Anomalous optical rotatory dispersion curve

Optical rotatory dispersion (ORD) involves the measurement of the rotation of plane-polarized light by a chiral compound as a function of the wavenumber. Circular dichroism (CD) is the unequal absorption of right and left circularly-polarized light as a function of its wavenumber. CD and anomalous ORD curves observed for chiral solute... 

Figure 15. Circular dichroism curve (-—) plotted on the left-hand ordinate and optical rotatory dispersion (ORD) curve (-—) plotted on the right-hand ordinate of d-camphor-10-sulfonate. It is seen that the band width at [df]/e and the distance between the ORD extrema coincide better than does the band width at [0 ]/2, i.e., r. The amplitude of the ORD anomalous dispersion curve (Cotton effect) is indicated as [Amp]. Reproduced, with permission, from [3].

As a consequence of a CD the normal plain curve of the wavelength dependence of a, the "optical rotatory dispersion" (ORD) becomes anomalous and the plain curve is superposed by an S-shaped curve. Both, CD and anomalous ORD, are called "Cotton effect". Quantitatively CD and ORD are linked through the Kronig-Kramers relationship. No stringent coupling of the extinction coefficient (Emax) with the CD effect exists, because contains... 

O BRIEN and TOOLE (1) studied the.optical rotatory dispersion (ORD) of complexes formed by several colorless metal ions with optically active amines. They concluded that the effects were independent of the nature of the central metal ion and of the nature of the active amines, but dependent on the number of ligand molecules coordinated. SHIMURA (2) showed that for [Co(NHj) -leuc] (C10 )j [leuc a NHj,CH(CO )CjHj(CHj)j] the presence of the optically active ligand caused an anomalous dispersion curve in the region of the first absorption band of Co(III), The present paper reports the study of the contributions to the optical activity from the dissymmetric spiral configuration... 

Figure 10 shows the relationships between the spectral behavior of the two polarized beams with respect to rotation, absorption, and refraction. Only optically active substances interact differently with two polarized beams, so that this difference leads to observable effects. Whereas in the region of anomalous rotatory dispersion the ORD curve shows a point of inflection, the CD curve has a maximum or minimum [38]. The extreme of the CD curve coincides approximately with the point of inflection of the ORD curve. In analogy... 

Figure 4 Optical rotatory curves, as would be obtained for simple dispersion (both positive and negative curves are shown) and anomalous dispersion (illustrating a positive Cotton effect).

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