Temperature-induced chiroptical changes in a helical poly(phenylacetylene) bearing N,N-diisopropylaminomethyl groups with chiral acids in water.
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.
Nagai
Kanji
K
Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan.
Maeda
Katsuhiro
K
Takeyama
Yoshihisa
Y
Sato
Takahiro
T
Yashima
Eiji
E
D000114:Acetylene / Q000031:analogs & derivatives* / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry*; D002942:Circular Dichroism; D008968:Molecular Conformation; D013237:Stereoisomerism; D013451:Sulfonic Acids / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry
D002264:Carboxylic Acids; D013451:Sulfonic Acids; C519145:poly(phenylacetylene); D014867:Water; D000114:Acetylene