scholarly journals Chiral 1,2-Subnaphthalocyanines

2021 ◽  
Author(s):  
Soji Shimizu ◽  
Akito Miura ◽  
Tebello Nyokong ◽  
Samson Khene ◽  
Nagao Kobayashi
Keyword(s):  
Diffraction Analysis ◽  
Magnetic Circular Dichroism ◽  
Small Variation ◽  
Soret Band ◽  
Chiral Molecules ◽  
X Ray Diffraction ◽  
Enantiomerically Pure ◽  
X Ray ◽  
First Time ◽  
The Relationship

<p>Following the first suggestion of inherent molecular chirality in asymmetrically substituted subphthalocyanines by Torres and co-workers in 2000, elucidation of the relationship between structure and chirality has become an important issue. However, separation of the enantiomers has been prevented by the low solubility of the molecules synthesized to date, and it has not been possible to link the CD signs and intensities to their absolute structures. Recently, we observed that 1,2-subnaphthalocyanines possess two diastereomers with respect to the arrangement of the naphthalene moieties and that these novel chiral molecules exhibit moderate solubility in common organic solvents. This has enabled us to separate all of the diastereomers and enantiomers. The two diastereomers have been completely characterized by NMR spectroscopy and X-ray diffraction analysis. The absorption and magnetic circular dichroism spectra, together with theoretical calculation, reveal a small variation in the frontier molecular orbitals of the 1,2-subnaphthalocyanines compared with conventional subphthalocyanines, except for destabilization of the HOMO–3, which results in a characteristic absorption in the Soret band region. The chirality of 1,2-subnaphthalcyanines, including the CD signs and intensities, is discussed in detail for the first time with enantiomerically pure molecules whose absolute structures have been elucidated by single-crystal X-ray diffraction analysis.</p>

scholarly journals Chiral 1,2-Subnaphthalocyanines

2021 ◽  
Author(s):  
Soji Shimizu ◽  
Akito Miura ◽  
Tebello Nyokong ◽  
Samson Khene ◽  
Nagao Kobayashi
Keyword(s):  
Diffraction Analysis ◽  
Magnetic Circular Dichroism ◽  
Small Variation ◽  
Soret Band ◽  
Chiral Molecules ◽  
X Ray Diffraction ◽  
Enantiomerically Pure ◽  
X Ray ◽  
First Time ◽  
The Relationship

<p>Following the first suggestion of inherent molecular chirality in asymmetrically substituted subphthalocyanines by Torres and co-workers in 2000, elucidation of the relationship between structure and chirality has become an important issue. However, separation of the enantiomers has been prevented by the low solubility of the molecules synthesized to date, and it has not been possible to link the CD signs and intensities to their absolute structures. Recently, we observed that 1,2-subnaphthalocyanines possess two diastereomers with respect to the arrangement of the naphthalene moieties and that these novel chiral molecules exhibit moderate solubility in common organic solvents. This has enabled us to separate all of the diastereomers and enantiomers. The two diastereomers have been completely characterized by NMR spectroscopy and X-ray diffraction analysis. The absorption and magnetic circular dichroism spectra, together with theoretical calculation, reveal a small variation in the frontier molecular orbitals of the 1,2-subnaphthalocyanines compared with conventional subphthalocyanines, except for destabilization of the HOMO–3, which results in a characteristic absorption in the Soret band region. The chirality of 1,2-subnaphthalcyanines, including the CD signs and intensities, is discussed in detail for the first time with enantiomerically pure molecules whose absolute structures have been elucidated by single-crystal X-ray diffraction analysis.</p>

scholarly journals Valence self-regulation of sulfur in nanoclusters

2019 ◽  
Vol 5 (11) ◽  
pp. eaax7863 ◽  
Author(s):  
Xi Kang ◽  
Fengqing Xu ◽  
Xiao Wei ◽  
Shuxin Wang ◽  
Manzhou Zhu
Keyword(s):  
Mass Spectrometry ◽  
Single Crystal ◽  
Diffraction Analysis ◽  
Valence State ◽  
Self Regulation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Capping Ligands ◽  
First Time

The valence self-regulation of sulfur from the “−2” valence state in thiols to the “−1” valence state in hydroxylated thiolates has been accomplished using the Pt1Ag28 nanocluster as a platform—the first time that the “−1” valent sulfur has been detected as S−1. Two previously unknown nanoclusters, Pt1Ag28(SR)20 and Pt1Ag28(SR)18(HO-SR)2 (where SR represents 2-adamantanethiol), have been synthesized and characterized—in the latter nanocluster, the presence of hydroxyl induces the valence regulation of two special S atoms from “−2” (in SR) to “−1” valence state in the HO-S(Ag)R. Because of the contrasting nature of the capping ligands in these two nanoclusters [i.e., only SR in Pt1Ag28(SR)20 or both SR- and HO-SR- in Pt1Ag28(SR)18(HO-SR)2], they exhibit differing shell architectures, even though their cores (Pt1Ag12) are in the same icosahedral configuration. Single-crystal x-ray diffraction analysis revealed their 1:1 cocrystallization, and mass spectrometry verified the presence of hydroxyls on Pt1Ag28(SR)18(HO-SR)2.

