scholarly journals Exceptionally High Temperature Spin Crossover in Amide-Functionalised 2,6-bis(pyrazol-1-yl)pyridine Iron(II) Complex Revealed by Variable Temperature Raman Spectroscopy and Single Crystal X-ray Diffraction.

2021 ◽  
Author(s):  
Max Attwood ◽  
Hiroki Akutsu ◽  
Lee Martin ◽  
Toby J Blundell ◽  
Pierre LeMagueres ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Raman Spectroscopy ◽  
High Temperature ◽  
Spin Crossover ◽  
Variable Temperature ◽  
Squid Magnetometry ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Complex Salts

The synthesis of a novel amide-functionalised 2,6-bis(pyrazol-1-yl)pyridine-4-carboxamide ligand (bppCONH2) is described. The complex salts [Fe(bppCONH2)2](BF4)2 and [Fe(bppCONH2)2](ClO4)2 were synthesised and characterised by SQUID magnetometry, differential scanning calorimetry, variable temperature Raman...

Inosose-Flüssigkristalle / Inosose Liquid Crystals

1990 ◽  
Vol 45 (7) ◽  
pp. 1084-1090 ◽  
Author(s):  
Klaus Praefcke ◽  
Bernd Kohne ◽  
Andreas Eckert ◽  
Joachim Hempel
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
High Temperature ◽  
Liquid Crystalline ◽  
Structural Features ◽  
Lyotropic Liquid Crystal ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Alkyl Chains

Six S,S-dialkyl acetals 2a-f of inosose (1), tripodal in structure, have been synthesized, characterized and investigated by optical microscopy and differential scanning calorimetry (d.s.c.). The four S,S-acetals 2c-f with sufficiently long alkyl chains are thermotropic liquid crystalline; 2 e and 2 f are even dithermomesomorphic. Each of these four inosose derivatives 2c-f exhibits monotropically a most likely cubic mesophase (MI); in addition 2e and 2f show enantiotropically a hexagonal mesophase (Hx) with a non-covalent, supramolecular H-bridge architecture. Whereas the nature of the optically isotropic mesophase MI needs further clarification the stable high temperature mesophase Hx of 2 e and 2 f has been established by a miscibility test using a sugar S,S-dialkyl acetal also tripodal in structure and with a Hx phase proved by X-ray diffraction, but in contrast to 2 with an acyclic hydrophilic part. Similarities of structural features between the Hx-phases of 2e and 2f as well as of other thermotropic and lyotropic liquid crystal systems are discussed briefly.

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.

Characterization of New Cocrystals by Raman Spectroscopy, Powder X-ray Diffraction, Differential Scanning Calorimetry, and Transmission Raman Spectroscopy

2010 ◽  
Vol 10 (5) ◽  
pp. 2360-2371 ◽  
Author(s):  
M. A. Elbagerma ◽  
H. G. M. Edwards ◽  
T. Munshi ◽  
M. D. Hargreaves ◽  
Pavel Matousek ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Raman Spectroscopy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Raman

Thermodynamic and Structural Properties of Mev Ion Beam Amorphized Silicon

1989 ◽  
Vol 157 ◽  
Author(s):  
S. Roorda ◽  
W.C. Sinke ◽  
J.M. Poate ◽  
D.C. Jacobson ◽  
P. Fuoss ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Raman Spectroscopy ◽  
Structural Properties ◽  
Atomic Structure ◽  
Structural Relaxation ◽  
Ion Beam ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Amorphous Si

ABSTRACTThermodynamic and structural properties of amorphous Si (a-Si), prepared by MeV 28Si+-ion implantation are investigated by differential scanning calorimetry, Raman spectroscopy and X-ray diffraction. The influence of thermal annealing below 500 °C on a-Si is investigated with these different probes. The observed changes result from structural relaxation. Raman spectroscopy and X-ray diffraction show that structural relaxation is accompanied by changes in the average atomic structure.

scholarly journals Recent Advances in Solid-State Analysis of Pharmaceuticals

2015 ◽  
Vol 2 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Syed Nasir Abbas Bukhari ◽  
Ng Shin Hwei ◽  
Ibrahim Jantan
Keyword(s):  
Electron Microscopy ◽  
Nuclear Magnetic Resonance ◽  
Differential Scanning Calorimetry ◽  
Raman Spectroscopy ◽  
Solid State ◽  
Magnetic Resonance ◽  
Spatial Resolution ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray

