ABSTRACT
This chapter addresses the basic principles necessary for an understanding of the technique and the phenomenological equations necessary to use it. It discusses the complex quantum mechanical treatment necessary for theoretical predictions of optical activity. The chapter describes how optical activity used in an empirical way to solve a variety of biological problems. The octant rule has enjoyed particular success in predicting sign and relative intensity of the circular dichroism (CD) spectra of carbonyl compounds. Other sector rules have been developed for other chromophores. The absorption of a helical polymer corresponding to the degenerate interactions of an intense transition of the chromophore consists of two allowed transitions at slightly different energies. One corresponds to light linearly polarized along the helix axis, and the other corresponds to light linearly polarized perpendicular to the helix axis. The conformation of an oligomer will often vary with chain length. The effect has been conveniently monitored for all types of biological molecules using CD spectroscopy.
