Phase transitions in adamantane derivatives: 1-fluoroadamantane

1991 ◽  
Vol 69 (11) ◽  
pp. 1758-1765 ◽  
Author(s):  
Nancy T. Kawai ◽  
Denis F. R. Gilson ◽  
Ian S. Butler
Keyword(s):  
Phase Transition ◽  
Raman Spectroscopy ◽  
High Pressures ◽  
Spectroscopic Studies ◽  
Phase Behaviour ◽  
Slow Heating ◽  
Adamantane Derivatives ◽  
Scanning Calorimetry ◽  
Line Narrowing ◽  
Infrared And Raman Spectroscopy

The solid-state phase behaviour of 1-fluoroadamantane (1-C10H15F) has been investigated by differential scanning calorimetry, and by infrared and Raman spectroscopy. The phase transition occurs at 227 K on cooling and at 231 K upon heating, with average ΔHt and ΔSt of 1.65 kJ mol−1 and 7.3 J K−1 mol−1. The transition was also apparent in the low-temperature IR and Raman spectra by a sudden line narrowing, and characteristic spectral features of each phase were identified. Both phases I and II were disordered, and further cooling of phase II resulted in the formation of a glass. Attempts to induce a glass transition (predicted to occur at ~90 K) by slow heating were unsuccessful. Vibrational spectroscopic studies at high pressures showed a phase transition at 3.3 ± 1.0 kbar, upon compression. The phases formed under pressure were the same as those induced by lowering temperature. Key words: high-pressure infrared and Raman spectroscopy, phase transition, plastic crystal, orientational disorder.

The Fluorescence of Diamond and Raman Spectroscopy at High Pressures Using a New Design of Diamond Anvil Cell

1973 ◽  
Vol 27 (5) ◽  
pp. 377-381 ◽  
Author(s):  
D. M. Adams ◽  
S. J. Payne ◽  
K. Martin
Keyword(s):  
Raman Spectroscopy ◽  
Diamond Anvil Cell ◽  
High Pressures ◽  
Fluorescence Emission ◽  
Type I ◽  
High Pressure Cell ◽  
Scattering Geometry ◽  
Infrared And Raman Spectroscopy ◽  
Bond Stretching ◽  
Diamond Anvil

A new design of diamond anvil high pressure cell suitable for use in infrared and Raman spectroscopy is described. Its performance is demonstrated with particular reference to the pressure dependence of the infrared spectrum of K2PtCl6 and the Raman spectrum of W(CO)6. In contrast to earlier reports, in which forward scattering geometry was used, this design of cell is shown to be very suitable for Raman use in the 180° excitation mode. However, severe limitations are imposed by the fluorescence emission of diamond and of sapphire. Conditions under which the cell can be used for Raman work are summarized. New fluorescence and Raman features are reported for diamond. In particular, a band at 1730 cm−1 is characteristic of type I stones and may be due to C to N bond stretching at defect centers.

SAXS Study of Selected Cationic Surfactant Influence on the DSPC-Based Model Phospholipid System

2007 ◽  
Vol 130 ◽  
pp. 257-262
Author(s):  
Maciej Kozak ◽  
Ludwik Domka ◽  
Stefan Jurga
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Small Angle ◽  
Phase Behaviour ◽  
Lamellar Phase ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering ◽  
Hydrocarbon Chains ◽  
Main Transition

The phase behaviour of lipid bilayer systems prepared with 1,2-distearoyl-sn-glycero-3- phosphocholine (DSPC) with dodecyldimethyl(benzyloxymethyl)ammonium chloride (BzMDDAC) (at concentrations 0.1, 1 and 5%) has been studied by small angle X-ray scattering and differential scanning calorimetry. The SAXS and DSC results of the hydrated 10% DSPC revealed one typical phase transition corresponding to melting of the hydrocarbon chains at 55 °C. In the system of 10% DSPC - 0.1 % BzMDDAC the main transition was somewhat shifted towards lower temperatures, while at 1% concentration of BzMDDAC in the mixture, the lamellar phase disappeared, as evidenced by SAXS and DSC. The increase in BzMDDAC concentration to 5% in the mixture with 10% DSPC resulted in formation of a new lamellar phase.

