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Temperature‐Induced Chiroptical Changes in a Helical Poly(phenylacetylene) Bearing N , N ‐Diisopropylaminomethyl Groups with Chiral Acids in Water
Author(s) -
Nagai Kanji,
Maeda Katsuhiro,
Takeyama Yoshihisa,
Sato Takahiro,
Yashima Eiji
Publication year - 2007
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.200700185
Subject(s) - phenylacetylene , circular dichroism , enantiomer , chirality (physics) , optical rotation , chemistry , cotton effect , polymer , dynamic light scattering , enantiomeric excess , polymer chemistry , pendant group , amino acid , crystallography , stereochemistry , materials science , organic chemistry , enantioselective synthesis , chiral symmetry , nanotechnology , catalysis , biochemistry , nambu–jona lasinio model , physics , quantum mechanics , nanoparticle , quark
A stereoregular poly(phenylacetylene) bearing an N , N ‐diisopropylaminomethyl group as the pendant (poly‐ 1 ) changed its structure into the prevailing one‐handed helical conformation upon complexation with optically active acids in water. The complexes exhibited induced circular dichroism (ICD) in the UV/Vis region of the polymer backbone. Poly‐ 1 is highly sensitive to the chirality of chiral acids and can detect a small enantiomeric imbalance in these acids, in particular, phenyl lactic acid in water. For example, a 0.005 % enantiomeric excess of phenyl lactic acid can be detected by CD spectroscopy. The observed ICD intensity and pattern of poly‐ 1 were dependent on the temperature and concentration of poly‐ 1 , probably due to aggregations of the polymer at high temperature as revealed by dynamic light scattering and AFM. On the basis of the temperature‐dependent ICD changes, the preferred chiral helical sense of poly‐ 1 was found to be controlled by noncovalent bonding interactions by using structurally different enantiomeric acids.