Morphology of L-Alanine Crystal, Associated with its Interaction with Glycine Additive: A Molecular Modelling and Experimental Study

Abstract

. In this paper, L-alanine crystal was crystallized in the presence and absence of glycine additive using slow evaporation method, in association with a simulation technique using ab-initio quantum mechanical method used to predict the crystal morphology of L-alanine. Comparison between the experimental and simulated lattice energies have shown a good agreement with the 8% error, thus validating the set of force field and the partial atomic charges used. Attachment energy method used by the simulation to predict the morphology of L-alanine crystal, revealed a prismatic crystal morphology bounded with 10 dominant faces: (110), ( 0), ( 10), (1 0), (020), (0 0) (011), (0 ), (0 1) and (01 ), which is in good agreement with the experimental morphology. Crystallization of L-alanine in the presence of glycine in the solution also resulted in prismatic crystal morphology, but elongated in the z-axis direction. This result was further explained by intermolecular bonding analysis of glycine on the morphological faces of L-alanine crystal, which suggested that glycine was preferentially adsorbed on the (0 ) and (1 0) faces of L-alanine crystal morphology.