TY - JOUR

T1 - Dynamics and disorder

T2 - on the stability of pyrazinamide polymorphs

AU - Hoser, Anna Agnieszka

AU - Rekis, Toms

AU - Madsen, Anders Østergaard

N1 - Funding Information: The following funding is acknowledged: Lundbeckfonden (grant No. R324-2019-2018). AAH would like to acknowledge funding from Foundation for Polish Science, Homing/2016–1/3 grant, POIR.04.04.00-00-1DAE/16.

PY - 2022

Y1 - 2022

N2 - This article focuses on the structure and relative stability of four pyrazinamide polymorphs. New single crystal X-ray diffraction data collected for all forms at 10 14;K and 122 14;K are presented. By combining periodic ab initio DFT calculations with normal-mode refinement against X-ray diffraction data, both enthalpic and entropic contributions to the free energy of all polymorphs are calculated. On the basis of the estimated free energies, the stability order of the polymorphs as a function of temperature and the corresponding solid state phase transition temperatures are anticipated. It can be concluded that the α and γ forms have higher vibrational entropy than that of the β and δ forms and therefore they are significantly more stabilized at higher temperatures. Due to the entropy which arises from the disorder in γ form, it overcomes form α and is the most stable form at temperatures above ∼500 14;K. Our findings are in qualitative agreement with the experimental calorimetry results.

AB - This article focuses on the structure and relative stability of four pyrazinamide polymorphs. New single crystal X-ray diffraction data collected for all forms at 10 14;K and 122 14;K are presented. By combining periodic ab initio DFT calculations with normal-mode refinement against X-ray diffraction data, both enthalpic and entropic contributions to the free energy of all polymorphs are calculated. On the basis of the estimated free energies, the stability order of the polymorphs as a function of temperature and the corresponding solid state phase transition temperatures are anticipated. It can be concluded that the α and γ forms have higher vibrational entropy than that of the β and δ forms and therefore they are significantly more stabilized at higher temperatures. Due to the entropy which arises from the disorder in γ form, it overcomes form α and is the most stable form at temperatures above ∼500 14;K. Our findings are in qualitative agreement with the experimental calorimetry results.

KW - Enantiotropism

KW - Normal-mode refinement

KW - Periodic density functional theory

KW - Polymorphism

KW - Quantum crystallography

U2 - 10.1107/S2052520622004577

DO - 10.1107/S2052520622004577

M3 - Journal article

C2 - 35695115

AN - SCOPUS:85131852942

VL - 78

SP - 416

EP - 424

JO - Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials

JF - Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials

SN - 2052-5192

ER -