Some physicochemical studies on organic eutectics and 1:1 addition compound; p-phenylenediamine – benzoic acid system

1989 ◽  
Vol 67 (2) ◽  
pp. 239-244 ◽  
Author(s):  
U. S. Rai ◽  
K. D. Mandal
Keyword(s):  
Phase Diagram ◽  
Benzoic Acid ◽  
Cluster Formation ◽  
Growth Front ◽  
Spectral Studies ◽  
Acid System ◽  
Addition Compound ◽  
X Ray Diffraction ◽  
X Ray ◽  
Entropy Of Fusion

The phase diagram of p-phenylenediamine – benzoic acid system, determined by the thaw–melt method, shows the formation of two eutectics and a 1:1 addition compound. The linear velocity of crystallization of pure components, eutectics and addition compound, determined by measuring the movement of growth front in a capillary, suggests that crystallization data obey the Hillig–Turnbull equation. Using experimental values of heats of fusion, entropy of fusion and excess thermodynamic functions were calculated and the results are explained on the basis of cluster formation in the melts. X-ray diffraction data infer that these eutectics are not simply the mechanical mixture of the two components and there is preferential ordering of atomic planes during their formation. The infrared spectral studies suggest the formation of intermolecular hydrogen bonding between the components forming the molecular complex. Keywords: organic eutectics, growth kinetics, phase diagram, thermochemistry, X-ray diffraction studies.

A physicochemical study on organic eutectics and addition compound; benzidine–pyrogallol system

1992 ◽  
Vol 70 (12) ◽  
pp. 2869-2874 ◽  
Author(s):  
U. S. Rai ◽  
Santhi George
Keyword(s):  
Phase Diagrams ◽  
Growth Front ◽  
Physicochemical Study ◽  
Addition Compound ◽  
X Ray Diffraction ◽  
Organic System ◽  
X Ray ◽  
Solidification Behaviour ◽  
Mechanical Mixtures ◽  
Microscopic Investigations

The phase diagrams of the binary organic system of benzidine–pyrogallol was determined by the thaw–melt method. The solidification behaviour of the pure components, their eutectics, and the addition compound were studied by measuring the movement of growth front in a capillary. From the data on X-ray diffraction, thermal and microscopic investigations it can be inferred that the eutectics are not simple mechanical mixtures of the components involved. The IR and NMR spectral investigations were carried out to throw light on the nature of bonding between the two components forming the addition compound.

X-ray-diffraction study of the superliquid region of the phase diagram of a Langmuir monolayer

1992 ◽  
Vol 45 (8) ◽  
pp. 5734-5737 ◽  
Author(s):  
M. C. Shih ◽  
T. M. Bohanon ◽  
J. M. Mikrut ◽  
P. Zschack ◽  
P. Dutta
Keyword(s):  
Phase Diagram ◽  
Diffraction Study ◽  
Langmuir Monolayer ◽  
X Ray Diffraction ◽  
X Ray

A combined ESR/X-ray diffraction study of the Y2O3–BaO–CuO phase diagram

1990 ◽  
Vol 86 (4) ◽  
pp. 675-682 ◽  
Author(s):  
Ruth Jones ◽  
Robert Janes ◽  
Robert Armstrong ◽  
Nicholas C. Pyper ◽  
Peter P. Edwards ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Diffraction Study ◽  
X Ray Diffraction ◽  
X Ray

Microstructure of Zr-25at. %Al Melt Spun Ribbons.

1994 ◽  
Vol 364 ◽  
Author(s):  
L. Lutterotti ◽  
S. K. Pradhan ◽  
S. Gialanella ◽  
A. R. Yavari
Keyword(s):  
Phase Diagram ◽  
Intermetallic Phases ◽  
X Ray Diffraction ◽  
Major Phase ◽  
X Ray ◽  
Metastable Structures ◽  
Melt Spun ◽  
Crystallographic Structures ◽  
Melt Spun Ribbons

AbstractFollowing a previous study in which we presented some microstructural aspects of meltspun ribbons having a composition close to Zr-25 at.% Al, we discuss now the crystallography of the phases observed in similar samples. We performed X-Ray diffraction analyses of ribbons and refined the observed crystallographic structures. We could identify a number of stable and metastable structures, according to the actual composition of the ribbons. We also estimated the percentage of each one of these phases. We did the same for some ribbons annealed at 750°C for several times. In this way we could follow the kinetics leading from the initial as-spun condition to the final one, featuring the L12 ordered Zr3Al, as the major phase, and other intermetallic phases of the Zr-Al phase diagram.

scholarly journals Engineering cocrystals of Paliperidone with enhanced solubility and dissolution characteristics

2021 ◽  
Vol 71 (5) ◽  
pp. 393-409
Author(s):  
Earle Radha-Rani ◽  
Gadela Venkata-Radha
Keyword(s):  
Benzoic Acid ◽  
Aqueous Solubility ◽  
Water Soluble ◽  
X Ray Diffraction ◽  
X Ray ◽  
Water Soluble Drug ◽  
Novel Approach ◽  
Enhanced Solubility ◽  
Poorly Water Soluble ◽  
Poorly Water Soluble Drug

