44 research outputs found
Preparation, Structure, and Redox Behavior of Bis(diarylmethylene)dihydrothiophene and Its π‑Extended Analogues
The
preparation, X-ray structure, and optoelectronic properties
of bisÂ(diarylmethylene)Âdihydrothiophene <b>1</b> and its Ï€-extended
analogues <b>2</b> are described. The development of a simple,
short-step synthetic route allowed us to prepare derivatives with
different aryl units. X-ray crystallographic analysis of <b>1b</b> and <b>2b</b> revealed their quinoidal structures, which exhibit
strong electronic absorption in the visible region. Cyclic voltammetry
measurements revealed their strong electron-donating properties. <b>1b</b> showed two-step electrochromic behavior between the corresponding
radical cation and dication
Preparation, Structure, and Redox Behavior of Bis(diarylmethylene)dihydrothiophene and Its π‑Extended Analogues
The
preparation, X-ray structure, and optoelectronic properties
of bisÂ(diarylmethylene)Âdihydrothiophene <b>1</b> and its Ï€-extended
analogues <b>2</b> are described. The development of a simple,
short-step synthetic route allowed us to prepare derivatives with
different aryl units. X-ray crystallographic analysis of <b>1b</b> and <b>2b</b> revealed their quinoidal structures, which exhibit
strong electronic absorption in the visible region. Cyclic voltammetry
measurements revealed their strong electron-donating properties. <b>1b</b> showed two-step electrochromic behavior between the corresponding
radical cation and dication
Thermosalient Effect of 5‑Fluorobenzoyl-4-(4-methoxyphenyl)ethynyl-1-methylimidazole without Phase Transition
5‑Fluorobenzoyl-4-(4-methoxyphenyl)ethynyl-1-methylimidazole 1 exhibited a thermosalient effect without phase transition.
The crystal of 1 was jumped by heating to about 80 °C
using a hot plate. No phase transition peak was observed at this temperature
range according to DSC measurement, unlike renowned thermosalient
crystals. Variable-temperature X-ray crystal structure analyses revealed
that anisotropical cell constant expansion resulting from the torsion
angle change between the imidazole group and carbonyl moiety induced
unit cell constant expansion and the thermosalient effect
Thermosalient Effect of 5‑Fluorobenzoyl-4-(4-methoxyphenyl)ethynyl-1-methylimidazole without Phase Transition
5‑Fluorobenzoyl-4-(4-methoxyphenyl)ethynyl-1-methylimidazole 1 exhibited a thermosalient effect without phase transition.
The crystal of 1 was jumped by heating to about 80 °C
using a hot plate. No phase transition peak was observed at this temperature
range according to DSC measurement, unlike renowned thermosalient
crystals. Variable-temperature X-ray crystal structure analyses revealed
that anisotropical cell constant expansion resulting from the torsion
angle change between the imidazole group and carbonyl moiety induced
unit cell constant expansion and the thermosalient effect
Protonic Conductivity and Hydrogen Bonds in (Haloanilinium)(H<sub>2</sub>PO<sub>4</sub>) Crystals
Brønsted acid–base reactions
between phosphoric acid
(H<sub>3</sub>PO<sub>4</sub>) and haloanilines in alcohols formed
1:1 proton-transferred ionic salts of (X-anilinium<sup>+</sup>)Â(H<sub>2</sub>PO<sub>4</sub><sup>–</sup>) and 2:1 ones of (X-anilinium<sup>+</sup>)<sub>2</sub>(HPO<sub>4</sub><sup>2–</sup>) (X = F,
Cl, Br, and I at o, m, and p positions of anilinium). Only the former
1:1 single crystals showed proton conductivity under the N<sub>2</sub> condition, and the latter 2:1 crystals became protonic insulators.
In crystals, diverse hydrogen-bonding structures from 1D to 2D networks
were achieved by modification of the molecular structure of X-anilinium
cations. The protonic conductivity was associated with the connectivity
of H<sub>2</sub>PO<sub>4</sub><sup>–</sup> anions in the hydrogen-bonding
networks. The hydrogen-bonding ladder chains in (<i>o</i>-cloroanilinim)Â(H<sub>2</sub>PO<sub>4</sub><sup>–</sup>) and
(<i>o</i>-bromoanilinim)Â(H<sub>2</sub>PO<sub>4</sub><sup>–</sup>) resulted in the highest protonic conductivity of
∼10<sup>–3</sup> S cm<sup>–1</sup>. The protonic
conductivity of the ladder-chain (H<sub>2</sub>PO<sub>4</sub><sup>–</sup>) arrangements was higher than that of 2D sheets. The
motional freedom of protons was analyzed by difference Fourier analysis
of the single-crystal X-ray structure. The 2D layer, including (H<sub>2</sub>PO<sub>4</sub><sup>–</sup>)<sub>2</sub> dimers and
(H<sub>2</sub>PO<sub>4</sub><sup>–</sup>)<sub>4</sub> tetramers,
showed relatively low protonic conductivity, and the activation energy
for proton conductivity was lowered by increasing the hydrogen-bonding
connectivity and uniformity between H<sub>2</sub>PO<sub>4</sub><sup>–</sup> anions
Collective In-Plane Molecular Rotator Based on Dibromoiodomesitylene π‑Stacks
Interest
in artificial solid-state molecular rotator systems is growing as
they enable systems to be designed for achieving specific physical
functions. The phase transition behavior of four halomesitylene crystals
