Crystal packing and crystallization tendency from the melt of 2-((2-ethylphenyl)amino)nicotinic acid

2018 ◽  
Vol 233 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Arjun Kalra ◽  
Mingtao Zhang ◽  
Sean Parkin ◽  
Tonglei Li
Keyword(s):  
Nicotinic Acid ◽  
Crystal Packing ◽  
Amorphous State ◽  
Glass Forming Ability ◽  
Melt Quenching ◽  
Scanning Calorimetry ◽  
Glass Forming ◽  
Planar Conformation ◽  
Acid Acid ◽  
Crystallization Tendency

Abstract2-((2-ethylphenyl)amino)nicotinic acid (2EPNA) was synthesized and its crystal structure was determined. It was observed that alkylation of the phenyl ring with ethyl group disrupts the planar conformation of the molecule by steric repulsion, resulting in formation of an acid-pyridine heterosynthon (instead of acid-acid homosynthon) in the crystal. Crystallization tendency from the melt state of the polymorph was studied by differential scanning calorimetry (DSC). It was revealed that this compound could form a very stable amorphous phase on melt quenching and not crystallize even on re-heating. The formation of acid-pyridine hydrogen bonding in the amorphous state is believed to be responsible for its good glass forming ability.

scholarly journals Amorphous state stability of plant vitrification solutions

Biologija ◽  
2020 ◽  
Vol 66 (1) ◽  
Author(s):  
Krystyna Vozovyk ◽  
Olena Bobrova ◽  
Anton Prystalov ◽  
Nadiya Shevchenko ◽  
Larisa Kuleshova
Keyword(s):  
Glass Transition ◽  
Amorphous State ◽  
Glass Forming Ability ◽  
Ice Melting ◽  
Critical Factors ◽  
Scanning Calorimetry ◽  
Glass Transition Temperatures ◽  
Glass Forming ◽  
Warming Rate ◽  
The Stability

Two critical factors for obtaining high viable biological samples after cryopreservation by vitrification method are cryoprotectant glass-forming ability while cooling and the stability of its amorphous state during warming. The present work is devoted to the study of the amorphous state stability of plant vitrification solutions (PVS) by differential scanning calorimetry method. The objects of the study were PVS1 modified, PVS2, PVS3 modified, PVS4 and PVSN. The thermograms of PVSs, frozen in liquid nitrogen, were recorded at a warming rate of 0.5 deg/min. The glass transition temperatures of PVS1, PVS2 and PVS3 were –109.0°C, –115.3°C, and –93.9°C, respectively. Neither exo- nor endothermic peaks have been recorded, indicating no crystallization, at the cooling and the warming stages. PVS4 and PVSN thermograms, besides glass transition (–111.5°C and –110.0°C, correspondingly), showed crystallization from the amorphous state (devitrification) and ice melting peaks. Crystallization enthalpy of PVSN was 2.8 times higher compared to PVS4. This fact testifies that the crystalline phase was larger in PVSN compared to PVS4. It should be noted that crystallization in PVS4 and PVSN may be related to the low warming rate used during the experiment. At higher warming rates, this crystallization is likely to be avoided. Thus, PVS1, PVS2 and PVS3 have a high glass-forming ability and a stabile amorphous state. The amorphous state stability of PVS4 and PVSN is significantly lower compared to PVS1, PVS2, and PVS3.

Crystallochemistry of Amorphous State in Ni(Co, Fe)-Nb(V, Ta, Mo+Zr) Alloy Systems

2019 ◽  
Vol 31 ◽  
pp. 1-5
Author(s):  
Valeriy V. Savin ◽  
Ludmila A. Savina ◽  
Vera Semina ◽  
Vasiliy Semin ◽  
Natalia Pavlovna Dyakonova
Keyword(s):  
Amorphous State ◽  
Glass Forming Ability ◽  
Size Factor ◽  
Melt Quenching ◽  
Atomic Size ◽  
Glass Forming ◽  
Preparation Conditions ◽  
Rapid Melt Quenching ◽  
Quenching Method ◽  
Zr Alloy

