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Crystallography: Deep Understanding the Mechanism of β-form Nucleation in Cooling Crystallization of L-glutamic Acid

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This result was confirmed via the molecular simulation, in which the functional groups of molecule on various surfaces of α-form crystal were different, so the degree of lattice matching (E) between the α-form substrate surfaces and β-form molecule aggregate was distinguished and ordered as (001) > (011) > (111), meaning that the nucleation of heterogeneous β-form was more facilitated on the (001) and (011) surfaces compared to that on the (111) surface of α-form crystal. | Vietnam Journal of Chemistry, International Edition, 54(4): 515-519, 2016 DOI: 10.15625/0866-7144.2016-00357 Crystallography: Deep Understanding the Mechanism of β-form Nucleation in Cooling Crystallization of L-glutamic Acid Dang Truong Giang, Khuu Chau Quang, Trinh Thi Thanh Huyen*, Nguyen Anh Tuan Institute of Chemical Technology, Vietnam Academy of Science and Technology Received 25 February 2016; Accepted for publication 12 August 2016 Abstract The mechanism of heterogeneous β-form nucleation was investigated during the phase transformation of L-glutamic acid in the stirring cooling crystallization. In the present study, a new mechanism of heterogeneous β-form nucleation was explored, where the β-form nuclei was favorably crystallized on the (001) and (011) surfaces rather than the (111) surface of α-form crystal during the phase transformation. This result was confirmed via the molecular simulation, in which the functional groups of molecule on various surfaces of α-form crystal were different, so the degree of lattice matching (E) between the α-form substrate surfaces and β-form molecule aggregate was distinguished and ordered as (001) > (011) > (111), meaning that the nucleation of heterogeneous β-form was more facilitated on the (001) and (011) surfaces compared to that on the (111) surface of α-form crystal. Keywords. Crystallization, crystallography, polymorphism, nucleation, crystal growth. 1. INTRODUCTION Crystallization is very important separation, purification and particle synthesis process used widely in pharmaceutical, chemical, and food industries, etc [1]. In the pharmaceutical industry, there are more than 90% of all pharmaceutical products containing the active pharmaceutical ingredients (API) in crystalline forms. As such, crystallization process is certainly required to make the phase transition of molecules from the solution to the solid state. Plus, the orderly structured crystalline facilitates impurity rejection from the solid .