Rotatory strength, optical

A particularly useful probe of remote-substituent influences is provided by optical rotatory dispersion (ORD),106 the frequency-dependent optical activity of chiral molecules. The quantum-mechanical theory of optical activity, as developed by Rosenfeld,107 establishes that the rotatory strength R0k ol a o —> k spectroscopic transition is proportional to the scalar product of electric dipole (/lei) and magnetic dipole (m,rag) transition amplitudes,... 

These rotatory strengths, when combined with the reported optical purities, give [a]aba 426° and 412° for [22.10] and [26.10] betweenanenes, respectively. Since these values automatically indicate their ridiculously high [M],bs ca. 2000, the [a]D apparently are to be reduced to 1/10 th of the reported values. 

The induced magnetic dipole moment has transformation properties similar to rotations Rx, Rt, and Rz about the coordinate axes. These transformations are important in deducing the intensity of electronic transitions (selection rules) and the optical rotatory strength of electronic transitions respectively. If P and /fare the probabilities of electric and magnetic transitions respectively, then... 

The helical disposition of the aromatic ligands in the tris complexes confers optical rotatory strength on the ligand transitions [372, 495). This fact may be used to arrive at the absolute configuration of the complex, e.g., (-l-)Ru(phen) + has been shown to exist as a left-handed helix [495). The optical rotatory dispersion of phenanthroline complexes of zinc, cadmium, and mercury has also been studied [419). 

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