Strength of Metals in the Light of Modern Physics

1936 ◽  
Vol 40 (309) ◽  
pp. 586-621 ◽  
Author(s):  
H. J. Gough ◽  
W. A. Wood
Keyword(s):  
Atomic Structure ◽  
Internal Stresses ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Modern Physics ◽  
Correct Understanding ◽  
Development Methods ◽  
First Time ◽  
The Relationship

SummaryThe strengths of the metals at present available to industry are of especial importance to the aeronautical engineer who is also in a position to appreciate the need for greatly improved materials, the absence of which often places restriction on much needed developments. Although the materials of the future may become available by the somewhat fortuitous development methods at present employed, it is undeniable that greatly accelerated developments would result if a correct understanding was obtained of the fundamental characteristics of the cohesion and fracture of metals, of which the former belongs to the field of the atomic physicist.It has been found possible, for the first time, to show that failure under static and fatigue stressing is associated with changes in the crystalline structure which are identical. These changes are (1) a dislocation of the initially perfect grains into large components which vary in orientation from that of the internal grain by amounts up to about 2°,(2) the formation of “crystallites,” approximately 10-4 to 10-5 cm. in size, whose orientation varies widely from that of the original grains, and (3) the presence of severe internal stresses in the crystallites. At fracture, whatever the type of applied stressing, the whole of the specimen behaves to the X-ray beam as a medium of crystallites showing marked lattice distortion and oriented completely at random. X-ray diffraction methods are shown to distinguish clearly between the effects of the application of safe and unsafe ranges of stress; the first method that has been successful in this respect.In order to show the relationship between the new work described and previous work dealing with the use of X-rays in studying the deformation characteristics of metals, a preliminary section of the paper deals with cold-rolling and drawing. A survey is also presented of the present position regarding strength and atomic structure, together with references to various theories regarding the imperfections of crystals as encountered in practice. An introductory section describes briefly the atomic structure of metals, as revealed by X-rays.

Powder X-ray diffraction analysis of the ferroelectric liquid crystal with a 2-methylbutoxypropionate unit as a function of temperature

2003 ◽  
Vol 18 (4) ◽  
pp. 293-295 ◽  
Author(s):  
L. Dobiášová ◽  
H. Šíchová ◽  
V. Valvoda
Keyword(s):  
Liquid Crystal ◽  
Diffraction Analysis ◽  
Small Variation ◽  
Ferroelectric Liquid Crystal ◽  
X Ray Diffraction ◽  
Layer Spacing ◽  
X Ray ◽  
Temperature Range ◽  
Liquid Crystal Material ◽  
Intermolecular Distances

The ferroelectric liquid crystal material [4-[(4-methyloxyfenyl) carbonyloxyl] bifenyl-4′-yl]-(S)-2-methylbutoxypropionate containing a lateral methyl group on the aromatic ring of the alkoxybenzoate unit and two chiral carbons has been investigated by X-ray powder diffraction analysis at the 28 °C–105 °C temperature range. On cooling through the SmC temperature range, the layer spacing decreases from 28.3 to 27.7 Å with a small variation of average intermolecular distances. Lattice parameters of tetragonal and monoclinic crystalline phases occurring at lower temperatures have been determined.

scholarly journals Структура и сегнетоэлектрические свойства гетероэпитаксиальных тонких пленок NaNbO-=SUB=-3-=/SUB=-, полученных методом RF-катодного распыления

2020 ◽  
Vol 46 (2) ◽  
pp. 15
Author(s):  
А.В. Павленко ◽  
Д.В. Стрюков ◽  
Н.В. Тер-Оганесян
Keyword(s):  
Thin Films ◽  
Diffraction Analysis ◽  
Single Phase ◽  
Oxygen Atmosphere ◽  
Cell Deformation ◽  
X Ray Diffraction ◽  
Cathode Sputtering ◽  
Ferroelectric State ◽  
X Ray ◽  
First Time

For the first time, thin films of NaNbO3 on a MgO(001) substrate, on which a SrRuO3 layer was previously deposited, were obtained by RF cathode sputtering in an oxygen atmosphere. According to x-ray diffraction analysis the films are single phase and single-crystalline. The lattice parameters in the tetragonal approximation for the NaNbO3 and SrRuO3 layers were: с(NaNbO3) = 0.3940(1) nm, a(NaNbO3) = 0.389(1) nm; с(SrRuO3) = 0.4004(1) nm, a(SrRuO3) = 0.392(3) nm. The unit cell deformation for NaNbO3 was ε33 = 0.007, ε11 = 0.002. Dielectric and piezoelectric measurements indicate that the films are in a ferroelectric state.

