Suppression of isotopic polymorphism

Funnell, Nicholas P.; Allan, David R.; Maloney, A. F. J.; Smith, Ronald I.; Wilson, Cameron J. G.; Parsons, Simon

doi:10.1039/d0ce01636e

Cited by 4 publications

(7 citation statements)

References 48 publications

(57 reference statements)

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“…In other structures, for example, 3-fluorosalicylaldoxime (MIGPAU), similar features in the network volume (Figure (iv)) occur at the end of the pressure series before a destructive phase transition or loss of long-range order which prevented the collection of further diffraction data . A recent paper on the study of 4-methylpyridine pentachlorophenol (GADGUN) associated a similar feature with a destructive transition, which occurred on further increase in pressure . Detection of premonitory behavior will aid the interpretation of why transitions take place in some compounds but not in others and for rationalizing the limit of compression while maintaining long-range order.…”

Section: Resultsmentioning

confidence: 95%

“… 39 A recent paper on the study of 4-methylpyridine pentachlorophenol (GADGUN) associated a similar feature with a destructive transition, which occurred on further increase in pressure. 40 Detection of premonitory behavior will aid the interpretation of why transitions take place in some compounds but not in others and for rationalizing the limit of compression while maintaining long-range order.…”

Section: Resultsmentioning

confidence: 99%

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Behavior of Occupied and Void Space in Molecular Crystal Structures at High Pressure

Wilson

Cervenka

Wood

et al. 2022

Crystal Growth & Design

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We report a Monte Carlo algorithm for calculation of occupied (“network”) and unoccupied (“void”) space in crystal structures. The variation of the volumes of the voids and the network of intermolecular contacts with pressure sensitively reveals discontinuities associated with first- and second-order phase transitions, providing insights into the effect of compression (and, in principle, other external stimuli) at a level between those observed in individual contact distances and the overall unit cell dimensions. The method is shown to be especially useful for the correlation of high-pressure crystallographic and spectroscopic data, illustrated for naphthalene, where a phase transition previously detected by vibrational spectroscopy, and debated in the literature for over 80 years, has been revealed unambiguously in crystallographic data for the first time. Premonitory behavior before a phase transition and crystal collapse at the end of a compression series has also been detected. The network and void volumes for 129 high-pressure studies taken from the Cambridge Structural Database (CSD) were fitted to equation of state to show that networks typically have bulk moduli between 40 and 150 GPa, while those of voids fall into a much smaller range, 2–5 GPa. These figures are shown to reproduce the narrow range of overall bulk moduli of molecular solids ( ca. 5–20 GPa). The program, called CellVol, has been written in Python using the CSD Python API and can be run through the command line or through the Cambridge Crystallographic Data Centre’s Mercury interface.

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Behavior of Occupied and Void Space in Molecular Crystal Structures at High Pressure

Wilson

Cervenka

Wood

et al. 2022

Crystal Growth & Design

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“…The method has recently been used to identify structural behaviour in naphthalene, the Blatter radical and in 4-methylpyridine pentachlorophenol co-crystals. 32,46,47…”

Section: Resultsmentioning

confidence: 99%

“…The method has recently been used to identify structural behaviour in naphthalene, the Blatter radical and in 4methylpyridine pentachlorophenol co-crystals. 32,46,47 The network and void volumes in glyphosate are shown in Figure 5 as a function of pressure.…”

Section: Volume Analysismentioning

confidence: 99%

Discerning subtle high-pressure phase transitions in glyphosate

2023

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“…The total unit-cell volume can be broken down into contributions from interstitial void space and the network of intramolecular and intermolecular contacts using the method described by Novelli et al (2020) and Funnell et al (2021), where void space corresponds to the regions of the structure lying beyond the van der Waals radius of any of the atoms. Trends in the network and void volumes with pressure can reveal second-order effects which are not seen in the overall unit-cell volume.…”

Section: Volume Analysismentioning

confidence: 99%

A first-order phase transition in Blatter's radical at high pressure

Broadhurst¹,

Wilson²,

Zissimou³

et al. 2022

Acta Crystallogr Sect B

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The crystal structure of Blatter's radical (1,3-diphenyl-1,4-dihydrobenzo[e][1,2,4]triazin-4-yl) has been investigated between ambient pressure and 6.07 GPa. The sample remains in a compressed form of the ambient-pressure phase up to 5.34 GPa, the largest direction of strain being parallel to the direction of π-stacking interactions. The bulk modulus is 7.4 (6) GPa, with a pressure derivative equal to 9.33 (11). As pressure increases, the phenyl groups attached to the N1 and C3 positions of the triazinyl moieties of neighbouring pairs of molecules approach each other, causing the former to begin to rotate between 3.42 to 5.34 GPa. The onset of this phenyl rotation may be interpreted as a second-order phase transition which introduces a new mode for accommodating pressure. It is premonitory to a first-order isosymmetric phase transition which occurs on increasing pressure from 5.34 to 5.54 GPa. Although the phase transition is driven by volume minimization, rather than relief of unfavourable contacts, it is accompanied by a sharp jump in the orientation of the rotation angle of the phenyl group. DFT calculations suggest that the adoption of a more planar conformation by the triazinyl moiety at the phase transition can be attributed to relief of intramolecular H...H contacts at the transition. Although no dimerization of the radicals occurs, the π-stacking interactions are compressed by 0.341 (3) Å between ambient pressure and 6.07 GPa.

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Suppression of isotopic polymorphism

Abstract: Crystallisation at pressure overcomes the effect of isotopic polymorphism in the methylpyridine pentachlorophenol co-crystal. Though the hydrogenated Cc polymorph can only be obtained at pressure, it is stable on recovery to ambient conditions.

Cited by 4 publications

References 48 publications

Behavior of Occupied and Void Space in Molecular Crystal Structures at High Pressure

Behavior of Occupied and Void Space in Molecular Crystal Structures at High Pressure

Discerning subtle high-pressure phase transitions in glyphosate

A first-order phase transition in Blatter's radical at high pressure

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