Title :
Probing solids through THz spectroscopy: Differentiation of chiral and racemic forms of isostructural and non-isostructural cocrystals
Author :
Edward P. J. Parrott;J. Axel Zeitler;Tomislav Friscic;Michael Pepper;William Jones;Graeme M. Day;Lynn F. Gladden
Author_Institution :
Department of Chemical Engineering, University of Cambridge, Pembroke St., CB2 3RA, U.K.
Abstract :
Cocrystals of theophylline (tp) and racemic and chiral forms of both tartaric acid (tart) and malic acid (mal) were investigated using terahertz time-domain-spectroscopy (THz-TDS). Using X-ray powder diffraction (XRPD) the racemic and chiral malic acid cocrystal forms were found to be nearly isostructural and therefore almost indistinguishable using XRPD. Using THz-TDS clear differences were observed both at room temperature and at 109 K. This was rationalized using lattice energy calculations and attributed to a difference in the conformational strain of the acid groups between the two cocrystal forms.
Keywords :
"Lattices","Crystals","Spectroscopy","Probes","Solids","Time domain analysis","Diffraction"
Conference_Titel :
Infrared, Millimeter and Terahertz Waves, 2008. IRMMW-THz 2008. 33rd International Conference on
Print_ISBN :
978-1-4244-2119-0
Electronic_ISBN :
2162-2035
DOI :
10.1109/ICIMW.2008.4665756