Cyclomaltooligosaccharide-assisted spectroscopic discrimination of phthalimido-derived amino acids through the formation of molecular aggregates |
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Authors: | Jursic Branko S Patel Paresh K |
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Affiliation: | Department of Chemistry, University of New Orleans, New Orleans, LA 70148, USA. bsjcm@uno.edu |
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Abstract: | Spectroscopic evidence was used to demonstrate the formation of molecular associates in an aqueous solution of phthalimido tryptophan. These molecular associates are loosely formed through pi-pi aromatic stacking, properties that are not sufficient to cause NMR spectroscopic enantiomeric discrimination. A cyclomaltooligosaccharide with a larger cavity, such as cyclomaltooctaose (gamma-cyclodextrin), is capable of forming a ternary complex with these molecular associates and enhances pi-pi aromatic stacking interactions, resulting in NMR enantiomeric discrimination. Electrospray-ionization mass spectroscopy (ESIMS) and NOESY two-dimensional NMR spectroscopic methods were used to study these complexes. Association constants and thermodynamic data for these cyclomaltooligosaccharide complexes were also estimated. |
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Keywords: | Cyclomaltooligosaccharide Enantiomeric discrimination Molecular aggregation ESIMS |
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