Modern Electroanalytical Methods to Study Organic Compounds, Materials, and Reactions. Jadwiga Frelek, Marcela Geiger and Wolfgang Voelter.
Circular dichroism is obtained only within absorption bands.
Carbohydrates, but also alcohols, amines, ethers etc. are transparent in the UV-VIS region of commercially CD spectropolarimeters. In order to see Cotton effects of such compounds, new chromophors have to be introduced in their molecules to form so-called cottonogenic derivatives. One procedure for this is the in situ formation of chiral complexes by mixing the optically active but non-absorbing substance with a solution of an achiral transition metal complex. By examination of the CD bands of these chiral complexes, configurational and conformational features of the ligands can be determined. They exibit, depending on the sugar structure, two kinds of typical CD curves, whose parameters are correlated, according to a chirality rule, with the sugar configurations.