Angewandte Chemie,
Год журнала:
2023,
Номер
136(16)
Опубликована: Дек. 13, 2023
Abstract
Wir
berichten
über
die
Darstellung
eines
neuen
organischen
σ‐Donors
mit
einem
C
6
H
4
‐Linker
zwischen
N
‐heterozyklischen
Carben
(NHC)
und
einer
exozyklischen
Methylidengruppe,
den
wir
als
‐heterozyklisches
Chinodimethan
(NHQ)
bezeichnen.
Die
Aromatisierung
des
‐Linkers
liefert
eine
entscheidende
Triebkraft
für
Reaktion
NHQs
Elektrophil
macht
das
NHQ
deutlich
basischer
analoge
NHCs
oder
‐heterozyklische
Olefine
(NHOs),
wie
DFT‐Berechnungen
Konkurrenzexperimente
zeigen.
In
Lösung
findet
beim
unerwartete
Kopf‐Kopf‐Dimerisierung
unter
formaler
Wasserstofffreisetzung
durch
C−C‐Kopplung
der
Methylidengruppen
statt.
zeigen,
dass
diese
einen
offenschaligen
Singulettpfad
verläuft,
was
auf
diradikalischen
Charakter
hinweist.
Das
Produkt
dieser
Dimerisierung
kann
konjugiertes
Bis‐Chinodimethan
beschrieben
werden,
laut
zyklischer
Voltammetrie
ein
starkes
organisches
Reduktionsmittel
ist
(
E
1/2
=−1.71
V
vs.
Fc/Fc
+
)
bemerkenswert
kleine
Singulett–Triplett‐Lücke
von
Δ
S→T
=4.4
kcal
mol
−1
aufweist.
Journal of the American Chemical Society,
Год журнала:
2024,
Номер
146(13), С. 9004 - 9011
Опубликована: Март 19, 2024
Herein,
we
report
the
syntheses
and
electronic
structures
of
crystalline
dianionic
as
well
neutral
diboron-centered
classical
diradicaloids
boron
analogues
Thiele,
Chichibabin,
Müller
(this
only
for
diradicaloids!)
hydrocarbons.
These
are
based
on
borane
radical
anion
NHC-stabilized
boryl
spin
carriers,
respectively.
All
these
exhibit
triplet
population
at
room
temperature
regardless
π-conjugated
spacer:
p-phenylene,
p,p′-biphenylene,
or
p,p″-terphenylene.
In
case
diradicaloids,
employed
spacer
plays
a
crucial
role
temperature:
EPR
inactive
p-phenylene
vs
active
p,p′-biphenylene.
The
findings
emphasize
importance
carriers
resulting
ground-state:
along
with
pivotal
spin-coupler
between
two
spins.
Notably,
100
years
(a
century)
after
first
by
Krause
triphenyl
radical-anion,
being
isoelectronic
to
triphenylmethyl
radical,
convey
anion-based
diradicaloids.
Furthermore,
while
donor-stabilized
radicals
were
introduced
in
1980s
Giles
Roberts,
said
concept
is
herewith
extended
radical-based
Chemistry - A European Journal,
Год журнала:
2024,
Номер
30(35)
Опубликована: Апрель 22, 2024
Upon
dibenzo
annulation
on
Thiele's
hydrocarbon
(tetraphenyl-p-quinodimethane),
the
quinoid
form
and
biradical
adopt
quite
different
geometries,
thus
are
no
longer
resonance
structures.
When
these
two
forms
can
interconvert
rapidly
due
to
small
energy
barrier
(ΔG
Journal of the American Chemical Society,
Год журнала:
2025,
Номер
unknown
Опубликована: Апрель 15, 2025
Topochemical
polymerization
(TCP)
represents
an
essential
route
to
create
regio-
and
stereoregular
polymers
through
solid-state
transformations.
Herein,
we
present
innovative
strategy
for
controlling
topochemical
pathways
by
tailoring
the
terminal
group
aromaticity
in
para-azaquinodimethane
(AQM)
ring
system.
Substituting
phenyl
groups
with
less
aromatic
furyl
units
extends
significant
spin
density
delocalization
across
conjugated
core
upon
thermal
activation,
inducing
diradicaloid
characters
at
positions
enabling
unconventional
reactivities
both
solution
solid
states.
Thermal
treatment
toluene
yields
a
unique
cyclophane
dimer
formed
via
furyl-methine
C-C
coupling,
confirmed
X-ray
crystallography,
while
reactions
produce
intercolumnar
coupling
intracolumnar
methine-methine
coupling.
