TY - JOUR

T1 - Low temperature and high-pressure study of bending L-leucinium hydrogen maleate crystals

AU - Skakunova, Kseniya D.

AU - Rychkov, Denis A.

N1 - Funding Information: Funding: Computational part of this research was funded by the Russian Science Foundation, grant number 21-73-00094. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

PY - 2021/12

Y1 - 2021/12

N2 - The polymorphism of molecular crystals is a well-known phenomenon, resulting in modifications of physicochemical properties of solid phases. Low temperatures and high pressures are widely used to find phase transitions and quench new solid forms. In this study, L-Leucinium hydrogen maleate (LLHM), the first molecular crystal that preserves its anomalous plasticity at cryogenic temperatures, is studied at extreme conditions using Raman spectroscopy and optical microscopy. LLHM was cooled down to 11 K without any phase transition, while high pressure impact leads to perceptible changes in crystal structure in the interval of 0.0–1.35 GPa using pentane-isopentane media. Surprisingly, pressure transmitting media (PTM) play a significant role in the behavior of the LLHM system at extreme conditions—we did not find any phase change up to 3.05 GPa using paraffin as PTM. A phase transition of LLHM to amorphous form or solid–solid phase transition(s) that results in crystal fracture is reported at high pressures. LLHM stability at low temperatures suggests an alluring idea to prove LLHM preserves plasticity below 77 K.

AB - The polymorphism of molecular crystals is a well-known phenomenon, resulting in modifications of physicochemical properties of solid phases. Low temperatures and high pressures are widely used to find phase transitions and quench new solid forms. In this study, L-Leucinium hydrogen maleate (LLHM), the first molecular crystal that preserves its anomalous plasticity at cryogenic temperatures, is studied at extreme conditions using Raman spectroscopy and optical microscopy. LLHM was cooled down to 11 K without any phase transition, while high pressure impact leads to perceptible changes in crystal structure in the interval of 0.0–1.35 GPa using pentane-isopentane media. Surprisingly, pressure transmitting media (PTM) play a significant role in the behavior of the LLHM system at extreme conditions—we did not find any phase change up to 3.05 GPa using paraffin as PTM. A phase transition of LLHM to amorphous form or solid–solid phase transition(s) that results in crystal fracture is reported at high pressures. LLHM stability at low temperatures suggests an alluring idea to prove LLHM preserves plasticity below 77 K.

KW - Bending crystal

KW - High-pressure

KW - L-Leucinium hydrogen maleate

KW - Low temperature

KW - Plastic crystals

KW - Plasticity

KW - Raman spectroscopy

UR - http://www.scopus.com/inward/record.url?scp=85121652252&partnerID=8YFLogxK

U2 - 10.3390/cryst11121575

DO - 10.3390/cryst11121575

M3 - Article

AN - SCOPUS:85121652252

VL - 11

JO - Crystals

JF - Crystals

SN - 2073-4352

IS - 12

M1 - 1575

ER -