Induced circular dichroism , poly chiral

Treatment of a number of covalent polymers substituted with molecular recognition capability with suitable guests leads to chiral induction. The same crown ether-amino acid complementary pair described for the rosettes above was employed in the form of crown-ether pendant cis-transoidai poly(phenylacetylene). When the achiral polymer is treated with amino acids (in the form of their hydroperchlorate salts in acetonitdle) a large induced CD signal is observed in the backbone of the polymer. The polymer is sensitive to small enantiomeric excesses in the amino acid, as little as 0.005% enantiomeric excess of alanine can be detected. In a similar vein, c/5-transoidal poly(carboxyphenylacetylene) shows induced circular dichroism when treated with nonracemic chiral amines In addition, the system displays chiral memory, in that treatment of the complex with achiral amino alcohols results in retention of the chiral polymer backbone. 

Before discussing the remarkable kinetic inertia of these ternary species it is useful to present the main characteristic of the CuT4-poly-glutamate binary system. The binary complex is chiral and kinetically labile. This is shown by (1) the presence of an induced band in the Soret region of the circular dichroism (CD) spectra (inset of Fig. 3, curve a) and (2) the inversion (in about 10 min) of the same... 

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