Effects of the crystallochemical factors on amorphous state formation in the Ni−Nb-based systems are studied. Alloys with compositions (Ni, Co, Fe)−(Nb, Ta, V, Mo+Zr) are prepared by rapid melt quenching method with various cooling rates. It was found that at given preparation conditions and at certain atomic size factor, glass forming ability depends on factor of electron concentration was defined as number of s+d electrons per atom. Atomic size factor is necessary take into account, too. High glass forming ability of Ni−Nb alloys are attributed to formation possibility of two distinct E93 type phases.

scholarly journals Long-Term Physical (In)Stability of Spray-Dried Amorphous Drugs: Relationship with Glass-Forming Ability and Physicochemical Properties

Pharmaceutics ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 425 ◽  
Author(s):  
Edueng ◽  
Bergström ◽  
Gråsjö ◽  
Mahlin
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Physicochemical Properties ◽  
Physical Stability ◽  
Glass Forming Ability ◽  
Melt Quenching ◽  
Glass Forming ◽  
Spray Dried

This study shows the importance of the chosen method for assessing the glass-forming ability (GFA) and glass stability (GS) of a drug compound. Traditionally, GFA and GS are established using in situ melt-quenching in a differential scanning calorimeter. In this study, we included 26 structurally diverse glass-forming drugs (i) to compare the GFA class when the model drugs were produced by spray-drying with that when melt-quenching was used, (ii) to investigate the long-term physical stability of the resulting amorphous solids, and (iii) to investigate the relationship between physicochemical properties and the GFA of spray-dried solids and their long-term physical stability. The spray-dried solids were exposed to dry (<5% RH) and humid (75% RH) conditions for six months at 25 °C. The crystallization of the spray-dried solids under these conditions was monitored using a combination of solid-state characterization techniques including differential scanning calorimetry, Raman spectroscopy, and powder X-ray diffraction. The GFA/GS class assignment for 85% of the model compounds was method-dependent, with significant differences between spray-drying and melt-quenching methods. The long-term physical stability under dry condition of the compounds was predictable from GFA/GS classification and glass transition and crystallization temperatures. However, the stability upon storage at 75% RH could not be predicted from the same data. There was no strong correlation between the physicochemical properties explored and the GFA class or long-term physical stability. However, there was a slight tendency for compounds with a relatively larger molecular weight, higher glass transition temperature, higher crystallization temperature, higher melting point and higher reduced glass transition temperature to have better GFA and better physical stability. In contrast, a high heat of fusion and entropy of fusion seemed to have a negative impact on the GFA and physical stability of our dataset.

scholarly journals Myth or Truth: The Glass Forming Ability Class III Drugs Will Always Form Single-Phase Homogenous Amorphous Solid Dispersion Formulations

Pharmaceutics ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 529 ◽  
Author(s):  
Piyush Panini ◽  
Massimiliano Rampazzo ◽  
Abhishek Singh ◽  
Filip Vanhoutte ◽  
Guy Van den Mooter
Keyword(s):  
Single Phase ◽  
Solid Dispersions ◽  
Amorphous Solid ◽  
Glass Forming Ability ◽  
Amorphous Solid Dispersion ◽  
Class Iii ◽  
Scanning Calorimetry ◽  
Amorphous Solid Dispersions ◽  
Modulated Differential Scanning Calorimetry ◽  
Glass Forming

The physical stability of amorphous solid dispersions (ASD) of active pharmaceutical ingredients (APIs) of high glass forming ability (GFA class III) is generally expected to be high among the scientific community. In this study, the ASD of ten-selected class III APIs with the two polymers, PVPVA 64 and HPMC-E5, have been prepared by spray-drying, film-casting, and their amorphicity at T0 was investigated by modulated differential scanning calorimetry and powder X-ray diffraction. It was witnessed that only five out of ten APIs form good quality amorphous solid dispersions with no phase separation and zero crystalline content, immediately after the preparation and drying process. Hence, it was further established that the classification of an API as GFA class III does not guarantee the formulation of single phase amorphous solid dispersions.

