Search results for "Single Crystals"
showing 10 items of 12 documents
High-Pressure Softening of the Out-of-Plane A2u(Transverse-Optic) Mode of Hexagonal Boron Nitride Induced by Dynamical Buckling
2019
We investigate the highly anisotropic behavior of the in-plane and out-of-plane infrared-active phonons of hexagonal boron nitride by means of infrared reflectivity and absorption measurements under high pressure. Infrared reflectivity spectra at normal incidence on high-quality single crystals show strict fulfillment of selection rules and an unusually long E1u[transverse-optic (TO)] phonon lifetime. Accurate values of the dielectric constants at ambient pressure ϵ0= 6.96, ϵ∞= 4.95, ϵ 0= 3.37, and ϵ∞ = 2.84 have been determined from fits to the reflectivity spectra. The out-of-plane A2u phonon reflectivity band is revealed in measurements on an inclined facet, and absorption measurements a…
Crystal structure of 4,6-O-ethylidene-N-(2-hydroxybenzylidene)-β-D-glucopyranosylamine
2002
4,6-O-Ethylidene-N-(2-hydroxybenzylidene)-β-D-glucopyranosylamine was synthesized and characterized using analytical, spectral and single-crystal X-ray diffraction methods. The anomeric nature of the saccharide moiety was proposed based on 1H NMR studies and was confirmed by the crystal structure. The lattice structure of this compound was compared with that of its analogues.
Solvent induced single-crystal to single-crystal structural transformation and concomitant transmetalation in a 3D cationic Zn(II)-framework.
2015
A 3D cationic Zn(II) framework, based on Zn2(CO2)4 paddle-wheel secondary building units (SBUs) and Zn16(CO2)32 polyhedral supramolecular building blocks (SBBs), has been synthesized. At room temperature, the framework undergoes guest solvent triggered reversible structural transformation and concomitant Zn(II) to Cu(II) transmetalation in a single-crystal to single-crystal fashion.
Effect of Ga content on luminescence and defects formation processes in Gd3(Ga,Al)5O12:Ce single crystals
2018
The work was supported by the Institutional Research Funding IUT02-26 of the Estonian Ministry of Education and Research and the project 16-15569S of the Czech Science Foundation.
Formation of a novel ferromagnetic end-to-end cyanate bridged homochiral helical copper(ii) Schiff base complex via spontaneous symmetry breaking
2014
A homochiral helical coordination polymer of copper(II) has been synthesized using achiral precursors via spontaneous symmetry breaking and has been confirmed by single crystal X-ray diffraction and solid-state CD spectroscopy. The variable temperature magnetic measurements indicate the presence of weak ferromagnetic exchange interactions mediated by end-to-end cyanate bridges (J = +0.12 cm(-1)).
Crystal structure of 5-(4-tert-butoxyphenyl)-3-(4-n-octyloxyphenyl)-4,5-dihydroisoxazole
2019
The molecule of the title compound, C27H37NO3, was prepared by [3 + 2] 1,3-dipolar cycloaddition of 4-n-octylphenylnitrile oxide and 4-tert-butoxystyrene, the latter compound being a very useful intermediate to the synthesis of liquid-crystalline materials. In the molecule, the benzene rings of the n-octyloxyphenyl and tert-butoxyphenyl groups form dihedral angles of 2.83 (7) and 85.49 (3)°, respectively, with the mean plane of the isoxazoline ring. In the crystal, molecules are linked by weak C—H...O hydrogen interactions into chains running parallel to the b axis.
Coordination Complexes of a Neutral 1,2,4-Benzotriazinyl Radical Ligand: Synthesis, Molecular and Electronic Structures, andMagnetic Properties
2015
A series of d-block metal complexes of the recently reported coordinating neutral radical ligand 1-phenyl-3-(pyrid-2-yl)-1,4-dihydro-1,2,4-benzotriazin-4-yl (1) was synthesized. The investigated systems contain the benzotriazinyl radical 1 coordinated to a divalent metal cation, MnII, FeII, CoII, or NiII, with 1,1,1,5,5,5-hexafluoroacetylacetonato (hfac) as the auxiliary ligand of choice. The synthesized complexes were fully characterized by single-crystal X-ray diffraction, magnetic susceptibility measurements, and electronic structure calculations. The complexes [Mn(1)(hfac)2] and [Fe(1)(hfac)2] displayed antiferromagnetic coupling between the unpaired electrons of the ligand and the meta…
Nature-Inspired Effects of Naturally Occurring Trace Element-Doped Hydroxyapatite Combined with Surface Interactions of Mineral-Apatite Single Crysta…
2022
Innovative engineering design for biologically active hydroxyapatites requires enhancing both mechanical and physical properties, along with biocompatibility, by doping with appropriate chemical elements. Herein, the purpose of this investigation was to evaluate and elucidate the model of naturally occurring hydroxyapatite and the effects of doped trace elements on the function of normal human fibroblasts, representing the main cells of connective tissues. The substrates applied (geological apatites with hexagonal prismatic crystal habit originated from Slyudyanka, Lake Baikal, Russia (GAp) and from Imilchil, The Atlas Mountains, Morocco (YAp)) were prepared from mineral natural apatite wit…
2-(N,N-Diethylaminomethyl)-6,7-trihydroquinolinyl-8-ylideneamine-Ni(ii) chlorides: application in ethylene dimerization and trimerization
2020
A series of Ni(II) complexes with the general formula [2-((NEt2)Me)-8-{N(Ar)}C9H8N]NiCl2, where Ar = 2,6-Me2C6H3 in Ni1, 2,6-Et2C6H3 in Ni2, 2,6-i-Pr2C6H3 in Ni3, 2,4,6-Me3C6H2 in Ni4, 2,6-Et2-4-MeC6H2 in Ni5, and 2,4,6-t-Bu3C6H2 in Ni6, has been prepared using a one-pot reaction of 2-(N,N-diethylaminomethyl)-6,7-dihydroquinolin-8(5H)-one with the corresponding aniline and nickel dichloride hexahydrate. The resultant complexes were characterized using elemental analysis and FT-IR spectroscopy, while the mononuclear Ni1 and Ni3 were also the subject of single-crystal X-ray diffraction study. On activation with MMAO, the complexes Ni1–Ni6 displayed good activity in ethylene oligomerization, f…
Lattice Dynamics Study of HgGa2Se4 at High Pressures
2013
We report on Raman scattering measurements in mercury digallium selenide (HgGa2Se4) up to 25 GPa. We also performed, for the low-pressure defect-chalcopyrite structure, lattice-dynamics ab initio calculations at high pressures which agree with experiments. Measurements evidence that the semiconductor HgGa2Se4 exhibits a pressure-induced phase transition above 19 GPa to a previously undetected structure. This transition is followed by a transformation to a Raman-inactive phase above 23.4 GPa. On downstroke from 25 GPa until 2.5 GPa, a broad Raman spectrum was observed, which has been attributed to a fourth phase, and whose pressure dependence was followed during a second upstroke. Candidate …