Supercooled liquid during the evaporation and cooling crystallization of valsartan: a macroscopic observation

Abstract

Macroscopic observation is an interesting topic in the field of non-classical crystallization. Because the glass transition temperature (T_g) of organic molecules is usually not high and can be further decreased by solvation, it is necessary to distinguish between supercooled liquids and amorphous solids during the crystallization process of organic molecules. The difference in the fluidity between these two phases makes it possible to distinguish them through a macroscopic observation. The transition process from a supercooled liquid precursor to the amorphous phase was observed without any additive during the evaporation crystallization process of valsartan in ethanol, as well as in the evaporation crystallization process of glucose in water, via visual inspection of fluidity and fluorescent probe method, and was also observed during the cooling crystallization process of valsartan in water via dissolution experiment and fluorescent probe method. More examples are needed to further refine the principle by which supercooled liquid precursors undergo a transformation to amorphous solids during the crystallization process of organic molecules.