Syntheses and Substituent Effects on the Properties of Unsymmetrical Photochromic Diarylethenes Bearing a Benzothiophene Unit

2009 ◽  
Vol 62 (5) ◽  
pp. 464 ◽  
Author(s):  
Shouzhi Pu ◽  
Min Li ◽  
Gang Liu ◽  
Zhanggao Le
Keyword(s):  
Crystalline Phase ◽  
Substituent Effects ◽  
Cyclic Voltammogram ◽  
X Ray Diffraction ◽  
Strong Electron ◽  
X Ray ◽  
Remarkable Effect ◽  
Photostationary State ◽  
Closed Ring ◽  
Electron Withdrawing Substituents

Photochromic unsymmetrical diarylethenes 1a–5a that bear different electron-donating or electron-withdrawing substitutes have been synthesized, and the structures of 2a–5a determined by single-crystal X-ray diffraction analysis. Substituent effects on their optoelectronic properties, including photochromism, fluorescence, and electrochemical properties are investigated in detail. The strong electron-donating substituents have effective contributions to the absorption maxima of the closed-ring isomers and the molar coefficients, whereas the electron-withdrawing substituents can shift significantly the absorption maxima of the diarylethenes to a longer wavelength and increase their cyclization quantum yield. Diarylethenes 2, 3, and 4 show good photochromism both in solution and in the single crystalline phase. However, diarylethenes 5 shows no photochromism in the crystalline phase. Diarylethenes 1, 2, and 3 exhibit good fluorescent switching upon alternating irradiation with UV and visible light, and their fluorescent conversions in the photostationary state are all larger than 80% in hexane. In addition, cyclic voltammogram tests show that different electron-donating and electron-withdrawing substituents have a remarkable effect on the electrochemical behaviours of these diarylethenes.

Eine elektrochemische und strukturelle Studie an den Eisensilylamiden Fe[N(SiMe3)2]2 und Fe[N(SiMe3)2]3 / An Electrochemical and Structural Study of the Iron Silylamides Fe[N(SiMe3)2]2 and Fe[N(SiMe3)2]3

2012 ◽  
Vol 67 (6) ◽  
pp. 549-556 ◽  
Author(s):  
Günter Margraf ◽  
Frauke Schödel ◽  
Inge Sänger ◽  
Michael Bolte ◽  
Matthias Wagner ◽  
...  
Keyword(s):  
Cyclic Voltammogram ◽  
X Ray Diffraction ◽  
Amido Complexes ◽  
X Ray ◽  
Redox Transition ◽  
Transfer Processes ◽  
Irreversible Oxidation ◽  
Reaction Solution ◽  
Reversible Redox ◽  
Electron Transfer Processes

The bis(trimethyl)silylamido complex Na(THF){Fe[N(SiMe3)2]3} and the disilane tBu3SiSitBu3 were obtained from the reaction of Fe[N(SiMe3)2]3 with the sodium silanide Na(THF)2[SitBu3] in a mixture of benzene and THF. Single crystals of Na(THF){Fe[N(SiMe3)2]3} suitable for X-ray diffraction were grown from the reaction solution at ambient temperature (orthorhombic, C2221, Z = 4). The solid-state structure features a contact-ion pair with two short N-Na contacts. The THF adducts {M(THF)2[N(SiMe3)2]2} reacted with 2,2´-bipyridine to give the corresponding complexes {M(2,2´bipy)[N(SiMe3)2]2} (M= Mn; Fe). Their structures (M= Fe: orthorhombic, Pca21, Z = 8; M = Mn: orthorhombic, Pbca, Z = 8) feature monomeric units. The cyclic voltammogram of Fe[N(SiMe3)2]3 revealed a reversible redox transition with the potential of -0;523 V (E½), which was assigned to the Fe(III)[N(SiMe3)2]3 → Fe(II)[N(SiMe3)2]-3 redox transition, whereas the compounds {Fe(THF)2[N(SiMe3)2]2} (Eox = -0;379 V) and {Fe(2,2´bipy)[N(SiMe3)2]2} (Eox = -0;436 V) featured irreversible oxidation waves. The related manganese bis(trimethylsilyl)amido complexes {Mn(THF)2[N(SiMe3)2]2} (Eox = -0;458 V) and {Mn(2,2´bipy)[N(SiMe3)2]2} (Eox = -0513 V) also underwent irreversibile electron transfer processes.

