Single-crystal-to-single-crystal phase transition of 18β-glycyrrhetinic acid isopropyl ester

Abstract

Due to the destruction of the integrity of the parent crystal, single-crystal-to-single-crystal phase transition in organic compounds is still a relatively rare phenomenon. The phase transition in glycyrrhetinic acid isopropyl ester is triggered by temperature change. The increasing volume of the isopropyl substituent as a result of increasing temperature forces a remodelling of the structural motifs. These changes cause a single-crystal-to-single-crystal phase transition. The low-temperature form is isostructural with glycyrrhetinic acid methanol solvate, while the high-temperature phase is isostructural with the ethyl ester of this acid.

Polymorphism of Butyl Ester of Oleanolic Acid—The Dominance of Dispersive Interactions over Electrostatic

“…In studied crystals, the assembly of molecules leads to the formation of hydrogen-bonded helices. This 1D motif does not occur in layered structures based mainly on van der Waals interactions [ 9 , 34 ].…”

“…Thus, discovering polymorphic forms of active substances cannot be overestimated, but it is not a straightforward task. Factors such as impurities, additives, solution saturation, solution mixtures, thermodynamics, and many others can influence crystallization processes and are difficult to control [ 2 , 8 , 9 ]. Numerous methods are employed for polymorph screening, e.g., recrystallization, slurrying, cooling crystallization, sublimation, lyophilization, grinding, compression, or template-inducing nucleation [ 10 , 11 , 12 , 13 , 14 ].…”

“…These 1D motifs assembly into layers of two types that are characteristic of each kind of ribbon. Similar 1D and 2D motifs are also basic structural units in crystal structures of GE solvates, GE esters, and carbenoxolone [ 9 , 35 , 36 , 37 , 38 , 39 ].…”

Solid-To-Solid Polymorphic Phase Transitions in Two Isostructural Bi(III) Complexes With 1-Phenylethyl-N-Ethylthiosemicarbazide and Halogens

“…Phase transition materials (PTMs) usually display abrupt modi cations of physical properties [3] around the temperature of conversion and are considered functional materials, such as switchable and tunable dielectrics [3,4], multiferroics [5], and ferroelectrics [6]. Consequently, the eld of interest in the case of PTM is very broad and covers inorganic [7,8], metalloorganic [5,9,10] and organic compounds [11][12][13][14]. Understanding the full mechanism of solidsolid transitions and, consequently, the possibility of controlling the process of obtaining de facto different polymorphs is particularly important in the pharmaceutical industry mainly due to the possible difference in physicochemical or biological properties such as solubility, bioavailability or even activity, which also in uences the formal and economic factors.…”