The effect of linear anisotropies on the CD spectrum: Is it true that the oriented polyvinyalcohol film has a magic chiral domain inducing optical activity in achiral molecules?

Abstract

AbstractRecent publication of the induced CD studies by Ritcey and Gray [(1988) Biopolymers 27, 1363–1374] states that the Congo red dye bound to regenerated cellulose in highly swollen gel films formed shows induced optical activity, reflecting the chiral molecular arrangement of the cholesteric structure. In this paper, we show that this conclusion is erroneous owing to a misinterpretation of the experimental results. We point out in detail where the errors were committed, and present our experimental data to prove that the average CD signal obtained with using the method of Tunis‐Schneider and Maestre [(1970) J. Mol. Biol. 52, 521–541] can never be regarded as the true induced CD signal. We further present the result of analyzing our data with the Mueller matrix approach to confirm our conclusion. We repeat the conclusion of our previous paper [(1985) J. Am. Chem. Soc. 107, 91–97] that the CD spectra observed in cholesteric liquid structure cannot provide us with the proof showing the optical activity induced in achiral molecules.