Crystal Growth of Pharmaceuticals from Melt

Phase State and Saturation Vapor Pressure of Submicron Particles of meso-Erythritol at Ambient Conditions

“…As discussed in Bilde et al (2015) 14 the difference in vapor pressure of the amorphous solid and the subcooled liquid state of secondary organic aerosol species is in most cases negligible, and may be estimated using the change in heat capacity at the glass transition temperature. For meso-erythritol, the glass transition temperature is reported to be 228 K, and the associated change in heat capacity is reported to be 0.1 J K −1 mol −1 , 48 resulting in a ratio of amorphous to subcooled liquid vapor pressure at 298 K of 0.99. For meso-erythritol, it is thus expected that particles in a subcooled liquid state and particles in an amorphous solid state will behave the same with respect to evaporation in the flow tube, i.e., these two states cannot explain the observed bimodal behavior.…”

Investigating Differences and Similarities between Betaxolol Polymorphs

“…Distance (Å) Angle (°) X-H … Y X … Y H … Y X-H … Y O2-H2o ... N1 2 2.786(3) 1.84 (3) 167(3) N1-H1n … O2 3 3.038(3) 2.22 3157(2) C-H…π H … (C6)centroid (Å) CH … (C6)centroid (°) C7-H7a … (C1-C6) 4 centroid 2.78 3132 21 geometrical data refer to X-ray diffraction data collected at 100K; 2 = x + 1/2, −y,+z; 3 = −x + 3/2, + y,−z + 1; 4 = x−1/2, −y, z.…”

“…For a given compound, only the form having the lowest Gibbs energy is thermodynamically stable. However, in some cases, due to the height of the energy barrier separating some polymorphs and the most stable one, the metastable forms remain stable for a period of time long enough to be used for practical purposes as if they were stable forms [1,2]. There are cases where obtaining a given polymorph is very difficult even if this solid form had previously been usually obtained for long time.…”

“…geometrical data refer to X-ray diffraction data collected at 100K;2 = x + 1/2, −y,+z; 3 = −x + 3/2, + y,−z + 1; 4 = x−1/2, −y, z.…”