Glass Forming Ability and Crystallization Kinetics of Al-Mg-Ni-La Metallic Glasses

2014 ◽  
Vol 960-961 ◽  
pp. 161-164 ◽  
Author(s):  
Juan Mu ◽  
Hai Feng Zhang
Keyword(s):  
Crystallization Kinetics ◽  
Glass Forming Ability ◽  
Continuous Heating ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Glass Forming ◽  
Dsc Measurements ◽  
Mg Addition ◽  
Kinetics Of ◽  
Thermal Stability Of

Glass forming ability and crystallization kinetics of Al-Mg-Ni-La alloys have been investigated by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The maximum thickness achievable in glasses of Al76Mg11Ni8La5and Al69Mg18Ni8La5ribbons were 200 and 120 μm, respectively. The crystallization temperature and peak temperature indicated by DSC measurements displayed dependence on the heating rate during continuous heating, and were coincident with Lanoka’s relationship. The activation energies for the crystallization reactionExwere obtained from the Kissinger’s equation. The results show the Mg addition is beneficial to the thermal stability of the amorphous phase.

Effect of Co Addition on the Glass-Forming Ability and Mechanical Properties of Ti-Zr-Be-Cu-Co Bulk Amorphous Alloys

2012 ◽  
Vol 182-183 ◽  
pp. 203-207
Author(s):  
Zhong Yuan Suo ◽  
Yan Ling Song ◽  
Ke Qiang Qiu
Keyword(s):  
Mechanical Properties ◽  
Glassy Alloy ◽  
Glass Forming Ability ◽  
Yield Strain ◽  
Scanning Calorimetry ◽  
High Fracture ◽  
Glass Forming ◽  
Transmission Electron ◽  
Bulk Glassy Alloy ◽  
Co Addition

The effect of Co substitution for Be on the glass-forming ability and mechanical properties was investigated in Ti35Zr30Be27.5-xCu7.5Cox (x=0, 3.5, 7.5, 11.5 at.%) alloys by using X-ray diffractometry (XRD), differential scanning calorimetry (DSC), high-resolution transmission electron microscopy (HRTEM) and compression test. With the substitution of Co for Be, glass-forming ability (GFA) is significantly enhanced and fully amorphous rods with a diameter of up to 12 mm were produced in the alloy with 3.5 and 7.5 at.% Co. The Ti35Zr30Be24Cu7.5Co3.5 bulk glassy alloy exhibits good plasticity of 4% during compressive applied load at ambient temperature in conjunction with distinct yield strain of 2% and high fracture strength of 2196 MPa. The effect of the addition of Co on the structure and deformation behavior of the Ti35Zr30Be27.5-xCu7.5Cox (x=0, 3.5, 7.5, 11.5 at.%) alloys is discussed.

Glass-Forming Ability and Crystallization Kinetics of Hf-Ti-Cu-Ni-Al Bulk Metallic Glass

2012 ◽  
Vol 479-481 ◽  
pp. 1786-1789 ◽  
Author(s):  
Tie Jun Chen
Keyword(s):  
Thermal Stability ◽  
Crystallization Kinetics ◽  
Glass Formation ◽  
Glass Forming Ability ◽  
Ideal Condition ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Cross Sectional ◽  
Glass Forming

Multi-component Hf45.6Cu27.8Ni9.3Ti5Al12.4bulk metallic glasses (BMGs) were prepared successfully by casted into the water-cooled Cu mold. Characterization of the casted Hf45.6Cu27.8Ni9.3Ti5Al12.4rods was carried out by X-ray diffraction. The thermal stability and crystallization kinetics were followed by differential scanning calorimetry. The results show that the alloy Hf45.6Cu27.8Ni9.3Ti5Al12.4had a critical cylindrical rod diameter for glass formation, Dc, of 7 mm and the largest cross-sectional diameter (about 12.4mm) can be obtained in the ideal condition. The critical cooling rate for glass formation is 6.48K/s. The Hf45.6Cu27.8Ni9.3Ti5Al12.4BMG has larger glass forming ability and higher thermal stability.

