Circular dichroism of molecules requiring two substituents for chirality

A perturber that lies on a reflection plane of a chromophore gives no net helical character to transitions of that chromophore, and hence no circular dichroism spectrum. If, however, a molecule has two such substituents then it may in fact be chiral, with its circular dichroism resulting from the concerted coupling of both substituents to the transition of interest. In this paper the circular dichroism spectra of olefin and carbonyl molecules of this kind are analysed and related to the molecular geometry using an extended independent systems perturbation approach.