
prototype,
but
role
of
bianthryl
structure
hardly
investigated.
Here
we
investigate
excited
state
structural
dynamics
in
a
reduced
symmetry,
1,9-bianthryl
(1,9'BA),
through
ultrafast
electronic
and
vibrational
spectroscopy.
Resonance
selective
Raman
polar
solvents
reveals
Franck-Condon
mode
that
disappears
concomitant
with
rise
ring
breathing
modes
radical
species.
Solvent-dependent
show
CS
driven
by
solvent
orientational
motion,
as
9,9'BA.
In
nonpolar
undergoes
multistep
relaxation,
including
subpicosecond
decay
biexponential
diffusion-controlled
evolution
distorted
slightly
state.
These
data
suggest
two
possible
routes
SBCS;
established
pathway
rapidly
relaxing
and,
slowly
media,
initial
intramolecular
reorganization
which
drives
relaxation.
Chemical Science,
Journal Year:
2024,
Volume and Issue:
15(17), P. 6363 - 6377
Published: Jan. 1, 2024
Symmetry-breaking
charge
separation
(SB-CS)
has
recently
evolved
as
an
emerging
concept
offering
its
potential
to
the
latest
generation
of
organic
photovoltaics.
