The polymorphic phase transformations in resorcinol at high pressure

Abstract

Abstract. Measurements of spin-lattice relaxation time T 1 for resorcinol have been made by the proton NMR technique using the saturation method in the temperature range 280 -380 K and pressure up to 800 MPa. The pressure-induced -β transition evolved through two phase coexistence range was observed. The crystal structure and vibrational spectra of the resorcinol have also been studied by means of X-ray diffraction and Raman spectroscopy at pressures up to 19 GPa in temperature range 290 -380 К. In experiments with a rapid pressurization rate, suppression of α-β polymorphic transition in resorcinol occurs. In experiments with a slow pressurization rate, two structural phase transitions, between orthorhombic α and β phases at P = 0.4 GPa and from β to another orthorhombic  phase at P=5.6 GPa, were observed. At pressures above 12.5 GPa, a gradual transformation to the amorphous phase was revealed. The lattice parameters, unit cell volumes and vibration modes as functions of pressure and temperature were obtained for the different polymorphic modifications of resorcinol.

The Polymorphic Phase Transformations in the Chlorpropamide under Pressure

“…The fitted values are B 0 = 20(3) GPa and B ′ = 4.0(5) for phase AI of chlorpropamide and B 0 = 27(1) GPa and B ′ = 4(0) for phase AII. The bulk module values of the pressure‐induced phases of chlorpropamide are slightly larger in comparison with the once obtained previously for form‐A ( B 0 ∼ 15 GPa), for form‐C ( B 0 ∼ 8 GPa) or for resorcinol crystal ( B 0 ∼ 11 GPa) . This fact can be explained by significant effect from inner stresses and strains due quasihydrostatic conditions in high‐pressure experiments.…”

The Pressure-Induced Polymorphic Transformations in Fluconazole

“…The fitted values are B 0 = 5(2) GPa and B ′ = 4(0) for form I and B 0 = 7(1) GPa and B ′ = 4(0) for form VIII of the fluconazole. The bulk module values for both forms of the fluconazole are somewhat smaller in comparison to those obtained previously for other pharmaceutical crystals: chlorpropamide ( B 0 ∼ 8 GPa) or resorcinol crystal ( B 0 ∼ 11 GPa) …”

Resorcinol Crystallization from the Melt: A New Ambient Phase and New “Riddles”

“…But, for polycrystalline samples, the determination of the structure of new polymorphs remains a challenge. , Herein, we determine the structure of a third form of crystalline resorcinol, the ε polymorph, by comparing computed structure predictions with available powder diffraction data. We had previously associated the third ambient pressure phase as γ, yet two high pressure phases have already claimed the γ and δ identifiers. − Therefore, we denote the new ambient phase ε.…”