Self-Assembling Cyclic Tetrapeptide from Alternating C-Linked Carbo-β-amino Acid [(<i>S</i>)-β-Caa] and α-Aminoxy Acid [(<i>R</i>)-Ama]: A Selective Chloride Ion Receptor

Abstract

A cyclic tetrapeptide is prepared from alternating (S)-beta-Caa (C-linked carbo-beta-amino acid) and (R)-Ama (alpha-aminoxy acid). Extensive NMR (in CDCl(3) solution) and mass spectral (MS) studies show its halide binding capacity, with a special affinity to the chloride ion. At higher concentration it was found to form molecular aggregates as evidenced from transmission electron microscopic and atomic force microscopic analysis, confirming the formation of nanorods.