Cyclomaltooligosaccharide-assisted spectroscopic discrimination of phthalimido-derived amino acids through the formation of molecular aggregates.
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.
Jursic
Branko S
BS
Department of Chemistry, University of New Orleans, New Orleans, LA 70148, USA. bsjcm@uno.edu
Patel
Paresh K
PK
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*
D000596:Amino Acids; D003505:Cyclodextrins; D046911:Macromolecular Substances; D014364:Tryptophan