Identification and Structural Studies of the Salicylic Acid DL-Phenylalanine Cocrystal
[1]
Mohamed Atiega Elbagerma, Department of Chemistry, Faculty of Science, University of Misurata, Misurata, Libya.
[2]
Howell GM Edwards, Department of Chemical and Forensic Sciences, Faculty of Life Sciences, University of Bradford, Bradford, UK.
[3]
Adel Imhemed Alajtal, Department of Chemistry, Faculty of Science, University of Misurata, Misurata, Libya.
[4]
Ian Ja Scowen, School of Chemistry, College of Science, University of Lincoln, Lincoln, UK.
This paper reports the synthesis, experimental study of a novel organic-organic cocrystal energetic material. The molecular and crystal structures of cocrystal are determined by means of x-ray powder diffraction (XRD)/X-ray crystallography, Raman spectroscopy and differential scanning calorimetry. Raman spectroscopy was particularly useful for characterization of the products and was used to determine the nature of the interaction in the cocrystals. Several new vibrational bands were identified in the cocrystal which were not manifest in the raw material and could be used as diagnostic features of cocrystal formation. An understanding of the effects of cocrystal formation on the vibrational mode was obtained by complete assignment of the spectra of the starting material and of cocrystal component. Single crystal X- ray studies confirmed the formation of a cocrystal with a 1:1 stoichiometry between salicylic acid and DL-phenylalanine. The asymmetric unit of the cocrystal contains four molecules: two molecules of salicylic acid and both R- and S- enantiomers of phenylalanine. Each of the phenylalanine molecules is in the zwitterion form.
Cocrystals, Raman Spectroscopy, Salicylic Acid, Single-Crystal and X-ray Diffraction
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