scholarly journals Thermotropic Liquid-Crystalline and Light-Emitting Properties of Poly(pyridinium) Salts Containing Various Diamine Connectors and Hydrophilic Macrocounterions

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 851 ◽  
Author(s):  
Tae Soo Jo ◽  
Haesook Han ◽  
Pradip K. Bhowmik ◽  
Benoît Heinrich ◽  
Bertrand Donnio
Keyword(s):  
Liquid Crystalline ◽  
Room Temperature ◽  
Variable Temperature ◽  
Green Light ◽  
Pyridinium Salts ◽  
Ionic Polymers ◽  
Excellent Thermal Stability ◽  
Viscous Liquids ◽  
Temperature Range ◽  
Macromolecular Systems

A set of poly(pyridinium) salts containing various diamine moieties, as molecular connectors, and poly(ethyleneglycol)-4-nonylphenyl-3-sulfopropyl ether, thereafter referred to as “Macroion”, as the hydrophilic counterion, were prepared by metathesis reaction from the respective precursory tosylated poly(pyridinium)s in methanol. The structure of these ionic polymers was established by spectroscopy and chromatography techniques. The shape-persistent ionic poly(pyridinium) materials, inserting rigid or semi-rigid diamine spacers, display thermotropic liquid-crystalline properties from room-temperature up to their isotropization (in the temperature range around 160–200 °C). The nature of the LC phases is lamellar in both cases as identified by the combination of various complementary experimental techniques including DSC, POM and variable-temperature SAXS. The other polymers, inserting bulky or flexible spacers, only form room temperature viscous liquids. These new macromolecular systems can then be referred to as polymeric ionic liquid crystals (PILCs) and or polymeric ionic liquids (PILs). All the ionic polymers show excellent thermal stability, in the 260–330 °C temperature range as determined by TGA measurements, and a good solubility in common organic solvents as well as in water. Their optical properties were characterized in both solution and solid states by UV−Vis and photoluminescent spectroscopies. They emit blue or green light in both the states and exhibit a positive solvatochromic effect.

Synthesis and thermotropic properties of hydroxy and silyloxy axially substituted phthalocyanines

2000 ◽  
Vol 04 (05) ◽  
pp. 569-573 ◽  
Author(s):  
BELÉN DEL REY ◽  
M. VICTORIA MARTÍNEZ-DÍAZ ◽  
JOAQUÍN BARBERÁ ◽  
TOMÁS TORRES
Keyword(s):  
Liquid Crystalline ◽  
Room Temperature ◽  
Amorphous Structure ◽  
Axial Position ◽  
X Ray Diffraction ◽  
Polarizing Microscopy ◽  
X Ray ◽  
Temperature Range ◽  
Isotropic Materials ◽  
Thermotropic Properties

Novel boron(III) subphthalocyanines 5-8 with six lipophilic alkylthio chains at the peripheral sites, bearing hydroxy or triethylsilyloxy groups in the axial position, have been synthesized and their thermotropic properties have been studied. These compounds are gelatinous materials at room temperature and gradually soften as the temperature is raised up to a point at which high fluidity typical of classical liquids is observed. By the usual techniques employed for the study of thermotropic behaviour (polarizing microscopy, DSC and X-ray diffraction), no liquid crystalline properties have been found. Instead, the compounds have an amorphous structure (i.e. behave as isotropic materials) throughout the temperature range studied. They could be designated as liquid subphthalocyanines.

scholarly journals Design of polar self-assembling lactic acid derivatives possessing submicrometre helical pitch

2018 ◽  
Vol 9 ◽  
pp. 333-341 ◽  
Author(s):  
Alexej Bubnov ◽  
Cyril Vacek ◽  
Michał Czerwiński ◽  
Terezia Vojtylová ◽  
Wiktor Piecek ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Liquid Crystalline ◽  
Room Temperature ◽  
Scanning Calorimetry ◽  
Alkyl Chains ◽  
Temperature Range ◽  
Helical Pitch ◽  
Self Assembling ◽  
Electro Optic ◽  
Nanoscale Level

Several new lactic acid derivatives containing the keto linkage group far from the chiral part and short alkyl chains have been synthesized and characterised by polarising optical microscopy, differential scanning calorimetry, as well as electro-optic and dielectric spectroscopy. The materials possess a self-assembling behaviour on the nanoscale level as they form polar smectic liquid crystalline mesophases, namely the orthogonal paraelectric SmA* and the tilted ferroelectric SmC* phases, in a broad temperature range down to room temperature. A short helical pitch (≈120–320 nm), relatively high spontaneous polarisation (≈150 nC/cm2) and reasonable tilt angle values have been determined within the temperature range of the tilted ferroelectric SmC* phase. The obtained results make the new materials useful for the advanced mixture design and for further utilisation in electro-optic devices based on the deformed helix ferroelectric effect.

Temperature dependence of chlorine-35 N.Q.R. in 2,6-Dichlorophenol

1978 ◽  
Vol 31 (4) ◽  
pp. 791 ◽  
Author(s):  
R Chandramani ◽  
SP Basavaraju ◽  
N Devaraj
Keyword(s):  
Temperature Dependence ◽  
Room Temperature ◽  
Temperature Range ◽  
Temperature Coefficients ◽  
Brown's Method

Chlorine n.q.r, in 2,6-dichlorophenol has been investigated at temperatures from 77 K to room temperature. Two resonance lines due to chemically inequivalent sites have been observed throughout this temperature range. Torsional frequencies of the molecule have been calculated at temperatures from 77 to 300 K according to Bayer's theory and Brown's method. Also the temperature coefficients of the torsional frequencies have been calculated.

