Biased Helical Folding of Chiral Oligoindole Foldamers
journal contributionposted on 04.12.2008, 00:00 by Veluru Ramesh Naidu, Min Cheol Kim, Jae-min Suk, Ho-Joong Kim, Myongsoo Lee, Eunji Sim, Kyu-Sung Jeong
Oligoindole-based chiral foldamers have been synthesized by incorporating (S)- or (R)-1-phenylethylamine to both ends of the tetraindole scaffold. The oligoindoles fold into a helical conformation upon binding an anion by hydrogen bonds, which gives rise to an induced circular dichroism (CD) signal of large amplitude, implying the preferential formation of one helical isomer over another. Theoretical calculations suggest that the (P)-helix of the (S,S)-oligoindole 8a be more energetically stable than the corresponding (M)-helix.