Stabilization of Metastable Flufenamic Acid by Inclusion of Mefenamic Acid: Solid Solution or Epilayer?

Lee, Eun Hee; Byrn, Stephen R.

doi:10.1002/jps.22250

Cited by 24 publications

(19 citation statements)

References 24 publications

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“…TFA and MFA have crystalline conformations in both wells, and there is only a small energy barrier between all observed conformations in isolation. The differences in low energy conformations may explain why MFA can be incorporated as an impurity into FFA I , more readily than FFA III and that the MFA impurity inhibits the polymorphic transition from FFA I to III. In the case of FFA growth on other templates, the large barrier for FFA III molecules to change conformation to the shape adopted by MFA and TFA polymorphs may also provide a kinetic barrier to forming new FFA polymorphs.…”

Section: Discussionmentioning

confidence: 99%

Successful Computationally Directed Templating of Metastable Pharmaceutical Polymorphs

Case

Srirambhatla

Guo

et al. 2018

Crystal Growth & Design

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A strategy of using crystal structure prediction (CSP) methods to determine which, if any, isostructural template could facilitate the first crystallization of a predicted polymorph by vapor deposition is extended to the fenamate family. Mefenamic acid (MFA) and tolfenamic acid (TFA) are used as molecules with minimal chemical differences, whereas flufenamic acid (FFA) shows greater differences in the substituents. The three crystal energy landscapes were calculated, and periodic electronic structure calculations were used to confirm the thermodynamic plausibility of possible isostructural polymorphs to experimentally obtainable crystals of the other molecules. As predicted, a new polymorph, TFA form VI, was found by sublimation onto isomorphous MFA form I, using a recently developed technique. MFA and TFA form a continuous solid solution with the structure of MFA I and TFA VI at the limits, but the isomorphous MFA/FFA solid solution does not extended to a new polymorph of FFA. The novel solid solution structure of TFA and FFA was found, and a new isomorphous polymorph TFA VII was found by sublimation onto this new solid solution template. Sublimation of TFA onto a metal surface at the early stage of deposition gave TFA form VIII. We rationalize the formation of new polymorphs of only TFA.

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Section: Discussionmentioning

confidence: 99%

Successful Computationally Directed Templating of Metastable Pharmaceutical Polymorphs

Case

Srirambhatla

Guo

et al. 2018

Crystal Growth & Design

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“…25 Commercially distributed FFA is a mixture of the two room-temperature accessible polymorphs, forms I and III, where form III is the thermodynamically stable polymorph at room temperature, with form I emerging enantiotropically above 42°C. 26 Computational techniques such as the Bravais-Friedel-Donnay-Harker (BFDH) method can be used to predict the morphologies of the expected polymorphs of FFA to infer the resultant polymorph of crystals in situ. Understanding and controlling the spontaneity of polymorphism, in order to achieve selectivity of a more soluble polymorph or even uncover a more stable polymorph, are aims that remain at the forefront of pharmaceutical research.…”

Section: Introductionmentioning

confidence: 99%

Visualising early-stage liquid phase organic crystal growthvialiquid cell electron microscopy

et al. 2020

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“…This is not caused by a too fast cooling rate as this behaviour was observed at different scan rates (Figure S5). Instead, we suspect that SA : MBC 2 : 1 might be a metastable crystal that crystallizes only in the presence of certain solvents .

T_{0}

has been reported to be approximately 40 °C below the glass transition temperature ( T g ), here

T_{0}

(Table ) is 35 °C lower than the T g (Figure d).…”

Section: Resultsmentioning

confidence: 82%

A Silatrane:Molecule‐Based Crystal Composite Solid‐State Electrolyte for All‐Solid‐State Lithium Batteries

Navarro‐Suárez

Johansson

2019

Batteries & Supercaps

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All-solid-state batteries (ASSBs) are promoted as a promising option towards higher energies and power densities as well as drastically reduced safety risks as compared to conventional lithium-ion batteries (LIBs). Herein, a composite solid-state electrolyte (SSE) based on two crystalline materials with two distinctly different ion conduction mechanisms, percolation and ion hopping, is reported. By combining a silatrane (SA; here ethoxysilatrane) with a molecule-based crystal (MBC; here LiTFSI-TMEDA) the resulting SA : MBC 2 : 1 crystalline composite shows an appreciable ion conductivity of 10 À 5 S cm À 1 at room temperature, and low apparent activation energy, 836 K, for the ion transport. Studies of the overall and local structure show that in the composite the Li + and TFSI ions are dissociated, and this seems to be mediated by the SA part of the matrix. As a proof-of-concept, an ASSB based on this SSE can operate at 50°C providing up to 105 mAh g À 1 during 20 cycles.[a] Dr.

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Stabilization of Metastable Flufenamic Acid by Inclusion of Mefenamic Acid: Solid Solution or Epilayer?

Cited by 24 publications

References 24 publications

Successful Computationally Directed Templating of Metastable Pharmaceutical Polymorphs

Successful Computationally Directed Templating of Metastable Pharmaceutical Polymorphs

Visualising early-stage liquid phase organic crystal growthvialiquid cell electron microscopy

A Silatrane:Molecule‐Based Crystal Composite Solid‐State Electrolyte for All‐Solid‐State Lithium Batteries

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