Observation of a re-entrant phase transition in the molecular complex tris­(μ2-3,5-diiso­propyl-1,2,4-triazolato-κ2N1:N2)trigold(I) under high pressure

Paul Raithby, Christopher Woodall, Jeppe Christensen, Jonathan Skelton, Lauren Hatcher, Andrew Parlett, Aron Walsh, Stephen Parker, Christine M. Beavers, Simon Teat, Mourad Intissar, Christian Reber, David R. Allan

Research output: Contribution to journalArticle

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Abstract

We report a molecular crystal that exhibits four successive phase transitions under hydro­static pressure, driven by aurophilic interactions, with the ground-state structure re-emerging at high pressure. The effect of pressure on two polytypes of tris(μ2-3,5-diiso­propyl-1,2,4-triazolato-κ2N1:N2)trigold(I) (denoted Form-I and Form-II) has been analysed using luminescence spectroscopy, single-crystal X-ray diffraction and first-principles computation. A unique phase behaviour was observed in Form-I, with a complex sequence of phase transitions between 1 and 3.5 GPa. The ambient C2/c mother cell transforms to a P21/n phase above 1 GPa, followed by a P21/a phase above 2 GPa and a large-volume C2/c supercell at 2.70 GPa, with the previously observed P21/n phase then reappearing at higher pressure. The observation of crystallographically identical low- and high-pressure P21/n phases makes this a rare example of a re-entrant phase transformation. The phase behaviour has been characterized using detailed crystallographic theory and modelling, and rationalized in terms of molecular structural distortions. The dramatic changes in conformation are correlated with shifts of the luminescence maxima, from a band maximum at 14040 cm−1 at 2.40 GPa, decreasing steeply to 13550 cm−1 at 3 GPa. A similar study of Form-II displays more conventional crystallographic behaviour, indicating that the complex behaviour observed in Form-I is likely to be a direct consequence of the differences in crystal packing between the two polytypes.
LanguageEnglish
Pages367
Number of pages376
JournalIUCrJ
Volume3
Issue number5
DOIs
StatusPublished - 1 Sep 2016

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Phase Transition
Phase transitions
Observation
Pressure
Phase behavior
luminescence
Luminescence
static pressure
crystals
phase transformations
Molecular crystals
emerging
low pressure
X-Ray Diffraction
Ground state
ground state
Conformations
shift
Spectrum Analysis
single crystals

Keywords

  • re-entrant phase transitions; high-pressure crystallography; gold(I); luminescence spectroscopy; DFT calculations

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Observation of a re-entrant phase transition in the molecular complex tris­(μ2-3,5-diiso­propyl-1,2,4-triazolato-κ2N1:N2)trigold(I) under high pressure. / Raithby, Paul; Woodall, Christopher; Christensen, Jeppe; Skelton, Jonathan; Hatcher, Lauren; Parlett, Andrew; Walsh, Aron; Parker, Stephen; Beavers, Christine M.; Teat, Simon; Intissar, Mourad; Reber, Christian; Allan, David R.

In: IUCrJ, Vol. 3, No. 5, 01.09.2016, p. 367.

Research output: Contribution to journalArticle

Raithby, Paul ; Woodall, Christopher ; Christensen, Jeppe ; Skelton, Jonathan ; Hatcher, Lauren ; Parlett, Andrew ; Walsh, Aron ; Parker, Stephen ; Beavers, Christine M. ; Teat, Simon ; Intissar, Mourad ; Reber, Christian ; Allan, David R. / Observation of a re-entrant phase transition in the molecular complex tris­(μ2-3,5-diiso­propyl-1,2,4-triazolato-κ2N1:N2)trigold(I) under high pressure. In: IUCrJ. 2016 ; Vol. 3, No. 5. pp. 367.
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abstract = "We report a molecular crystal that exhibits four successive phase transitions under hydro­static pressure, driven by aurophilic interactions, with the ground-state structure re-emerging at high pressure. The effect of pressure on two polytypes of tris(μ2-3,5-diiso­propyl-1,2,4-triazolato-κ2N1:N2)trigold(I) (denoted Form-I and Form-II) has been analysed using luminescence spectroscopy, single-crystal X-ray diffraction and first-principles computation. A unique phase behaviour was observed in Form-I, with a complex sequence of phase transitions between 1 and 3.5 GPa. The ambient C2/c mother cell transforms to a P21/n phase above 1 GPa, followed by a P21/a phase above 2 GPa and a large-volume C2/c supercell at 2.70 GPa, with the previously observed P21/n phase then reappearing at higher pressure. The observation of crystallographically identical low- and high-pressure P21/n phases makes this a rare example of a re-entrant phase transformation. The phase behaviour has been characterized using detailed crystallographic theory and modelling, and rationalized in terms of molecular structural distortions. The dramatic changes in conformation are correlated with shifts of the luminescence maxima, from a band maximum at 14040 cm−1 at 2.40 GPa, decreasing steeply to 13550 cm−1 at 3 GPa. A similar study of Form-II displays more conventional crystallographic behaviour, indicating that the complex behaviour observed in Form-I is likely to be a direct consequence of the differences in crystal packing between the two polytypes.",
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T1 - Observation of a re-entrant phase transition in the molecular complex tris­(μ2-3,5-diiso­propyl-1,2,4-triazolato-κ2N1:N2)trigold(I) under high pressure

