Work

Crystal Engineering of l -Alanine with l -Leucine Additive using Metal-Assisted and Microwave-Accelerated Evaporative Crystallization

Year: 2014

Type: article

Abstract: In this work, we demonstrated that the change in the morphology of l-alanine crystals can be controlled with the addition of l-leucine using the metal-assisted and microwave accelerated evaporative crystallization (MA-MAEC) technique. Crystallization experiments, where an increasing stoichiometric amount of l-leucine is added to initial l-alanine solutions, were carried out on circular poly(methyl methacrylate) (PMMA) disks modified with a 21-well capacity silicon isolator and silver nanoparticle films using microwave heating (MA-MAEC) and at room temperature (control experiments). The use of the MA-MAEC technique afforded for the growth of l-alanine crystals with different morphologies up to ∼10-fold faster than those grown at room temperature. In addition, the length of l-alanine crystals was systematically increased from ∼380 to ∼2000 μm using the MA-MAEC technique. Optical microscope images revealed that the shape of l-alanine crystals was changed from tetragonal shape (without l-leucine additive) to more elongated and wire-like structures with the addition of the l-leucine additive. Further characterization of l-alanine crystals was undertaken by Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy and powder X-ray diffraction (PXRD) measurements. In order to elucidate the growth mechanism of l-alanine crystals, theoretical simulations of l-alanine's morphology with and without l-leucine additive were carried out using Materials Studio software in conjunction with our experimental data. Theoretical simulations revealed that the growth of l-alanine's {011} and {120} crystal faces were inhibited due to the incorporation of l-leucine into these crystal faces in selected positions.

Source: Crystal Growth & Design

DOI: 10.1021/cg500204t

Authors: Adeolu Mojibola, Gilles Dongmo-Momo, Muzaffer Mohammed, Kadir Aslan

Institution: Morgan State University

Language: English

Topic: Crystallization and Solubility Studies

Subfield: Materials Chemistry

Field: Materials Science

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,500

Funders: National Institutes of Health, National Institute of General Medical Sciences, National Institute of Biomedical Imaging and Bioengineering