Issue 23, 2013

Insights into the polymorphism of glycine: membrane crystallization in an electric field

Abstract

In this work we studied glycine crystallization with two main objectives: (i) to get improved control of crystal growth and polymorphic selectivity of organic molecules; (ii) to achieve additional insights into the nucleation mechanisms of glycine polymorphs. To reach these goals, membrane crystallization technology, a tool which allows improved control of supersaturation in solution crystallization, was used under different operating conditions: the variable solvent removal rate, acidic and almost neutral pH, the presence of a pulsed electric field. The traditional explanation for the crystallization of α and γ glycine polymorphs from aqueous solution is based on the general cyclic dimer hypothesis and the self-poisoning mechanism. In contrast with both the conventional theories, experimental results suggest that the relative nucleation rates with respect to the relative growth kinetics of the two forms under the different conditions play a dominant role in determining the polymorphic outcome. Our results instead support a molecular nucleation route where open chain dimers can behave as building units for both γ- and α-glycines in the rate determining structuring step of the two-step nucleation mechanism.

Graphical abstract: Insights into the polymorphism of glycine: membrane crystallization in an electric field

Article information

Article type
Paper
Submitted
14 Feb 2013
Accepted
15 Apr 2013
First published
09 May 2013

Phys. Chem. Chem. Phys., 2013,15, 9271-9280

Insights into the polymorphism of glycine: membrane crystallization in an electric field

G. Di Profio, M. T. Reijonen, R. Caliandro, A. Guagliardi, E. Curcio and E. Drioli, Phys. Chem. Chem. Phys., 2013, 15, 9271 DOI: 10.1039/C3CP50664A

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