scholarly journals The high-pressure and low-temperature structural behaviour of 2,2,2-trifluoroethanol

CrystEngComm ◽  
2019 ◽  
Vol 21 (30) ◽  
pp. 4501-4506
Author(s):  
S. A. Barnett ◽  
D. R. Allan
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Crystal Structures ◽  
Structural Behaviour

Polymorphic crystal structures have been determined for 2,2,2-trifluoroethanol by using the in situ crystallography techniques of high pressure and cryo-cooling.

scholarly journals The low-temperature and high-pressure crystal structures of cyclobutanol (C4H7OH)

2005 ◽  
Vol 61 (4) ◽  
pp. 449-454 ◽  
Author(s):  
Pamela A. McGregor ◽  
David R. Allan ◽  
Simon Parsons ◽  
Colin R. Pulham
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Crystal Structures ◽  
X Ray Diffraction ◽  
Structural Behaviour ◽  
Coordination Environment ◽  
X Ray ◽  
Alkyl Groups ◽  
Graph Set ◽  
Packing Arrangement

The low-temperature and high-pressure crystal structures of cyclobutanol (C4H7OH) have been determined using single-crystal X-ray diffraction techniques. At temperatures below 220 K, cyclobutanol crystallizes in the Aba2 space group (Z′ =  2) and its crystal structure is composed of pseudo-threefold hydrogen-bonded molecular catemers [assigned as C_2^2(4) in graph-set notation], which lie parallel to the crystallographic a axis. At a pressure of 1.3 GPa, the crystal symmetry changes to Pna21 (Z′  =  1) and the molecular catemers [expressed as C(2) in graph-set notation] adopt a pseudo-twofold arrangement. This structural behaviour is in agreement with our previous observations for phenol and its halogenated derivatives 2-chlorophenol and 4-fluorophenol, where pressure was found to favour a molecular packing more closely associated with small alkyl groups rather than that of relatively bulky alkyl groups. In addition, an examination of the molecular coordination environment in the low-temperature and high-pressure structures of cyclobutanol reveals that the change in structure on application of pressure appears to be driven by the molecules assuming a packing arrangement which more closely resembles that adopted in hard-sphere structures.

Low Temperature (4K) and High Pressure (6.5 Kbars) Crystal Structures of (TMTSF)2PF6

1985 ◽  
Vol 119 (1) ◽  
pp. 225-232 ◽  
Author(s):  
Bernard Galiois ◽  
Jacques Gaultier ◽  
Christian Hauw ◽  
Daniel Chasseau ◽  
Alain Meresse ◽  
...  
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Crystal Structures

Dimethyl-, Disilyl- and Digermylsulfide: Different Intermolecular Contacts in the Solid State

2004 ◽  
Vol 59 (6) ◽  
pp. 635-638 ◽  
Author(s):  
Norbert W. Mitzel ◽  
Udo Losehand
Keyword(s):  
Solid State ◽  
Low Temperature ◽  
Crystal Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Intermolecular Contacts

The compounds (H3C)2S, (H3Si)2S and (H3Ge)2S have been crystallised in situ on a diffractometer and their crystal structures determined by low-temperature X-ray diffraction. The molecules are present as monomers in the crystals. The aggregation of the molecules through secondary intermolecular contacts in the crystal is different: (H3C)2S is weakly associated into dimers by S···S contacts, whereas (H3Si)2S and (H3Ge)2S form Si···S and Ge···S contacts in an ice-analogous aggregation motif. Important geometry parameters are (H3C)2S: C-S 1.794(av) Å , C-S-C 99.2(1)°; (H3Si)2S: Si- S 2.143(1) Å , Si-S-Si 98.4°; (H3Ge)2S Ge-S 2.223(2) and 2.230(2) Å , Ge-S-Ge 98.2(1)◦.