Spectroscopic studies of the phase transition in ammonia borane: Raman spectroscopy of single crystal NH3BH3 as a function of temperature from 88to330K

2008 ◽  
Vol 128 (3) ◽  
pp. 034508 ◽  
Author(s):  
Nancy J. Hess ◽  
Mark E. Bowden ◽  
Vencislav M. Parvanov ◽  
Chris Mundy ◽  
Shawn M. Kathmann ◽  
...  
Keyword(s):  
Phase Transition ◽  
Raman Spectroscopy ◽  
Single Crystal ◽  
Ammonia Borane ◽  
Spectroscopic Studies

Far-infrared and Raman spectroscopy of the phase transition in CsCuCl3

1981 ◽  
Vol 10 (1) ◽  
pp. 187-193 ◽  
Author(s):  
J. Petzelt ◽  
I. Gregora ◽  
V. Vorlíček ◽  
J. Fousek ◽  
B. Březina ◽  
...  
Keyword(s):  
Phase Transition ◽  
Raman Spectroscopy ◽  
Far Infrared ◽  
Infrared And Raman Spectroscopy

scholarly journals Applications of vibrational spectroscopy in the study of flavin-based photoactive proteins

2011 ◽  
Vol 25 (6) ◽  
pp. 261-269 ◽  
Author(s):  
Jiang Li ◽  
Teizo Kitagawa
Keyword(s):  
Signal Transduction ◽  
Raman Spectroscopy ◽  
Blue Light ◽  
Reaction Mechanisms ◽  
Flavin Adenine Dinucleotide ◽  
Spectroscopic Studies ◽  
Biological Functions ◽  
Light Sensing ◽  
Infrared And Raman Spectroscopy ◽  
Sensitive Tool

Flavin cofactor is known to perform diverse biological functions. Recently, its role as a photoreceptor has been identified. So far, three classes of photoactive flavoproteins have been recognized: phototropin with LOV (Light, Oxygen and Voltage) domain, blue light sensory protein with BLUF (Blue Light sensing Using Flavin adenine dinucleotide) domain and photolyase/cryptochrome protein with PHR (Photolyase Homology Region) domain. Photochemistry of flavin is the key to unravel the reaction mechanisms of photoactive flavoproteins in their biological functions such as DNA repair or signal transduction. Vibrational (Infrared and Raman) spectroscopy is a useful and sensitive tool to investigate the photochemistry of flavin in protein environments and has significantly contributed to elucidate the reaction mechanisms of these photoactive proteins. This study will survey recent advances in vibrational spectroscopic studies on this topic and remaining questions to be answered.

Differential scanning calorimetry and X-ray diffraction studies of a series of synthetic β-D-galactosyl diacylglycerols

1991 ◽  
Vol 69 (12) ◽  
pp. 863-867 ◽  
Author(s):  
D. A. Mannock ◽  
R. N. McElhaney
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Phase Behaviour ◽  
Lipid Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Phase Transition Temperatures ◽  
Bonding Properties ◽  
Lower Temperature

We have investigated the physical properties of a homologous series of synthetic, saturated 1,2-di-O-acyl-3-O-(β-D-galactopyranosyl)-sn-glycerols using calorimetry and X-ray diffraction. Unannealed aqueous dispersions of these compounds exhibit a lower temperature, moderately energetic, chain-melting (Lβ/Lα phase transition and a higher temperature, weakly energetic, bilayer/nonbilayer phase transition. On annealing below the Lβ/Lα phase transition, the Lβ phase converts to an LC phase, which may undergo a highly energetic LC/Lα or LC/HII phase transition at very high temperatures on reheating. The temperatures of these phase transitions are higher than those seen in the corresponding α- and β-D-glucosyl diacylglycerols. However, the Lβ/Lα and bilayer/nonbilayer phase transition temperatures of the β-D-galactosyl diacylglycerols are lower than those of the corresponding diacyl phosphatidylethanolamines. These observations are discussed in terms of the hydration and hydrogen bonding properties of their respective headgroups.Key words: differential scanning calorimetry, low-angle x-ray diffraction, glycolipids, galactolipids, lipid phase behaviour.

Low-temperature phase transition in glycine–glutaric acid co-crystals studied by single-crystal X-ray diffraction, Raman spectroscopy and differential scanning calorimetry

2012 ◽  
Vol 68 (3) ◽  
pp. 287-296 ◽  
Author(s):  
Boris A. Zakharov ◽  
Evgeniy A. Losev ◽  
Boris A. Kolesov ◽  
Valeri A. Drebushchak ◽  
Elena V. Boldyreva
Keyword(s):  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Raman Spectroscopy ◽  
Single Crystal ◽  
Glutaric Acid ◽  
Group Symmetry ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray

The occurrence of a first-order reversible phase transition in glycine–glutaric acid co-crystals at 220–230 K has been confirmed by three different techniques – single-crystal X-ray diffraction, polarized Raman spectroscopy and differential scanning calorimetry. The most interesting feature of this phase transition is that every second glutaric acid molecule changes its conformation, and this fact results in the space-group symmetry change from P21/c to P\bar 1. The topology of the hydrogen-bonded motifs remains almost the same and hydrogen bonds do not switch to other atoms, although the hydrogen bond lengths do change and some of the bonds become inequivalent.

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