title: Exploration of the pyrazinamide polymorphism at high pressure.
abstract: We report the high-pressure response of three forms (α, δ, and γ) of pyrazinamide (C(5)H(5)N(3)O, PZA) by in situ Raman spectroscopy and synchrotron X-ray diffraction techniques with a pressure of about 14 GPa. These different forms are characterized by various intermolecular bonding schemes. High-pressure experimental results show that the γ phase undergoes phase transition to the β phase at a pressure of about 4 GPa, whereas the other two forms retain their original structures at a high pressure. We propose that the stabilities of the α and δ forms upon compression are due to the special dimer connection that these forms possess. On the other hand, the γ form, which does not have this connection, prefers to transform to the closely related β form when pressure is applied. The detailed mechanism of the phase transition together with the stability of the three polymorphs is discussed by taking molecular stacking into account.
authors.affiliation: State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Tan
authors.forename: Kai
authors.initials: K
authors.lastname: Wang
authors.forename: Shourui
authors.initials: S
authors.lastname: Li
authors.forename: Hongsheng
authors.initials: H
authors.lastname: Yuan
authors.forename: Tingting
authors.initials: T
authors.lastname: Yan
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.forename: Ke
authors.initials: K
authors.lastname: Yang
authors.forename: Bingbing
authors.initials: B
authors.lastname: Liu
authors.forename: Guangtian
authors.initials: G
authors.lastname: Zou
authors.forename: Bo
authors.initials: B
authors.lastname: Zou
mesh_terms: D008958:Models, Molecular; D011312:Pressure; D011718:Pyrazinamide / Q000138:chemical synthesis* / Q000737:chemistry; D013059:Spectrum Analysis, Raman; D017356:Synchrotrons; D014961:X-Ray Diffraction
chemical_list: D011718:Pyrazinamide