The
spin-center-directed
mechanism
underlying
these
transformations
is
validated
theoretical
modeling
isotopic
labeling
experiments.
This
study
highlights
prowess
of
modulation
functional
pro-aromatic
systems,
which
enables
synthesis
main
chain
structures
that
are
otherwise
difficult
access.
Chemistry - An Asian Journal,
Год журнала:
2024,
Номер
19(17)
Опубликована: Май 31, 2024
Tricolor
electrochromism
was
realized
through
the
interconversion
among
neutral
(yellow),
dicationic
(green),
and
tetracationic
(blue)
states,
even
though
only
one
kind
of
chromophore
is
generated
upon
oxidation.
Both
states
were
isolated
as
stable
salts,
their
different
colors
come
from
effective
inter-chromophore
interaction
in
state
but
not
state.
Despite
negligible
Coulombic
repulsion
with
four
cyanine-type
chromophores,
pentacenebisquinodimethane
undergoes
stepwise
two-stage
two-electron
oxidation
when
radical-stabilizing
5-(4-octyloxyphenyl)-2-thienyl
groups
are
attached
on
exomethylene
bonds.
A
contribution
biradical
form
reason
for
observed
negative
cooperativity
during
electrochemical
Advanced Functional Materials,
Год журнала:
2024,
Номер
34(47)
Опубликована: Апрель 15, 2024
Abstract
Many
of
the
functions
and
features
practically
useful
materials
are
province
molecular‐level
chemistry
their
modulation
at
different
length‐scale.
This
report
illustrates
behind
[2.2]paracyclophane‐based
with
a
particular
focus
on
most
recent
explorations
through‐space
conjugated
small‐molecule
organic
emitters,
π‐stacked
macrocyclic
molecules
polymers,
poly(p‐phenylenevinylene)s
featuring
well‐defined
donor‐acceptors
sequence
control,
surface
engineering
technologically‐relevant
parylenes
that
finds
broad
applications
across
field
chemical
science
technology.
largely
deals
potential
opportunities
associated
molecular
planar
chirality,
conformational
behaviors,
strain‐induced
non‐planarity
aromatics,
profound
impacts
conjugation
π‐electron
interactions/delocalization
optoelectronic
properties
π‐conjugated
polymers
extended
structures
consisting
cyclophanes.
A
special
is
put
concept
supramolecular
using
chemically‐programmed
chiral
cyclophanes
via
non‐covalent
stacking
controlled
arrangements.
Illustrating
cyclophane
as
precursors/monomers
fabrication
strategies
for
incorporation
in
structurally‐controlled
(poly(
p
‐xylylene)s
formed
vapor
deposition
polymerization
post‐deposition
interface
described.
Demonstrating
rather
approach
electronically‐dictated
ring‐opening
metathesis
employing
strained
cyclophane‐diene
precursors
generate
poly(
‐phenylenevinylene)s
(i.e.,
low
dispersity)
donor‐acceptor
control
also
discussed.
will
serve
an
indispensable
one‐stop
reference
organic,
polymer
chemists,
well
material
scientists
working
research
innovations.
Faraday Discussions,
Год журнала:
2024,
Номер
254, С. 107 - 129
Опубликована: Янв. 1, 2024
Diradicals
are
of
high
current
interest
as
emerging
materials
for
next
generation
optoelectronic
applications.
To
tune
their
excited-state
properties
it
would
be
greatly
beneficial
to
have
a
detailed
understanding
the
wave
functions
different
states
involved
but
this
endeavour
is
hampered
by
formal
and
practical
barriers.
tackle
these
challenges,
we
present
analysis
well
concrete
results
on
diradical
excited
states.
We
start
with
investigation
available
two-orbital
two-electron
model
viewed
from
both
valence-bond
molecular
orbital
perspectives.
highlight
presence
zwitterionic
illustrate
connections
found
in
closed-shell
molecules.
Subsequently,
introduce
protocols
analysing
realistic
multireference
computations
applying
Angewandte Chemie International Edition,
Год журнала:
2024,
Номер
63(41)
Опубликована: Июль 18, 2024
We
demonstrate
that
2-alkenylarylaldimines
and
ketimines
undergo
thermal
6π-azaelectrocyclization
to
generate
a
wide
range
of
azabicyclic
o-quinodimethanes
(o-QDMs).
These
o-QDMs
exist
as
hybrid
diene
benzylic
diradical.
The
diradical
nature
was
confirmed
by
their
ability
dimerization
react
with
H-atom
donor,
2,2,6,6-tetramethylpiperidin-1-yl)oxyl
(TEMPO)
O
