title: Cyclomaltooligosaccharide-assisted spectroscopic discrimination of phthalimido-derived amino acids through the formation of molecular aggregates.
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.
authors.affiliation: Department of Chemistry, University of New Orleans, New Orleans, LA 70148, USA. bsjcm@uno.edu
authors.forename: Branko S
authors.initials: BS
authors.lastname: Jursic
authors.forename: Paresh K
authors.initials: PK
authors.lastname: Patel
mesh_terms: D000596:Amino Acids / Q000737:chemistry* / Q000145:classification* / Q000302:isolation & purification; D003505:Cyclodextrins / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008968:Molecular Conformation; D010316:Particle Size; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D014364:Tryptophan / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D003505:Cyclodextrins; D046911:Macromolecular Substances; D014364:Tryptophan