Effect of Zr addition on the glass-forming ability and mechanical properties of Ni–Nb alloy

2007 ◽  
Vol 22 (2) ◽  
pp. 453-459 ◽  
Author(s):  
Z.W. Zhu ◽  
H.F. Zhang ◽  
W.S. Sun ◽  
Z.Q. Hu
Keyword(s):  
Mechanical Properties ◽  
Glass Forming Ability ◽  
Compression Tests ◽  
Casting Method ◽  
Scanning Calorimetry ◽  
Glass Forming ◽  
Zr Addition ◽  
Pattern Structures ◽  
Injection Casting ◽  
Zr Alloys

The effect of zirconium (Zr) addition on the glass-forming ability (GFA) and mechanical properties of the Ni61.5Nb38.5 alloy has been studied. The addition of Zr improves the GFA. When x = 5 for Ni61.5Nb38.5−xZrx (in at.%) alloys, the alloy exhibits the best GFA and can be cast into 3-mm-diameter amorphous samples by using the copper mold injection-casting method. Differential scanning calorimetry measurements indicated that the thermal parameters, such as Trg and γ, have not a good correlation with the GFA in the Ni–Nb–Zr alloys. Compression tests reveal that the addition of Zr just decreases the fracture strength slightly from 3.4 to 3 GPa and that all of the tested samples exhibit a little compressive plasticity of about 2%. When x = 9, the feature of the fracture surface indicates that the alloy has a tendency for transition from the ductile to the brittle. And delicate “dimple” and microscale vein pattern structures have been observed on it.

Thermodynamics of Te80Ge20 − x Pbx glass-forming alloys

1988 ◽  
Vol 3 (3) ◽  
pp. 570-575 ◽  
Author(s):  
L. Battezzati ◽  
A. L. Greer
Keyword(s):  
Free Energy ◽  
Specific Heat ◽  
Glass Forming Ability ◽  
Undercooled Liquid ◽  
Scanning Calorimetry ◽  
Entropy Of Fusion ◽  
Glass Forming ◽  
Crystal Phases ◽  
Solid Phases ◽  
Liquid And Solid Phases

The specific heat of liquid and solid phases and the heats of crystallization and fusion have been measured by differential scanning calorimetry (DSC) for a series of Te80Ge20 − x Pbx alloys (0≤x≤20). The enthalpy, entropy, and free energy of the undercooled liquid are quantitatively assessed with reference to the crystal phases. The available formulas for computing the free energy of the liquid are compared, and their relative merits are discussed. The glass transition temperature is shown to depend strongly on the ratio of the average excess specific heat of the liquid to the entropy of fusion. An anomaly in the liquid specific heat, which is particularly important for Te80Ge20 and Te80Ge15Pb5, leads to very good glass forming ability for these alloys; this is demonstrated by preparing amorphous samples by means of fluxing.

GLASS FORMING ABILITY AND KINETIC CHARACTERS OF PARAMAGNETIC Nd60Co40-xAlx(x=5, 10, 15) BULK METALLIC GLASSES

2004 ◽  
Vol 18 (14) ◽  
pp. 679-685 ◽  
Author(s):  
L. XIA ◽  
Y. D. DONG
Keyword(s):  
Glass Transition ◽  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
Supercooled Liquid ◽  
Supercooled Liquid Region ◽  
Glass Forming Ability ◽  
Ternary Alloys ◽  
Liquid Region ◽  
Scanning Calorimetry ◽  
Glass Forming

Paramagnetic Nd 60 Co 40-x Al x(x=5, 10, 15) bulk metallic glasses (BMGs) were prepared in the shape of rods 2 mm in diameter by suction casting. The ternary alloys have shown distinct glass transitions in Differential Scanning Calorimetry (DSC) measurements and excellent glass-forming ability. The glass transition and crystallization behaviors as well as their kinetics have been studied. The reduced glass transition temperature and the supercooled liquid region of the alloys were found to increase with the increasing content of Al . The role of Al was discussed. The parameter γ defined by Liu et al. was employed to discuss the glass-forming ability of the alloys and the critical cooling rates as well as the critical section thickness of the alloys were predicted accordingly.

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