In the present study, co-crystals (CCs) of Paliperidone (PPD) with coformers like benzoic acid (BA) and P-amino benzoic acid (PABA) were synthesized and characterized to improve the physicochemical properties and dissolution rate. CCs were prepared by the solvent evaporation (SE) technique and were compared with the products formed by neat grinding (NG) and liquid assisted grinding (LAG) in their enhancement of solubility. The formation of CCs was confirmed by the IR spectroscopy, powder X-ray diffraction and thermal analysis methods. The saturation solubility studies indicate that the aqueous solubility of PPD-BA and PPD-PABA CCs was significantly improved to 1.343±0.162mg/ml and 1.964±0.452mg/ml, respectively, in comparison with the PPD solubility of 0.473mg/ml. This increase in solubility is 2.83-and 3.09-fold, respectively. PPD exhibited a poor dissolution of 37.8% in 60min, while the dissolution of the CCs improved tremendously to 96.07% and 89.65% in 60min. CCs of PPD with BA and PABA present a novel approach to overcome the solubility challenges of poorly water-soluble drug PPD.

scholarly journals Influence of the Para-Substituent in Lanthanoid Complexes of Bistetrazole Substituted Calix[4]arenes

2019 ◽  
Author(s):  
Rene Z.H. Phe ◽  
Brian Skelton ◽  
Massimiliano Massi ◽  
Mark Ogden
Keyword(s):  
Structural Changes ◽  
Cluster Formation ◽  
Ammonium Cation ◽  
Ammonium Salts ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Mononuclear Complexes ◽  
Scattering Measurements ◽  
The Impact

5,11,17,23-Tetra-tert-butyl-25,27-dihydroxy-26,28-bis(tetrazole-5-ylmethoxy)calix[4]arene has been reported to form remarkable Ln19 and Ln12 elongated clusters, upon addition of aqueous ammonium carboxylates. The impact of the <i>para</i> substituent on lanthanoid cluster formation has been studied by synthesising two new bis-tetrazole calixarenes, with <i>p</i>-H, and <i>p</i>-allyl substituents. Solution phase dynamic light scattering measurements of the reaction mixtures indicated that clusters are not formed with the <i>p</i>-H and <i>p</i>-allyl derivatives, in contrast with the behaviour of the <i>t-</i>butyl analogue. Lanthanoid complexes of the <i>p</i>-H and <i>p</i>-allyl calixarenes were characterised by single crystal X-ray diffraction, and were found to form mononuclear complexes, linked to form a one-dimensional coordination polymer for the <i>p</i>-allyl system. All of the complexes were isolated as ammonium salts, with ammonium cation included in the calixarene cavity in most cases. It is concluded that the nature of the <i>para</i> substituent has a profound impact on the lanthanoid cluster formation process, and derivatives with more subtle structural changes will be required to determine if additional lanthanoid “bottlebrush” clusters can be isolated.<br><br>

The Zirconium-Iron System

1962 ◽  
Vol 6 ◽  
pp. 62-73 ◽  
Author(s):  
F. N. Rhines ◽  
R. W. Gould
Keyword(s):  
Phase Diagram ◽  
Microprobe Analysis ◽  
X Ray Diffraction ◽  
Metallographic Study ◽  
X Ray

AbstractBy means of a combined X-ray diffraction and metallographic study, two heretofore unrecognized phases, Zr4Fe and Zr2Fe, have been identified. Approximate verification of this finding has been made by Dr. David Levinson, using microprobe analysis. A tentative revision of the Zr-Fe phase diagram is proposed.

scholarly journals Advances in the Use of Microfluidics to Study Crystallization Fundamentals

2019 ◽  
Vol 10 (1) ◽  
pp. 59-83 ◽  
Author(s):  
Nadine Candoni ◽  
Romain Grossier ◽  
Mehdi Lagaize ◽  
Stéphane Veesler
Keyword(s):  
Phase Diagram ◽  
Diffraction Analysis ◽  
High Throughput ◽  
Concentration Measurement ◽  
Ultraviolet Spectroscopy ◽  
X Ray Diffraction ◽  
Chemical Library ◽  
Microfluidic Platform ◽  
X Ray ◽  
Phase Diagram Determination

This review compares droplet-based microfluidic systems used to study crystallization fundamentals in chemistry and biology. An original high-throughput droplet-based microfluidic platform is presented. It uses nanoliter droplets, generates a chemical library, and directly solubilizes powder, thus economizing both material and time. It is compatible with all solvents without the need for surfactant. Its flexibility permits phase diagram determination and crystallization studies (screening and optimizing experiments) and makes it easy to use for nonspecialists in microfluidics. Moreover, it allows concentration measurement via ultraviolet spectroscopy and solid characterization via X-ray diffraction analysis.

scholarly journals The phase diagram of a mixed halide (Br, I) hybrid perovskite obtained by synchrotron X-ray diffraction

RSC Advances ◽  
2019 ◽  
Vol 9 (20) ◽  
pp. 11151-11159 ◽  
Author(s):  
Frederike Lehmann ◽  
Alexandra Franz ◽  
Daniel M. Többens ◽  
Sergej Levcenco ◽  
Thomas Unold ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Solid Solution ◽  
Phase Separation ◽  
Structural Changes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hybrid Perovskite

The phase diagram elucidates structural changes and phase separation effects, induced by halide substitution in hybrid perovskite MAPb(I,Br)3 solid solution.

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