Journal of the American Chemical Society,
Journal Year:
2024,
Volume and Issue:
146(43), P. 29664 - 29674
Published: Oct. 17, 2024
Singlet
fission
(SF)
and
triplet-triplet
annihilation
upconversion
(TTA-UC)
nominally
enable
the
interconversion
of
higher-energy
singlet
states
with
two
lower-energy
triplet
vice
versa,
both
processes
having
envisaged
application
for
enhanced
solar
power
devices.
The
mechanism
SF/TTA-UC
involves
a
complex
array
different
multiexcitonic
triplet-pair
that
are
coupled
by
exchange
interaction
to
varying
extents.
In
this
work
family
bounded
intramolecular
SF
materials,
based
upon
chromophore
1,6-diphenyl-1,3,5-hexatriene,
were
designed
synthesized.
Their
behavior
was
characterized
using
fluorescence
lifetime,
transient
absorption,
magnetic
field
dependence
studies.
capacity
formation
weakly
exchange-coupled
pairs,
subsequent
spin-evolution,
is
shown
be
strongly
dependent
combined
factors
oligomer
size
geometry.
By
contextualizing
these
results
wider
literature,
we
present
general
schematic
model
greater
completeness
than
portrayed
elsewhere.
Chemical Science,
Journal Year:
2024,
Volume and Issue:
unknown
Published: Jan. 1, 2024
An
array
of
thiophene-based
π-conjugated
linkers
in
covalently
linked
pentacene
dimers
allow
us
to
access
diverse
quantum
interference
(QI),
modulating
nonadiabatic
coupling
(NAC)
the
singlet
fission
(SF)
process.
Simulations
show
that
structural
isomerism
terms
S
atom
orientation
substantially
alters
NAC
with
relatively
marginal
impacts
on
energies.
Extended
curly
arrow
rules
(ECARs)
reveal
sensitive
dependence
QI
SF
linker
topologies
and
connectivity,
categorizing
regimes
constructive,
destructive,
previously
unrealized
research,
shifted
destructive
QI.
Drastic
changes
are
rationalized
based
nature
Our
results
from
nonequilibrium
Green's
function
calculation
using
density
functional
theory
corroborate
classification
ECARs.
Moreover,
we
found
extent
charge
resonance
contribution
electronic
states
relevant
multiexciton
formation
appearance
optically
allowed
transfer
excitation
strongly
depends
operative
regime.
Notably,
magnitude
effectively
captures
this
influence.
findings
can
rationalize
semi-quantitatively
correlate
for
step
Angewandte Chemie,
Journal Year:
2024,
Volume and Issue:
unknown
Published: Oct. 15, 2024
Abstract
Various
analogues
of
the
alkylsilylacetylene
group
are
frequently
used
as
auxiliary
groups
to
enhance
solubility
and
stability
acene
dimer
core,
widely
platforms
investigate
intramolecular
singlet
fission
(iSF)
mechanisms.
However,
while
in
2,2’‐linked
dimers
they
primarily
groups,
these
essential
fragments
bridging
units
6,6’/5,5’‐linked
dimers,
two
preferred
choices
for
dimerization.
The
starkly
different
iSF
dynamics
observed
variants
raise
question
what
role
acetylene
bridges
play.
Here,
we
systematically
designed
a
set
(oligo−)
para
‐phenylene
bridged
pentacene
with
an
additional
fragment
unit
mimic
structure
6,6’‐linked
dimers.
Contrasting
results
previously
reported
analogous
reveals
that
contribute
significant
conformational
freedom.
This
effect
provides
mechanism
promote
spin
evolution
within
triplet
pair
achieve
free
triplets
but
also
offers
new
parasitic
pathways
triplet‐pair
recombination,
revealing
this
structural
motif
can
be
both
boon
nuisance.
Additionally,
our
analysis
directly
modify
electronic
states,
highlighting
pitfalls
standard
chromophore‐bridge‐chromophore
framework
design
interpret
photophysics
materials.
Angewandte Chemie International Edition,
Journal Year:
2024,
Volume and Issue:
unknown
Published: Oct. 15, 2024
Abstract
Various
analogues
of
the
alkylsilylacetylene
group
are
frequently
used
as
auxiliary
groups
to
enhance
solubility
and
stability
acene
dimer
core,
widely
platforms
investigate
intramolecular
singlet
fission
(iSF)
mechanisms.
However,
while
in
2,2’‐linked
dimers
they
primarily
groups,
these
essential
fragments
bridging
units
6,6’/5,5’‐linked
dimers,
two
preferred
choices
for
dimerization.
The
starkly
different
iSF
dynamics
observed
variants
raise
question
what
role
acetylene
bridges
play.
Here,
we
systematically
designed
a
set
(oligo−)
para
‐phenylene
bridged
pentacene
with
an
additional
fragment
unit
mimic
structure
6,6’‐linked
dimers.
Contrasting
results
previously
reported
analogous
reveals
that
contribute
significant
conformational
freedom.
This
effect
provides
mechanism
promote
spin
evolution
within
triplet
pair
achieve
free
triplets
but
also
offers
new
parasitic
pathways
triplet‐pair
recombination,
revealing
this
structural
motif
can
be
both
boon
nuisance.
Additionally,
our
analysis
directly
modify
electronic
states,
highlighting
pitfalls
standard
chromophore‐bridge‐chromophore
framework
design
interpret
photophysics
materials.
Journal of the American Chemical Society,
Journal Year:
2024,
Volume and Issue:
146(43), P. 29664 - 29674
Published: Oct. 17, 2024
Singlet
fission
(SF)
and
triplet-triplet
annihilation
upconversion
(TTA-UC)
nominally
enable
the
interconversion
of
higher-energy
singlet
states
with
two
lower-energy
triplet
vice
versa,
both
processes
having
envisaged
application
for
enhanced
solar
power
devices.
The
mechanism
SF/TTA-UC
involves
a
complex
array
different
multiexcitonic
triplet-pair
that
are
coupled
by
exchange
interaction
to
varying
extents.
In
this
work
family
bounded
intramolecular
SF
materials,
based
upon
chromophore
1,6-diphenyl-1,3,5-hexatriene,
were
designed
synthesized.
Their
behavior
was
characterized
using
fluorescence
lifetime,
transient
absorption,
magnetic
field
dependence
studies.
capacity
formation
weakly
exchange-coupled
pairs,
subsequent
spin-evolution,
is
shown
be
strongly
dependent
combined
factors
oligomer
size
geometry.
By
contextualizing
these
results
wider
literature,
we
present
general
schematic
model
greater
completeness
than
portrayed
elsewhere.
