Polymorphic forms of bendamustine hydro­chloride: crystal structure, thermal properties and stability at ambient conditions

Crystallographic, thermal and stability analyses are presented of three different anhydrated forms of bendamustine hydro­chloride [(I), (III) and (IV)] and a fourth, monohydrated one (II). Since form (I) presents the higher melting point and the higher heat of fusion, according to the 'heat of fusion' rule it should be the most stable in thermodynamic terms [Burger & Ramberger (1979). Mikrochim. Acta, 72, 259-271], though it is unstable in high-humidity conditions. The monohydrate structure (II), in turn, dehydrates by heating and topotactically transform into anhydrate (III). This latter form appears as less stable than anhydrate (I), to which it is linked via a monotropic relationship. For these three different forms, the crystal structure has been determined by single crystal X-ray diffraction. The crystal structures and molecular conformations of forms (II) and (III) are quite similar, as expected from the topotactic transformation linking them; furthermore, under high-humidity conditions, form (III) shows changes compatible with a transformation into form (II) within 24 h. The crystal structure of form (I) is different from the other two. The remaining polymorphic form (IV) could only be obtained as a powder, from which its crystalline structure could not be determined. The relative thermodynamic stability of the different crystalline forms was determined by differential scanning calorimetry and thermogravimetrical studies, and their stability under different humidity conditions analysed.Fil: Gaztañaga, Pablo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; ArgentinaFil: Baggio, Ricardo Fortunato. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Vega, Daniel Roberto. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentin

A crystallographic and thermal study of pridinol mesylate and its monohydrated solvate

Herein are reported the crystal and molecular structures of the pridinol mesylate salt (C20H25NO+·CH3O3S−) (I) and its monohydrated solvate form (C20H25NO+·CH3O3S−·H2O) (II). A comparison of both with the already reported structure of pure pridinol [1,1-diphenyl-3-piperidino-1-propanol, C20H25NO; Tacke et al. (1980). Chem. Ber.113, 1962–1980] is made. Molecular structures (I) and (II) are alike in bond distances and bond angles, but differ in their spatial conformation, and, more relevant still, in their hydrogen-bonding motifs. This gives rise to quite different packing schemes, in the form of simple dimers in (I) but water-mediated hydrogen-bonded chains in (II). The dehydration behaviour of form (II) is highly dependent on the heating rate, with slow rates leading to a clear endothermic dehydration step, towards anhydrous (I), with subsequent melting of this latter phase. Increased heating rates result in a more unclear behaviour ending in a structural collapse (melting of the hydrated phase), at temperatures significantly lower than the melting point of the anhydrous phase. The eventual relevance of the water link in the structure of (II) is discussed in regard to this behaviour.Fil: Gaztañaga, Pablo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Universidad Nacional de San Martín; ArgentinaFil: Baggio, Ricardo Fortunato. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Vega, Daniel Roberto. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Universidad Nacional de San Martín; Argentin

Thermal, spectroscopic and structural analysis of a thermosalient phase transformation in tapentadol hydrochloride

Presented herein are detailed optical, thermal, spectroscopic and structural analyses of the phase transformation occurring in tapentadol hydrochloride (C14H24NO+·Cl−), a phenomenon already reported [Fischer et al. (2006); Patent: WO 2006000441 A2]. The thermal behaviour of the compound was studied using single-crystal X-ray diffraction, differential scanning calorimetry and Raman scattering measurements. The compound undergoes a first-order reversible phase transition at Theat = 318.0 (1) K, Tcool = 300.0 (1) K, as assessed by the coexistence of both phases in the vicinity of the transition and the abrupt changes observed in the unit-cell parameters with temperature. The process is accompanied by clear thermosalient behaviour, with a conspicuous movement of the samples. On cooling, the transformation leads from a P212121 symmetry (Z′ = 1) to P21, with an abrupt change in β [90 ↔ 94.78 (1)°] and duplication of the asymmetric unit contents (Z′ = 2). The main structural differences observed across the transition are extremely small, with almost no changes in the stronger, non-covalent interaction scheme involving the `conventional' (N—H…Cl, O—H…Cl) hydrogen bonds.Presented herein are detailed optical, thermal, spectroscopic and structural analyses of the phase transformation occurring in tapentadol hydrochloride (C14H24NO+ Cl), a phenomenon already reported [Fischer et al. (2006); Patent: WO 2006000441 A2]. The thermal behaviour of the compound was studied using single-crystal X-ray diffraction, differential scanning calorimetry and Raman scattering measurements. The compound undergoes a first-order reversible phase transition at Theat = 318.0 (1) K, Tcool = 300.0 (1) K, as assessed by the coexistence of both phases in the vicinity of the transition and the abrupt changes observed in the unit-cell parameters with temperature. The process is accompanied by clear thermosalient behaviour, with a conspicuous movement of the samples. On cooling, the transformation leads from a P212121 symmetry (Z0 = 1) to P21, with an abrupt change in [90 $ 94.78 (1) ] and duplication of the asymmetric unit contents (Z0 = 2). The main structural differences observed across the transition are extremely small, with almost no changes in the stronger, non-covalent interaction scheme involving the ‘conventional’ (N—HCl, O— HCl) hydrogen bonds.Fil: Gaztañaga, Pablo Ernesto. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; ArgentinaFil: Baggio, Ricardo Fortunato. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; ArgentinaFil: Halac, Emilia Beatriz. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; ArgentinaFil: Vega, Daniel Roberto. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentin

Dynamic tuning by hydrostatic pressure of magnetocaloric properties to Ericsson like cycles

A method to increase the relative cooling power to be used in Ericsson like refrigeration cycles is presented. The technique is based in the modification of the magnetic properties by the application of hydrostatic pressure on magnetic samples. The main advantage is to reach larger values of the magnetic entropy change in a wider temperature region (the so-called “table like” behavior). The study was carried out in a manganite belonging to the family of La0.625−yNdyCa0.375MnO3, and some conclusions were compared with the expected behavior in other materials extracted from literature.Fil: Gaztañaga, Pablo Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Sacanell, Joaquin Gonzalo. Comisión Nacional de Energía Atómica; Argentina. Instituto de Nanociencia y Nanotecnología; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Leyva de Guglielmino, Ana Gabriela. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Instituto de Nanociencia y Nanotecnología; Argentina. Comisión Nacional de Energía Atómica; ArgentinaFil: Quintero, Mariano Horacio. Instituto de Nanociencia y Nanotecnología; Argentina. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentin