(692c) Effects of Inorganic Salts and Volume Reduction on Glycine Polymorphism
Studies have demonstrated that inorganic salts can drive polymorphic selectivity of glycine from the metastable Î±-polymorph to the stable Î³-polymorph. Here, we explore the effect of NaCl and CaCl2 together with volume reduction on glycine nucleation. The salts were added to supersaturated aqueous solutions of glycine at a 2:1 Gly:NaCl/CaCl2 ratio at volumes from 1000 Î¼L to 50 Î¼L. Analysis showed that a primary Î³-glycine nucleation event occurs for Gly:NaCl systems, with observed increase in induction times as volume was decreased. However, Î²-glycine primary nucleation was also detected for Gly:NaCl systems. Interestingly, it was observed that Î²-glycine nucleation is preferred over the salt-directed Î³-glycine nucleation at a certain volume. The increase in induction times combined with a decrease in probability for Î³-glycine nucleation may have allowed preferred nucleation of the Î²-polymorph. On the other hand, no nucleation events were observed for Gly:CaCl2 systems at a time span of 48 hours. These results provide insight on how polymorph modifiers act in confined environments.