AU - Raithby, Paul

AU - Woodall, Christopher

AU - Christensen, Jeppe

AU - Skelton, Jonathan

AU - Hatcher, Lauren

AU - Parlett, Andrew

AU - Walsh, Aron

AU - Parker, Stephen

AU - Beavers, Christine M.

AU - Teat, Simon

AU - Intissar, Mourad

AU - Reber, Christian

AU - Allan, David R.

PY - 2016/9/1

Y1 - 2016/9/1

N2 - We report a molecular crystal that exhibits four successive phase transitions under hydro­static pressure, driven by aurophilic interactions, with the ground-state structure re-emerging at high pressure. The effect of pressure on two polytypes of tris(μ2-3,5-diiso­propyl-1,2,4-triazolato-κ2N1:N2)trigold(I) (denoted Form-I and Form-II) has been analysed using luminescence spectroscopy, single-crystal X-ray diffraction and first-principles computation. A unique phase behaviour was observed in Form-I, with a complex sequence of phase transitions between 1 and 3.5 GPa. The ambient C2/c mother cell transforms to a P21/n phase above 1 GPa, followed by a P21/a phase above 2 GPa and a large-volume C2/c supercell at 2.70 GPa, with the previously observed P21/n phase then reappearing at higher pressure. The observation of crystallographically identical low- and high-pressure P21/n phases makes this a rare example of a re-entrant phase transformation. The phase behaviour has been characterized using detailed crystallographic theory and modelling, and rationalized in terms of molecular structural distortions. The dramatic changes in conformation are correlated with shifts of the luminescence maxima, from a band maximum at 14040 cm−1 at 2.40 GPa, decreasing steeply to 13550 cm−1 at 3 GPa. A similar study of Form-II displays more conventional crystallographic behaviour, indicating that the complex behaviour observed in Form-I is likely to be a direct consequence of the differences in crystal packing between the two polytypes.

AB - We report a molecular crystal that exhibits four successive phase transitions under hydro­static pressure, driven by aurophilic interactions, with the ground-state structure re-emerging at high pressure. The effect of pressure on two polytypes of tris(μ2-3,5-diiso­propyl-1,2,4-triazolato-κ2N1:N2)trigold(I) (denoted Form-I and Form-II) has been analysed using luminescence spectroscopy, single-crystal X-ray diffraction and first-principles computation. A unique phase behaviour was observed in Form-I, with a complex sequence of phase transitions between 1 and 3.5 GPa. The ambient C2/c mother cell transforms to a P21/n phase above 1 GPa, followed by a P21/a phase above 2 GPa and a large-volume C2/c supercell at 2.70 GPa, with the previously observed P21/n phase then reappearing at higher pressure. The observation of crystallographically identical low- and high-pressure P21/n phases makes this a rare example of a re-entrant phase transformation. The phase behaviour has been characterized using detailed crystallographic theory and modelling, and rationalized in terms of molecular structural distortions. The dramatic changes in conformation are correlated with shifts of the luminescence maxima, from a band maximum at 14040 cm−1 at 2.40 GPa, decreasing steeply to 13550 cm−1 at 3 GPa. A similar study of Form-II displays more conventional crystallographic behaviour, indicating that the complex behaviour observed in Form-I is likely to be a direct consequence of the differences in crystal packing between the two polytypes.

KW - re-entrant phase transitions; high-pressure crystallography; gold(I); luminescence spectroscopy; DFT calculations

UR - http://dx.doi.org/10.1107/S2052252516013129

UR - http://dx.doi.org/10.1107/S2052252516013129

U2 - 10.1107/S2052252516013129

DO - 10.1107/S2052252516013129

M3 - Article

VL - 3

SP - 367

JO - IUCrJ

T2 - IUCrJ

JF - IUCrJ

SN - 2052-2525

IS - 5

ER -