Cardiff University | Prifysgol Caerdydd ORCA
Online Research @ Cardiff 
WelshClear Cookie - decide language by browser settings

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

Woodall, Christopher H., Christensen, Jeppe, Skelton, Jonathan M., Hatcher, Lauren E., Parlett, Andrew, Raithby, Paul R., Walsh, Aron, Parker, Stephen C., Beavers, Christine M., Teat, Simon J., Intissar, Mourad, Reber, Christian and Allan, David R. 2016. 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. IUCrJ 3 (5) , p. 376. 10.1107/S2052252516013129

[thumbnail of ed5009.pdf]
Preview
PDF - Published Version
Available under License Creative Commons Attribution.

Download (1MB) | Preview

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.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Chemistry
Publisher: International Union of Crystallography: Open Access / International Union of Crystallography
ISSN: 2052-2525
Date of First Compliant Deposit: 18 March 2020
Date of Acceptance: 15 August 2016
Last Modified: 19 Mar 2020 13:45
URI: https://orca.cardiff.ac.uk/id/eprint/130491

Citation Data

Cited 7 times in Scopus. View in Scopus. Powered By Scopus® Data

Actions (repository staff only)

Edit Item Edit Item

Downloads

Downloads per month over past year

View more statistics