A Simple High-Yield Synthesis of Gallium(I) Tetrachlorogallate(III) and the Reaction of Digallium Tetrachloride Tetrahydrofuran Solvate with 1,2-Diols

2001 ◽  
Vol 56 (4-5) ◽  
pp. 337-341 ◽  
Author(s):  
Eva S. Schmidt ◽  
Annette Schier ◽  
Norbert W. Mitzel ◽  
Hubert Schmidbaur
Keyword(s):  
Crystalline Phase ◽  
Hydrogen Gas ◽  
High Yield ◽  
X Ray Diffraction ◽  
X Ray ◽  
Metal Atoms ◽  
Gallium Hydride ◽  
Hydroxy Groups ◽  
Tetrahydrofuran Solution ◽  
Analogous Product

Abstract Gallium(I) tetrachlorogallate(III) Ga[GaCU] was prepared in quantitative yield by thermal de­composition of dichlorogallane [HGaCl2]2, which is readily available from Et3SiH and [GaCl3]2. The reaction of catechol with solutions of this gallium(I) tetrachlorogallate(III) in tetrahydrofuran leads to the evolution of hydrogen gas and affords a dinuclear gallium(III) complex with penta-coordinate metal atoms chelated and bridged by mono-deprotonated catechol ligands. In the crystalline phase tetrahydrofuran molecules are hydrogen-bonded to the hydroxy groups: [Ga(1,2 -OC6H4OH)Cl2(C4H8O)]2. The reaction with pinacol also gives hydrogen and the analogous product [Ga(OCMe2CMe2OH)Cl2(C4H8O)]2. The structures of the two compounds have been determined by X-ray diffraction. A mechanism of the new reaction has been proposed which involves oxidative addition of the diol to the solvate (THF)Cl2Ga-GaCl2(THF) present in the tetrahydrofuran solution to give a gallium hydride intermediate.

Photochemical cis-trans Isomerization of 2-Substituted 9-(2-Nitroethenyl)anthracenes. X-Ray Structure Analyses of (E)- and (Z)-9-(2-Nitro-2-phenylethenyl)anthracene

1989 ◽  
Vol 42 (4) ◽  
pp. 593 ◽  
Author(s):  
HD Becker ◽  
BW Skelton ◽  
H Sorensen ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Quantum Yields ◽  
X Ray Diffraction ◽  
X Ray ◽  
Photostationary State ◽  
Trans Isomerization ◽  
Photochemical Isomerization

(E)-9-(2-Nitropropeny1)anthracene and (E)-9-(2-nitro-2-phenylethenyl)anthracene have been prepared by piperidine-catalysed condensation of 9-anthraldehyde with nitroethane and nitro(phenyl)methane, respectively. The corresponding (Z)-compounds were obtained by photochemical isomerization, quantum yields of geometrical isomerlzation being measured in cyclohexane, benzene, dichloromethane and ethanol. In virtually all solvents the (Z)-isomers are favoured at the photostationary state. The structures of (E)- and (2)-942- nitro-2-phenylethenyl)anthracene have been established by single-crystal X-ray diffraction studies.

Evolution of Crystalline Phase and Morphology of the Products Formed during the Hydrothermal Synthesis of Y2O3 Powders

2011 ◽  
Vol 189-193 ◽  
pp. 1275-1279
Author(s):  
Ying Wang ◽  
Gao Yang Zhao ◽  
Li Yuan
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Treatment ◽  
Crystalline Phase ◽  
Hydrothermal Reaction ◽  
Yttrium Nitrate ◽  
Temperature Reaction ◽  
X Ray Diffraction ◽  
Reaction Conditions ◽  
X Ray ◽  
Transmission Electron

The crystalline phase and morphology of the products formed during the synthesis of yttrium oxide via the hydrothermal treatment yttrium nitrate were characterized by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. Products with high OH/NO3ratios are formed with the increasing of hydrothermal treatment. The crystalline phases are evolved from Y2(OH)5.14(NO3)0.86•H2O toY4O(OH)9(NO3) and finally Y(OH)3. The hydrothermal reaction conditions play an important role in the synthesis of the microstructures. Results show the particle size and final morphology of samples could be controlled by reaction temperature, reaction time, and OH-concentration. Sheets, hexagonal and needle-like Y2O3powders are obtained with the hydrothermal treatment of yittrium nitrate at 180 oC to 200oC for 2-8 hours at pH 9-13.

scholarly journals Mechanistic insight of KBiQ2 (Q = S, Se) using panoramic synthesis towards synthesis-by-design

2021 ◽  
Author(s):  
Rebecca McClain ◽  
Christos D. Malliakas ◽  
Jiahong Shen ◽  
Jiangang He ◽  
Chris Wolverton ◽  
...  
Keyword(s):  
Crystalline Phase ◽  
Phase Evolution ◽  
X Ray Diffraction ◽  
Panoramic View ◽  
X Ray ◽  
Mechanistic Insight

This work uses in situ powder X-ray diffraction studies to observe crystalline phase evolution over the course of multiple K-Bi-Q (Q = S, Se) reactions, thereby constructing a “panoramic” view of each reaction from beginning to end.