High-pressure developments for resonant X-ray scattering experiments at I16

2020 ◽  
Vol 27 (2) ◽  
pp. 351-359
Author(s):  
I. Povedano ◽  
A. Bombardi ◽  
D. G. Porter ◽  
M. Burt ◽  
S. Green ◽  
...  
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
The Body ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Geometry ◽  
Diamond Anvil ◽  
Membrane Cell ◽  
Ray Scattering

An experimental setup to perform high-pressure resonant X-ray scattering (RXS) experiments at low temperature on I16 at Diamond Light Source is presented. The setup consists of a membrane-driven diamond anvil cell, a panoramic dome and an optical system that allows pressure to be measured in situ using the ruby fluorescence method. The membrane cell, inspired by the Merrill–Bassett design, presents an asymmetric layout in order to operate in a back-scattering geometry, with a panoramic aperture of 100° in the top and a bottom half dedicated to the regulation and measurement of pressure. It is specially designed to be mounted on the cold finger of a 4 K closed-cycle cryostat and actuated at low-temperature by pumping helium into the gas membrane. The main parts of the body are machined from a CuBe alloy (BERYLCO 25) and, when assembled, it presents an approximate height of 20–21 mm and fits into a 57 mm diameter. This system allows different materials to be probed using RXS in a range of temperatures between 30 and 300 K and has been tested up to 20 GPa using anvils with a culet diameter of 500 µm under quasi-cryogenic conditions. Detailed descriptions of different parts of the setup, operation and the developed methodology are provided here, along with some preliminary experimental results.

Realizing Predicted Crystal Structures at Extreme Conditions:  The Low-Temperature and High-Pressure Crystal Structures of 2-Chlorophenol and 4-Fluorophenol

2005 ◽  
Vol 5 (3) ◽  
pp. 1055-1071 ◽  
Author(s):  
Iain D. H. Oswald ◽  
David R. Allan ◽  
Graeme M. Day ◽  
W. D. Samuel Motherwell ◽  
Simon Parsons
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Crystal Structures ◽  
Extreme Conditions

In situ Raman spectroscopy of low-temperature/high-pressure transformations of H2O

2007 ◽  
Vol 126 (17) ◽  
pp. 174505 ◽  
Author(s):  
Yukihiro Yoshimura ◽  
Sarah T. Stewart ◽  
Ho-kwang Mao ◽  
Russell J. Hemley
Keyword(s):  
Raman Spectroscopy ◽  
High Pressure ◽  
Low Temperature ◽  
In Situ Raman Spectroscopy ◽  
In Situ Raman

Mélanges in southern Mexico: geochemistry and metamorphism of Las Ollas complex (Guerrero terrane)

2000 ◽  
Vol 37 (9) ◽  
pp. 1309-1320 ◽  
Author(s):  
Oscar Talavera Mendoza
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Early Cretaceous ◽  
Mineral Chemistry ◽  
White Mica ◽  
Island Arc ◽  
Southern Mexico ◽  
Calcic Amphibole ◽  
Guerrero Terrane

Las Ollas complex (LOC) is a subduction complex spatially associated with the early Cretaceous Zihuatanejo-Huetamo subterrane (Guerrero terrane) in southern Mexico. LOC tectonic mélanges compose of a stack of east-dipping, west-vergent tectonic sheets containing blocks of metabasalt, metadolerite, metagabbro, ultramafics, volcaniclastics, quartz-rich sandstone, and chert enveloped in a highly sheared clastic or serpentinitic matrix. Most igneous and igneous-derived metamorphic blocks show geochemical and isotopic features typical of island-arc tholeiitic suites: (i) low TiO2 (0.13 to 0.91%) and Zr (5 to 57 ppm) contents; (ii) high (LFSE/HFSE)N ratios; low LaN/YbN (0.5 to 4) values; and, high εNd(T) (+7.9 to +8.0) ratios. Petrographical and mineral chemistry evidence indicates that blocks underwent early recrystallization under high pressure and low temperature (HP-LT), blueschist facies conditions during subduction. Typical assemblages include blue (sodic through calco-sodic to Na-rich calcic) amphibole + lawsonite ± tremolite ± Mg-chlorite ± white mica ± albite ± quartz. Phase relations and chlorite thermometry suggest temperatures of about 200°-330o C and pressures of 5-7 kbar. It is proposed that sedimentary blocks were generated by in situ remobilization and mixing, whereas igneous blocks most probably derived from the chemically and isotopically identical Zihuatanejo island-arc suite. Our data suggest that LOC represents part of a subduction complex formed by eastward-directed subduction related with the evolution of the early Cretaceous Zihuatanejo island arc.

