Self-association of an enantiopure β-pentapeptide in nematic liquid crystals.
Herein, we report for the first time that nematic liquid-crystalline environments drive the reversible self-aggregation of an enantiopure β-pentapeptide into oligomers with a well-defined structure. The peptide contains four (1S,2S)-2-aminocyclopentane carboxylic acid (ACPC) residues and the paramagnetic β-amino acid (3R,4R)-4-amino-1-oxyl-2,2,5,5-tetramethylpyrrolidine-3-carboxylic acid (POAC). The structure of the oligomers was investigated by electron paramagnetic resonance (EPR) spectroscopy, which allowed us to obtain the intermonomer distance distribution in the aggregates as a function of peptide concentration in two nematic liquid crystals, E7 and ZLI-4792. The aggregates were modeled on the basis of the EPR data, and their orientation and order in the nematic phase were studied by the surface tensor method.
Department of Chemical Sciences, University of Padova, 35131 Padova (Italy), Fax: (+39) 049-827-5050.
Marco
M
Bortolus
Karen
K
Wright
Antonio
A
Toffoletti
Claudio
C
Toniolo
Anna Lisa
AL
Maniero
D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D050866:Liquid Crystals / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*
D010455:Peptides
EPR spectroscopy; liquid crystals; oligomerization; peptides; self-assembly