Probing Intermolecular Interactions in Chiral Chromatography with NMR Spectroscopy
Abstract
NMR spectroscopy was used to probe the intermolecular interactions in chiral chromatography. Three chiral sypathiometric analytes were studied; ephedrine, norephedrine, and pseudoephedrine along with a chiral surfactant; N-dodecocycarbonylvaline (DDCV). One dimensional diffusion experiments were performed to determine the complex with the greatest binding constant. Two dimensional ROESY experiments were collected to determine the intermolecular and intramolecular interactions of the analyte:surfactant mixtures and to generate binding maps. Experimental results determined that ephedrine exhibited stronger binding to the micelles than the pseudoephedrine. The norephedrine:DDCV association constants spanned a wider range than ephedrine or pseudoephedrine. The two-dimensional ROESY data suggested that one strong H-bond between the analyte and the micelle produced a lower energy complex than two weak H-bond and/or two competing H-bonds between the –OH and the –NH donor sites on the analyte. The two-dimensional ROESY data also suggested that once the analyte is H-bonded to the micelle, the analyte remained near the micelle surface within the chiral pocket, with the aromatic ring pointing towards the hydrocarbon chain, rather than interacting with the hydrophobic core of the micelle.
Collections
Related items
Showing items related by title, author, creator and subject.
-
Single Walled Carbon Nanotube purification techniques evaluated by Raman and Infrared Spectroscopy, and Nanotube application in Gas Chromatography
Jaeger, Kyle (2012-05-15)Understanding how purification steps affect single walled carbon nanotubes (SWNTs) is vital to further use of these nanotubes in other chemical techniques such as gas chromatography (GC), synth ... -
Measuring the Correlation Times of Molecules Bound to Chiral Molecular Micelles
Hamerly, Tim (2010-09-09)NMR spectroscopy was used to determine the correlation times of 1,1'- binaphthyl-2,2'-diyl hydrogen phosphate (BNP) protons when bound to molecular micelles. These molecular micelles contained a dipeptide head group composed ... -
Astronomical Applications of Remote Sensing: A Search for Diffuse Interstellar Band Absorption Features
Nicklaus, Jennifer (2013-09-06)At first glance geography and astronomy have nothing in common, but upon further review, astronomy shares many of the same principles of remote sensing. Both rely on data obtained indirectly from distant sources and both ...