Can We Predict the Isosymmetric Phase Transition? Application of DFT Calculations to Study the Pressure Induced Transformation of Chlorothiazide.

Łukasz Szeleszczuk,Ewa Napiórkowska,Anna Helena Mazurek,Dariusz Maciej Pisklak,Katarzyna Milcarz

doi:10.3390/ijms221810100

Łukasz Szeleszczuk, Ewa Napiórkowska + Show 3 more

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https://doi.org/10.3390/ijms221810100

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Abstract

Isosymmetric structural phase transition (IPT, type 0), in which there are no changes in the occupation of Wyckoff positions, the number of atoms in the unit cell, and the space group symmetry, is relatively uncommon. Chlorothiazide, a diuretic agent with a secondary function as an antihypertensive, has been proven to undergo pressure-induced IPT of Form I to Form II at 4.2 GPa. For that reason, it has been chosen as a model compound in this study to determine if IPT can be predicted in silico using periodic DFT calculations. The transformation of Form II into Form I, occurring under decompression, was observed in geometry optimization calculations. However, the reverse transition was not detected, although the calculated differences in the DFT energies and thermodynamic parameters indicated that Form II should be more stable at increased pressure. Finally, the IPT was successfully simulated using ab initio molecular dynamics calculations.

Highlights

Polymorphism, commonly defined as the ability of a substance to exist as two or more crystalline phases that have different arrangements or conformations of the molecules in the crystal lattice [1] is a phenomenon with particular importance in the pharmaceutical sciences and industry
Isosymmetric structural phase transition (IPT, type 0), in which there are no changes in the occupation of Wyckoff positions, the number of atoms in the unit cell, and the space group symmetry are relatively uncommon [5]
The first set of calculations (Table S1) was performed to find out how the choice of the density functional theory (DFT) functional would affect the accuracy of geometry optimization and to choose the most accurate one for the subsequent calculations

Summary

Introduction

Polymorphism, commonly defined as the ability of a substance to exist as two or more crystalline phases that have different arrangements or conformations of the molecules in the crystal lattice [1] is a phenomenon with particular importance in the pharmaceutical sciences and industry. For the correct design of a pharmaceutical compound, it is, crucial to control its solid-state form to guarantee its properties. The application of high pressure has been shown as a route to access new phases of solid-state materials—possibly the most famous example being the transformation of graphite into diamond [4]. Pressure-induced phase transition can occur in a single step between higher- and lower-symmetry space groups (type I), through a low-symmetry transition state between relatively higher- symmetry initial and final structures (type II), or via the transformation in which the mechanism is more complex (type III).

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