Room-temperature discotic liquid-crystalline coronene diimides exhibiting high charge-carrier mobility in air

2009 ◽  
Vol 19 (37) ◽  
pp. 6688 ◽  
Author(s):  
Zesheng An ◽  
Junsheng Yu ◽  
Benoit Domercq ◽  
Simon C. Jones ◽  
Stephen Barlow ◽  
...  
Keyword(s):  
Charge Carrier ◽  
Carrier Mobility ◽  
Liquid Crystalline ◽  
Room Temperature ◽  
Charge Carrier Mobility ◽  
High Charge ◽  
High Charge Carrier Mobility

scholarly journals PSEUDO-GAP FEATURES OF INTRINSIC TUNNELING IN (HgBr2)-Bi2212 SINGLE CRYSTALS

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3758-3763 ◽  
Author(s):  
AUGUST YURGENS ◽  
DAG WINKLER ◽  
TORD CLAESON ◽  
SEONG-JU HWANG ◽  
JIN-HO CHOY
Keyword(s):  
Temperature Dependence ◽  
Single Crystals ◽  
Room Temperature ◽  
Unit Cell ◽  
Superconducting Gap ◽  
Axis Direction ◽  
Temperature Range ◽  
Dynamic Conductance

The c-axis tunneling properties of both pristine Bi2212 and its HgBr 2 intercalate have been measured in the temperature range 4.2-250 K. Lithographically patterned 7-10 unit-cell heigh mesa structures on the surfaces of these single crystals were investigated. Clear SIS-like tunneling curves for current applied in the c-axis direction have been observed. The dynamic conductance d I/ d V(V) shows both sharp peaks corresponding to a superconducting gap edge and a dip feature beyond the gap, followed by a wide maximum, which persists up to a room temperature. Shape of the temperature dependence of the c-axis resistance does not change after the intercalation suggesting that a coupling between CuO 2-bilayers has little effect on the pseudogap.

NQR and Crystal Structure of 4,5-Dichloroimidazole, C3H2N2Cl2

1992 ◽  
Vol 47 (1-2) ◽  
pp. 177-181 ◽  
Author(s):  
Shi-Qi Dou ◽  
Alarich Weiss
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Unit Cell ◽  
Space Group ◽  
Temperature Range ◽  
Temperature Coefficients ◽  
Group D

AbstractThe two line 35Cl NQR spectrum of 4,5-dichloroimidazole was measured in the temperature range 77≦ T/K ≦ 389. The temperature dependence of the NQR frequencies conforms with the Bayer model and no phase transition is indicated in the curves v ( 35Cl)= f(T). Also the temperature coefficients of the 35Cl NQR frequencies are "normal". At 77 K the 35Cl NQR frequencies are 37.409 MHz and 36.172 MHz and at 389 K 35.758 MHz and 34.565 MHz. The compound crystallizes at room temperature with the tetragonal space group D44-P41212, Z = 8 molecules per unit cell; at 295 K : a = 684.2(5) pm, c = 2414.0(20) pm. The relations between the crystal structure and the NQR spectrum are discussed.

Gold nanoresistors with near-constant resistivity in the cryogenic-to-room temperature range

2011 ◽  
Vol 110 (2) ◽  
pp. 023303 ◽  
Author(s):  
M. M. A. Yajadda ◽  
I. Levchenko ◽  
K. Ostrikov
Keyword(s):  
Room Temperature ◽  
Temperature Range

About the Electrical Activation of 1×1020 cm-3 Ion Implanted Al in 4H-SiC at Annealing Temperatures in the Range 1500 - 1950°C

2018 ◽  
Vol 924 ◽  
pp. 333-338 ◽  
Author(s):  
Roberta Nipoti ◽  
Alberto Carnera ◽  
Giovanni Alfieri ◽  
Lukas Kranz
Keyword(s):  
Activation Energy ◽  
Sheet Resistance ◽  
Annealing Time ◽  
Thermal Activation ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Thermal Activation Energy ◽  
Electrical Activation ◽  
Temperature Range ◽  
Annealing Temperatures

The electrical activation of 1×1020cm-3implanted Al in 4H-SiC has been studied in the temperature range 1500 - 1950 °C by the analysis of the sheet resistance of the Al implanted layers, as measured at room temperature. The minimum annealing time for reaching stationary electrical at fixed annealing temperature has been found. The samples with stationary electrical activation have been used to estimate the thermal activation energy for the electrical activation of the implanted Al.

Photoluminescence of Ca4Ga2S7:Eu2+ in wide excitation intensity and temperature range

2021 ◽  
pp. 2150392
Author(s):  
B. D. Urmanov ◽  
M. S. Leanenia ◽  
G. P. Yablonskii ◽  
O. B. Taghiyev ◽  
K. O. Taghiyev ◽  
...  
Keyword(s):  
Room Temperature ◽  
Laser Excitation ◽  
Excitation Intensity ◽  
Temperature Measurements ◽  
Constant Time ◽  
Photoluminescence Properties ◽  
Temperature Range ◽  
Chalcogenide Semiconductors ◽  
Time Frames

Photoluminescence properties of [Formula: see text] chalcogenide semiconductors have been studied under the impulse laser excitation in the range of 10–105 W/cm2 at room temperature. This study has shown that as a result of excitation, photoluminescence of [Formula: see text] is characterized by the emission in the interval of 450–575 nm with significant domination in the spectra line at 660 nm. Photoluminescence of [Formula: see text] quenches at wavelengths of 560 nm and 660 nm with constant time frames 258 ns and 326 ns, respectively. Moreover, the temperature measurements of photoluminescence were performed on the samples in the temperature range of 10–300 K.

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