Co-Firing Behavior of Co2Z Hexagonal Ferrite/Ag Internal Electrode for MLCIs

2007 ◽  
Vol 280-283 ◽  
pp. 155-158 ◽  
Author(s):  
Chun Lin Miao ◽  
Mao Wang ◽  
Zhen Xing Yue ◽  
Ji Zhou ◽  
Xue Min Cui
Keyword(s):  
Silver Electrode ◽  
Hexagonal Ferrite ◽  
Diffraction Spectrum ◽  
X Ray Diffraction ◽  
X Ray ◽  
Remarkable Effect ◽  
Sintering Additive ◽  
Electron Image ◽  
Silver Grains ◽  
Shrinkage Behavior

This paper presents the shrinkage behavior, phase transformation and interfacial character of the hexagonal ferrite/silver electrode composite. The shrinkage analysis shows apparent sintering mismatch between hexagonal ferrite ceramic and silver electrode material and improvement of the co-fired characteristics was obtained by adding appropriate amount of sintering additive. Scanning electron microscopy observations indicate that silver grains distribute uniformly in the composite. Drawn from the back-scattered (BS) electron image, no silver dispersed into the ferrite grains and there’re no obvious chemical reactions between Co2Z hexagonal ferrite and silver, which can be confirmed by X-ray diffraction spectrum. Silver induction exerts remarkable effect on the electronic properties of the composite and could increase the dielectric constant and dielectric loss to a certain extent.

Crystalline phase transformation of colloidal cadmium sulfide nanocrystals

2017 ◽  
Vol 31 (06) ◽  
pp. 1750037
Author(s):  
M. Ghali ◽  
A. M. Eissa ◽  
M. M. Mosaad
Keyword(s):  
Phase Transformation ◽  
Optical Absorption ◽  
Crystalline Phase ◽  
Growth Conditions ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Solution Ph ◽  
X Ray ◽  
Ph Values ◽  
Transmission Electron

In this paper, we give a microscopic view concerning influence of the growth conditions on the physical properties of nanocrystals (NCs) thin films made of CdS, prepared using chemical bath deposition CBD technique. We show a crystalline phase transformation of CdS NCs from hexagonal wurtzite (W) structure to cubic zincblende (ZB) when the growth conditions change, particularly the solution pH values. This effect was confirmed using X-ray diffraction (XRD), transmission electron microscopy (TEM), optical absorption and photoluminescence (PL) measurements. The optical absorption spectra allow calculation of the bandgap value, [Formula: see text], where significant increase [Formula: see text]200 meV in the CdS bandgap when transforming from Hexagonal to Cubic phase was found.

scholarly journals The Influence of Synthesis Parameters on Structural and Magnetic Properties of Iron Oxide Nanomaterials

Nanomaterials ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 85 ◽  
Author(s):  
Laura Madalina Cursaru ◽  
Roxana Mioara Piticescu ◽  
Dumitru Valentin Dragut ◽  
Ioan Albert Tudor ◽  
Victor Kuncser ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Iron Oxide ◽  
Iron Oxides ◽  
Crystalline Phase ◽  
Annealing Treatment ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Order Of Magnitude

Magnetic iron oxides have been used in biomedical applications, such as contrast agents for magnetic resonance imaging, carriers for controlled drug delivery and immunoassays, or magnetic hyperthermia for the past 40 years. Our aim is to investigate the effect of pressure and temperature on the structural, thermal, and magnetic properties of iron oxides prepared by hydrothermal synthesis at temperatures of 100–200 °C and pressures of 20–1000 bar. It has been found that pressure influences the type of iron oxide crystalline phase. Thus, the results obtained by Mössbauer characterization are in excellent agreement with X-ray diffraction and optical microscopy characterization, showing that, for lower pressure values (<100 bar), hematite is formed, while, at pressures >100 bar, the major crystalline phase is goethite. In addition, thermal analysis results are consistent with particle size analysis by X-ray diffraction, confirming the crystallization of the synthesized iron oxides. One order of magnitude higher magnetization has been obtained for sample synthesized at 1000 bar. The same sample provides after annealing treatment, the highest amount of good quality magnetite leading to a magnetization at saturation of 30 emu/g and a coercive field of 1000 Oe at 10 K and 450 Oe at 300 K, convenient for various applications.

Mullite formation from nonstoichiometric slow hydrolyzed single phase gels

1995 ◽  
Vol 10 (4) ◽  
pp. 912-917 ◽  
Author(s):  
Yong Wang ◽  
William J. Thomson
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Crystalline Phase ◽  
Single Phase ◽  
Formation Temperature ◽  
Mullite Formation ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spinel Formation

A comparative dynamic x-ray diffraction (DXRD) and differential thermal analysis (DTA) study was performed in the investigation of mullite and spinel formation from slowly hydrolyzed single phase gels with Al/Si ratios ranging from 1/1 to 14/1. Both metastable tetragonal mullite and spinel were observed to form at temperatures <1000 °C in the gels with Al/Si ratios <8/1 and mullite transformed to the orthorhombic structure at ∼1250 °C. However, at higher Al/Si ratios, spinel was the only crystalline phase detected at <1000 °C and orthorhombic mullite formed directly at temperatures >1250 °C. As the Al/Si ratio increases, both the tetragonal mullite and spinel formation temperatures decrease while the orthorhombic mullite formation temperature increases. Based on the Al/Si composition where the formation extents of tetragonal mullite and spinel were maximum, their compositions are estimated to be 2Al2O3 · SiO2 and 6A12O3 · SiO2, respectively.

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