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.

The phase relationship between the pyrazinamide polymorphs α and γ

“…RT d 275.136 0.67294 PYRZIN05 (Nakata and Takaki, 1987) Pc 293 275.917 0.67485 PYRZIN17 (Castro et al, 2009) Pc (with disorder) e 100 268.057 0.65562 PYRZIN19 (Cherukuvada et al, 2010) Pc (without disorder) f 100 267.226 0.65359 PYRZIN20 (Cherukuvada et al, 2010) a The data is obtained from the CSD. Including pressure into the analysis, Tan et al found crystallographic indications that g transforms into b at a pressure of about 4 GPa at room temperature (Tan et al, 2012). It implies that form b would be more stable than g above 4 GPa.…”

High Pressure Structural Investigation of Benzoic Acid: Raman Spectroscopy and X-ray Diffraction

“…This high-pressure behavior can also be found in pyrazinamide polymorphs. 49 The energy for structural transformation of BA is not high enough in this pressure range, and thus cannot cross the barriers. The present results may be helpful in exploring the stability of molecular crystals and pressure can be potentially applied in the pharmaceutical industry.…”

A room-temperature refuelable lithium, iodine and air battery

“…As discussed in our previous study 12 , can be formed in a two-step process according to x value of Li. With x  < 1, forms first together with unlithiated :With x  > 1, the system consists of a mixture of and :where 1 <  x  < 2.…”

“…The preparation of the Li-SES is carried out in an Ar-filled glove box at ambient temperature. Details of the preparation process are provided in our previous studies 12, 27 . The liquid-state active cathode material (catholyte) is made up of 0.1 M of I 2 in methanol.…”