indicated dynamic in-plane molecular rotator characteristics in dibromoiodomesitylene,
tribromomesitylene, and dibromomesitylene crystals. Such molecular
rotation in diiodomesitylene crystals was suppressed by effective
I···I intermolecular interactions. The in-plane molecular
rotation accompanied by a change in dipole moment resulted in dielectric
phase transitions in polar dibromoiodomesitylene and dibromomesitylene
crystals. No dielectric anomaly was observed for the in-plane molecular
rotation of tribromomesitylene in the absence of this dipole moment
change. Typical antiferroelectric–paraelectric phase transitions
were observed in the dibromomesitylene crystal, whereas the dielectric
anomaly of dibromoiodomesitylene crystals was associated with the
collective in-plane molecular rotation of polar π-molecules
in the π-stack. We found that the single-rope-like collective
in-plane molecular rotator was dominated by intermolecular I···I
interactions along the π-stacking column of polar dibromoiodomesitylene
Carrier Concentration Dependent Conduction in Insulator-Doped Donor/Acceptor Chain Compounds
On
the basis of the concept that the design of a mixed valence
system is a key route to create electronic conducting frameworks,
we propose a unique idea to rationally produce mixed valency in an
ionic donor/acceptor chain (i.e., D<sup>+</sup>A<sup>–</sup> chain). The doping of a redox-inert (insulator) dopant (P) into
a D<sup>+</sup>A<sup>–</sup> chain in place of neutral D enables
the creation of mixed valency A<sup>0</sup>/A<sup>–</sup> domains
between P units: P–(D<sup>+</sup>A<sup>–</sup>)<sub><i>n</i></sub>A<sup>0</sup>–P, where <i>n</i> is directly dependent on the dopant ratio, and charge transfer through
the P units leads to electron transport along the framework. This
hypothesis was experimentally demonstrated in an ionic DA chain synthesized
from a redox-active paddlewheel [Ru<sub>2</sub><sup>II,II</sup>] complex
and TCNQ derivative by doping with a redox-inert [Rh<sub>2</sub><sup>II,II</sup>] complex
Carrier Concentration Dependent Conduction in Insulator-Doped Donor/Acceptor Chain Compounds
On
the basis of the concept that the design of a mixed valence
system is a key route to create electronic conducting frameworks,
we propose a unique idea to rationally produce mixed valency in an
ionic donor/acceptor chain (i.e., D<sup>+</sup>A<sup>–</sup> chain). The doping of a redox-inert (insulator) dopant (P) into
a D<sup>+</sup>A<sup>–</sup> chain in place of neutral D enables
the creation of mixed valency A<sup>0</sup>/A<sup>–</sup> domains
between P units: P–(D<sup>+</sup>A<sup>–</sup>)<sub><i>n</i></sub>A<sup>0</sup>–P, where <i>n</i> is directly dependent on the dopant ratio, and charge transfer through
the P units leads to electron transport along the framework. This
hypothesis was experimentally demonstrated in an ionic DA chain synthesized
from a redox-active paddlewheel [Ru<sub>2</sub><sup>II,II</sup>] complex
and TCNQ derivative by doping with a redox-inert [Rh<sub>2</sub><sup>II,II</sup>] complex
Carrier Concentration Dependent Conduction in Insulator-Doped Donor/Acceptor Chain Compounds
On
the basis of the concept that the design of a mixed valence
system is a key route to create electronic conducting frameworks,
we propose a unique idea to rationally produce mixed valency in an
ionic donor/acceptor chain (i.e., D<sup>+</sup>A<sup>–</sup> chain). The doping of a redox-inert (insulator) dopant (P) into
a D<sup>+</sup>A<sup>–</sup> chain in place of neutral D enables
the creation of mixed valency A<sup>0</sup>/A<sup>–</sup> domains
between P units: P–(D<sup>+</sup>A<sup>–</sup>)<sub><i>n</i></sub>A<sup>0</sup>–P, where <i>n</i> is directly dependent on the dopant ratio, and charge transfer through
the P units leads to electron transport along the framework. This
hypothesis was experimentally demonstrated in an ionic DA chain synthesized
from a redox-active paddlewheel [Ru<sub>2</sub><sup>II,II</sup>] complex
and TCNQ derivative by doping with a redox-inert [Rh<sub>2</sub><sup>II,II</sup>] complex
Carrier Concentration Dependent Conduction in Insulator-Doped Donor/Acceptor Chain Compounds
On
the basis of the concept that the design of a mixed valence
system is a key route to create electronic conducting frameworks,
we propose a unique idea to rationally produce mixed valency in an
ionic donor/acceptor chain (i.e., D<sup>+</sup>A<sup>–</sup> chain). The doping of a redox-inert (insulator) dopant (P) into
a D<sup>+</sup>A<sup>–</sup> chain in place of neutral D enables
the creation of mixed valency A<sup>0</sup>/A<sup>–</sup> domains
between P units: P–(D<sup>+</sup>A<sup>–</sup>)<sub><i>n</i></sub>A<sup>0</sup>–P, where <i>n</i> is directly dependent on the dopant ratio, and charge transfer through
the P units leads to electron transport along the framework. This
hypothesis was experimentally demonstrated in an ionic DA chain synthesized
from a redox-active paddlewheel [Ru<sub>2</sub><sup>II,II</sup>] complex
and TCNQ derivative by doping with a redox-inert [Rh<sub>2</sub><sup>II,II</sup>] complex