Current analytical techniques for characterizing solid-state pharmaceuticals include powder x-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, infrared spectroscopy, Raman spectroscopy, electron microscopy and nuclear magnetic resonance. Powder x-ray diffraction and differential scanning calorimetry are mainstream techniques but they lack spatial resolution. Scanning electron microscopy and micro-Raman spectroscopy provide good chemical and optical characterization but they are not capable of analysing very small nanoparticles. Transmission electron microscopy and nano-thermal analysis can provide explicit characterization of nanoparticles but they are invasive. Nuclear magnetic resonance offers good spatial resolution but its use is mainly limited by poor sensitivity and high costs. In view of the many challenges posed by existing methods, new and novel techniques are being continually researched and developed to cater to the growing number of solid formulations in the pipeline and in the market. Some of the recent advances attained in the solid-state analysis of pharmaceutical are summarized in this review article.

Morphology of Polymer-Salt Complex Films Crossover from Fractal to Compact Aggregation

Fractals ◽  
1998 ◽  
Vol 06 (03) ◽  
pp. 285-292 ◽  
Author(s):  
Aninda Jiban Bhattacharyya ◽  
S. Banerjee ◽  
T. R. Middya ◽  
S. Tarafdar
Keyword(s):  
Differential Scanning Calorimetry ◽  
Polyethylene Oxide ◽  
Salt Concentration ◽  
Variable Temperature ◽  
Weight Fraction ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Polarizing Microscopy ◽  
X Ray ◽  
Salt Complex

In this paper we present a study of the variation of morphology of polyethylene oxide (PEO) films complexed with ammonium perchlorate ( NH 4 ClO 4) formed by evaporating a methanolic solution. Films with salt concentration x = 0 - 0.35 (x is the weight fraction of salt) were prepared for the morphology study. The wide varitey of structures obtained were systematically studied by photographs and polarizing microscopy. Some preliminary studies of x-ray diffraction, differential scanning calorimetry and variable temperature polarizing microscopy have also been done to identify the various phases present in the films.

The Rapid Simultaneous Measurement of Thermal and Structural Data by a Novel DSC/XRD Instrument

1984 ◽  
Vol 28 ◽  
pp. 227-232
Author(s):  
T. G. Fawcett ◽  
C. E. Crowder ◽  
L. F. Whiting ◽  
J. C. Tou ◽  
W. F. Scott ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
High Temperature ◽  
Solid State ◽  
Structural Data ◽  
State Transitions ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Precise Control ◽  
The Past

Over the past 25 years, numerous studies utilizing both X-ray diffraction (XRE) and differential scanning calorimetry (DSC) have been reported In the literature. Generally, conventional high-temperature X-ray data identifies solid-state transitions, then attempts to correlate them with thermal events observed by the calorimeter. Since changes occur in the sample during studies such as these, separate portions of the sample must be used for XRD and DSC experiments. When comparing results of the two experiments, questions arise concerning sample homogeniety as well as temperature and environmental differences. In fact, no conventional high-temperature X-ray diffraction instrument can give the precise control over temperature and heating rate available with a DSC, The problems of sample inhomogeneltles and Instrumental differences could be avoided if X-ray diffraction and DSC could be performed simultaneously on one sample.

Differential Scanning Calorimetry and Guinier Camera/High-Temperature X-Ray Diffraction Studies of the Oxygen Sublattice Phase Transition in the Yba2Cu3O7−x System

1987 ◽  
Vol 99 ◽  
Author(s):  
David S. Lee ◽  
Zezhong Fu ◽  
Egon Hellstern ◽  
William L. Johnson ◽  
Paul Pietrokowsky ◽  
...  
Keyword(s):  
Phase Transition ◽  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
High Temperature ◽  
Chemical Potential ◽  
X Ray Diffraction ◽  
Oxygen Sublattice ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Xrd Techniques

ABSTRACTWe have studied the phase transition of the oxygen sublattice in the YBa2Cu3O7−x system by Differential Scanning Calorimetry (DSC), Guinier Camera, and high temperature x-ray diffraction (ht-xrd) techniques. The transition was examined under different thermodynamic constraints (constant oxygen partial pressure and constant oxygen concentration) and for a range of oxygen partial pressures. The variation of the endothermic peak temperature with DSC scanning rate was used to deduce an activation energy for the transition. The average activation energy for the process is between 38.7–75.0 kcal/mole(l:2:3) [mole], depending on the thermodynamic constraint imposed on the system.Pressure versus concentration isotherms (P(C)) were used to determine the chemical potential of the oxygen in this system.

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