scholarly journals Solid-state structures of the covalent hydrides germane and stannane

2008 ◽  
Vol 64 (3) ◽  
pp. 312-317 ◽  
Author(s):  
Iain J. Maley ◽  
Daniel H. Brown ◽  
Richard M. Ibberson ◽  
Colin R. Pulham
Keyword(s):  
Low Temperature ◽  
Bond Length ◽  
Crystal Structures ◽  
Rotation Axis ◽  
Group Iv ◽  
Monoclinic Space Group ◽  
Space Group ◽  
Gas Condensation ◽  
Tetrahedral Molecules

The low-temperature crystal structures of perdeuterogermane (m.p. 108 K) and perdeuterostannane (m.p. 123 K) are reported. The structures have been characterized from low-temperature (5 K) high-resolution neutron powder diffraction experiments following sample preparation using in situ gas-condensation techniques. GeD4 crystallizes in an orthorhombic structure, space group P212121, with one molecule in the asymmetric unit, and with an average Ge—D bond length of 1.517 (3) Å. The SnD4 structure is monoclinic (space group C2/c), and the molecule is located on a twofold rotation axis with an average Sn—D bond length of 1.706 (3) Å. The crystal structures are discussed in relation to those of other tetrahedral molecules of group IV hydrides at low temperature, and evidence is presented that the crystal structure of silane, below 38 K, is isostructural with germane.

scholarly journals Intact polar lipids in the hadal seabed of the Atacama Trench point to lateral sediment transport and in situ production as key sources of labile organic matter

2021 ◽  
Author(s):  
Edgart Flores ◽  
Sebastian I. Cantarero ◽  
Paula Ruiz-Fernández ◽  
Nadia Dildar ◽  
Matthias Zabel ◽  
...  
Keyword(s):  
High Pressure ◽  
Organic Matter ◽  
Low Temperature ◽  
Unsaturated Fatty Acids ◽  
Euphotic Zone ◽  
Polar Lipids ◽  
Physiological Adaptation ◽  
Labile Organic Matter ◽  
Intact Polar Lipids

Abstract. Elevated concentrations of organic matter are found in sediments of hadal trenches relative to those found in the abyssal seabed, but the origin of such biological material remains elusive. Here, we report the composition and distribution of cell membrane intact polar lipids (IPLs) in surface sediments around the deepest points of the Atacama Trench and adjacent bathyal depths to assess and constrain the sources of labile organic matter in the hadal seabed. Multiscale bootstrap resampling of IPLs’ structural diversity and abundance indicates distinct lipid signatures in the sediments of the Atacama Trench that are more closely related to those found in bathyal sediments than to those previously reported for the upper ocean water column in the region. While the overall number of unique IPL structures in hadal sediments is limited and they contribute a small fraction of the total IPL pool, they include a high contribution of phospholipids with mono- and di-unsaturated fatty acids that are not associated with photoautotrophic sources. The diversity of labile IPLs in hadal sediments of the Atacama Trench suggests the presence of in situ microbial production and biomass that resembles traits of physiological adaptation to high pressure and low temperature, and/or the transport of labile organic matter from shallower sediment. We argue that the export of the most labile lipid component of the organic matter pool from the euphotic zone and the overlying oxygen minimum zone into the hadal sediments is neglectable. Our results contribute to the understanding of the mechanisms that control the delivery of labile organic matter to this extreme deep-sea ecosystem, whereas they provide insights into some potential physiological adaptation of the in situ microbial community to high pressure and low temperature through lipid remodeling.

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