Journal of the American Chemical Society,
Год журнала:
2025,
Номер
unknown
Опубликована: Апрель 22, 2025
We
report
a
photoredox-enabled
deracemization
of
cyclic
α-aryl
ketones
that
occurs
with
high
stereoselectivity
and
yield
proceeds
by
mechanistically
distinct
proton
transfer
reactions.
This
reaction
is
jointly
mediated
visible-light
photocatalyst
chiral
phosphate
base
cocatalyst
under
blue
light
irradiation.
Notably,
the
extent
for
this
exhibits
an
unexpected
dependence
on
identity
concentration
cocatalyst,
wherein
can
be
increased
employing
photocatalysts
more
positive
ground-state
reduction
potentials,
raising
or
combination
these
factors.
effect
attributed
to
two
competing
processes,
back-electron
deprotonation,
which
consume
same
intermediate,
we
propose
kinetic
model
rationalizes
behavior.
also
demonstrate
redox
properties
impact
product-forming
step,
dominant
stereoselective
step
in
transformation.
Together,
mechanistic
insights
facilitate
deeper
understanding
complexity
light-driven
reactions
involving
reversible
electron
suggest
approaches
processes
may
increased.
Inorganic Chemistry,
Год журнала:
2024,
Номер
63(31), С. 14267 - 14277
Опубликована: Июль 20, 2024
High-throughput
synthesis
and
screening
(HTSS)
methods
were
used
to
investigate
the
photophysical
properties
of
576
heteroleptic
Rh(III)
transition-metal
complexes
through
measurement
UV–visible
absorption
spectra,
deaerated
excited-state
lifetime,
phosphorescent
emission
spectra.
While
4d
photophysics
are
often
highly
influenced
by
deleterious
metal-centered
deactivation
channels,
HTSS
structurally
diverse
cyclometalating
ancillary
ligands
attached
metal
center
facilitated
discovery
photoactive
exhibiting
long-lived
charge-transfer
phosphorescence
(0.15–0.95
μs)
spanning
a
substantial
portion
visible
region
(546–620
nm)
at
room
temperature.
Further
electrochemical
investigations
then
carried
out
on
select
with
favorable
understand
underlying
features
controlling
these
superior
properties.
Heteroleptic
Ir(III)
identical
ligand
morphology
also
synthesized
compare
this
family
well
understood
chromophores.
A
number
contained
requisite
for
photocatalytic
activity
consequently
tested
as
photocatalysts
(PCs)
in
water
reduction
system
using
Pd
cocatalyst.
Under
certain
conditions,
PC
actually
surpassed
that
PC,
uncovering
potential
often-overlooked
class
transition
metals
both
efficient
chromophores
PCs.
Journal of the American Chemical Society,
Год журнала:
2024,
Номер
146(32), С. 22818 - 22828
Опубликована: Июль 30, 2024
The
cage
escape
yield,
i.e.,
the
separation
of
geminate
radical
pair
formed
immediately
after
bimolecular
excited-state
electron
transfer,
was
studied
in
11
solvents
using
six
Fe(III),
Ru(II),
and
Ir(III)
photosensitizers
tri-p-tolylamine
as
donor.
Among
all
complexes,
largest
yields
(0.67–1)
were
recorded
for
photosensitizer,
showing
highest
potential
a
photocatalyst
photoredox
catalysis.
These
dropped
to
values
around
0.65
both
Ru(II)
0.38
Os(II)
photosensitizer.
Interestingly,
open-shell
Fe(III)
small
(<0.1)
with
dielectric
constant
greater
than
20
but
shown
reach
up
0.58
low
constants.
results
presented
herein
on
closed-shell
suggest
that
rate
triplet–singlet
intersystem
crossing
within
manifold
states
implies
charge
recombination
toward
ground
state
is
spin-forbidden
process,
favoring
large
are
not
influenced
by
effects.
Geminate
metal
such
two
herein,
no
longer
process
becomes
highly
sensitive
solvent
Altogether,
this
study
provides
general
guidelines
factors
influencing
reactivity
prototypical
also
allows
one
foresee
great
development
2LMCT
excited
catalysis,
providing
constants
used.
Journal of the American Chemical Society,
Год журнала:
2025,
Номер
unknown
Опубликована: Апрель 22, 2025
We
report
a
photoredox-enabled
deracemization
of
cyclic
α-aryl
ketones
that
occurs
with
high
stereoselectivity
and
yield
proceeds
by
mechanistically
distinct
proton
transfer
reactions.
This
reaction
is
jointly
mediated
visible-light
photocatalyst
chiral
phosphate
base
cocatalyst
under
blue
light
irradiation.
Notably,
the
extent
for
this
exhibits
an
unexpected
dependence
on
identity
concentration
cocatalyst,
wherein
can
be
increased
employing
photocatalysts
more
positive
ground-state
reduction
potentials,
raising
or
combination
these
factors.
effect
attributed
to
two
competing
processes,
back-electron
deprotonation,
which
consume
same
intermediate,
we
propose
kinetic
model
rationalizes
behavior.
also
demonstrate
redox
properties
impact
product-forming
step,
dominant
stereoselective
step
in
transformation.
Together,
mechanistic
insights
facilitate
deeper
understanding
complexity
light-driven
reactions
involving
reversible
electron
suggest
approaches
processes
may
increased.