scholarly journals Thermodynamic Functions of Fe3B Borides

2019 ◽  
Vol 20 (2) ◽  
pp. 139-143
Author(s):  
N.Yu. Filonenko ◽  
O.M. Galdina ◽  
A.V. Kochenov
Keyword(s):  
Diffraction Analysis ◽  
Thermodynamic Functions ◽  
Boron Content ◽  
Liquidus Line ◽  
Complete Suppression ◽  
X Ray Diffraction ◽  
Cast State ◽  
X Ray ◽  
Eutectic Colony ◽  
First Time

In this work we study the structural properties of hypoeutectic and hypereutectic Fe-B alloys, depending on the temperature of heating above the liquidus line and the cooling rate. Experiments were carried out for the Fe-B system alloys with boron content of 2.0 - 4.5 % (wt.), the rest is iron. To determine physical properties of the alloys microstructural and X-ray diffraction analysis were used. It is shown that overheating of the molten alloy to 150 K above the liquidus line and aftercooling leads to complete suppression of the formation of primary iron crystals in the hypoeutectic alloys and partially to suppression of Fe2B formation in the hypereutectic alloys of the Fe-B system. For the first time it is shown that heating of Fe-B hypoeutectic alloys to 150 K above the liquidus line and cooling with a rate of 103 K/s lead to formation of Fe3B boride in as-cast state, which was present in the eutectic colony.

Structure and ionic conductivity of the octahydrate of tetralithium salt of calix[4]arenesulfonic acid

2021 ◽  
Author(s):  
Anna Pisareva ◽  
Gennady V. Shilov ◽  
Alexander Karelin ◽  
Rostislav Pisarev ◽  
Nadezhghda Bukun ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ionic Conductivity ◽  
Diffraction Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Arenesulfonic Acid ◽  
First Time

Octahydrate of tetralithium salt of calix[4]sarenesulfonic acid was isolated for the first time The crystal structure of salt was determined by X-ray diffraction analysis. Compound crystallized in triclinic syngony, P-1,...

scholarly journals 5α,8α-Epidioxysterols from a Formosan Sponge, Axinyssa sp

2013 ◽  
Vol 8 (11) ◽  
pp. 1934578X1300801
Author(s):  
Tzu-Rong Su ◽  
Kai-Ju Liang ◽  
Michael Y. Chiang ◽  
Mei-Chin Lu ◽  
Yu-Jen Wu ◽  
...  
Keyword(s):  
Single Crystal ◽  
Diffraction Analysis ◽  
Cell Lines ◽  
Cancer Cell ◽  
Absolute Configuration ◽  
Cancer Cell Lines ◽  
Spectroscopic Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Time

One new 5α,8α-epidioxysterol, 3-acetylaxinysterol (1), along with one known sterol, axinysterol (2), were isolated from a Formosan sponge, Axinyssa sp.. The structures of the compounds were determined by spectroscopic methods and the absolute configuration of 2 was further confirmed by single-crystal X-ray diffraction analysis for the first time. Compound 2 exhibited significant cytotoxicity against K562 and Molt 4 cancer cell lines.

scholarly journals Isolation and Identification of Cyclooctasulfur From the Octocoral Sinularia humilis (van Ofwegen, 2008)

2021 ◽  
Vol 16 (9) ◽  
pp. 1934578X2110406
Author(s):  
Jhao-Syuan Zeng ◽  
Yi-Hung Liu ◽  
San-Nan Yang ◽  
Su-Ying Chien ◽  
Zhi-Hong Wen ◽  
...  
Keyword(s):  
Single Crystal ◽  
Diffraction Analysis ◽  
Marine Invertebrate ◽  
X Ray Diffraction ◽  
Isolation And Identification ◽  
Chemical Examination ◽  
X Ray ◽  
First Time

Chemical examination of the octocoral Sinularia humilis, collected in the waters of Taiwan, led to the isolation of S8 (1). Its structure was determined by a single-crystal x-ray diffraction analysis and this is the first time that S8 has been reported from a marine invertebrate.

The Synthesis and Structural Characterization of Peralkylated Triguanide Superbases

2014 ◽  
Vol 67 (7) ◽  
pp. 1129 ◽  
Author(s):  
Vjekoslav Štrukil ◽  
Edislav Lekšić ◽  
Ernest Meštrović ◽  
Mirjana Eckert-Maksić
Keyword(s):  
Diffraction Analysis ◽  
Gas Phase ◽  
Structural Characterization ◽  
Positive Charge ◽  
Coupling Reaction ◽  
Chloride Salt ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Time

Organic superbases derived from a peralkylated triguanide framework have been synthesized in a coupling reaction between monosubstituted guanidines and a Vilsmeier salt. Single crystal X-ray diffraction analysis of the chloride salt allowed the structural characterization of the benzyl derivative for the first time and revealed an effective delocalization of the positive charge despite significant distortion of the triguanide cation planarity. With the calculated gas phase basicity ranging from 262 to 265 kcal mol–1 and pKa values in acetonitrile between 28 and 30, these compounds have been evaluated as potential organocatalysts in the transesterification reaction of vegetable oil.

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