Strategic Construction of Chiral Helices: Expanded Poly(l‑leucine) Containing p‑Phenylene Moieties

A series of expanded oligo- and poly­(l-leucine)­s, with an alternating arrangement of p-phenylene moieties and l-leucine residues, were synthesized by stepwise elongation or polycondensation and characterized by 1H NMR, SEC, ESI-MS, UV, and CD spectra. The degree of polymerization was found to be a...

Full description

Saved in:
Bibliographic Details
Published inMacromolecules Vol. 50; no. 9; pp. 3500 - 3509
Main Authors Okamura, Taka-aki, Seno, Shuichiro
Format Journal Article
LanguageEnglish
Published American Chemical Society 09.05.2017
Online AccessGet full text

Cover

More Information
Summary:A series of expanded oligo- and poly­(l-leucine)­s, with an alternating arrangement of p-phenylene moieties and l-leucine residues, were synthesized by stepwise elongation or polycondensation and characterized by 1H NMR, SEC, ESI-MS, UV, and CD spectra. The degree of polymerization was found to be about 19 by SEC. Each monomer unit, i.e., expanded l-leucine, behaved like a chiral unit with a rigid bend body. Elongation of the peptide chain significantly increased the CD intensity per phenylene chromophore; however, the CD intensity decreased at high temperatures. This cooperative behavior strongly suggested the formation of a secondary structure. 1H NMR analysis revealed a right-handed helical structure in dimethyl sulfoxide. The theoretical calculations were consistent with these results.
ISSN:0024-9297
1520-5835
DOI:10.1021/acs.macromol.7b00718