Ionic Coupling-Induced Circular Dichroism ICICD

3 Ionic Coupling-Induced Circular Dichroism (ICICD) [Pg.27]

Complexes between chiral polymers having ionizable groups, and achiral small molecules become, under certain conditions, optically active for the absorption regions of the achiral small molecules. Dyes such as acridine orange and methyl orange have been used as achiral species, since they are in rapport with biopolymers through ionic coupling. This phenomenon has been applied to the detection of the helix chirality in poly-a-amino acids, polynucleotides, or polysaccharides when instrumental limitations prevent direct detection of the helices. [Pg.27]

Occasionally the ionic coupling induces conformational changes around the chiral moiety, or an achiral species becomes optically active with the ionic coupling to form a favorable conformation. These perturbations of ionic species to the optical activity of chiral species can be examined by the experimental variation of adding ionic chemical species. [Pg.27]