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Spontaneous chirality conversion of [5]thiaheterohelicene in charge‐transfer complexes in SDS micelles
Author(s) -
Nakagawa Hiroko,
Kobori Yuuki,
Yamada KohIchi
Publication year - 2001
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.10009
Subject(s) - chemistry , chirality (physics) , micelle , enantiomer , circular dichroism , conformational change , aqueous solution , crystallography , stereochemistry , photochemistry , organic chemistry , physics , chiral symmetry breaking , quantum mechanics , nambu–jona lasinio model , quark
Racemic 2‐hydroxymethylthieno[3,2‐e:4,5‐e′]di[1]benzothiophene (5HM) with a labile helical structure was incorporated into aqueous SDS micelles containing (R)‐2‐(2,4,5,7‐tetranitrofluoren‐9‐ylideneaminooxy)propionic acid (TAPA) to exhibit intense induced CD (ICD). Negative Cotton effects of the ICD gradually changed to reversed Cotton effects with time or sonication. This phenomenon of chirality conversion was attributable to conformational alterations of 5HM from an (M) helix to a (P), accompanied by compositional alterations of 5HM–(R)‐TAPA charge‐transfer (CT) complexes from 1/2 to 1/1. The conversion rate from the (M) enantiomer to the (P) was obtained from the change of the ICD intensities with time and the chiral discrimination energy exerted in the 1:1 CT complex was estimated from the temperature dependence of the ICD intensities. Chirality 13:722–726, 2001. © 2001 Wiley‐Liss, Inc.