High precision analysis of conformational and electronic structures of organic molecules by CD and MCD spectroscopy

Abstract

The utility of circular dichroism (CD) and magnetic circular dichroism (MCD) is presented with typical examples. Thus, conformation of natural ortho-diols is determined by modifying the diols by macrocyclic compounds and by analyzing their CD spectra. The sign of the CD spectra is confirmed to be plus in the left-handed circumstances, while minus in the right-handed circumstances. The helix sense of artificial β-polypeptides is determined by the theoretical analysis of their CD spectra. The chirality of a system comprising of two porphyrins and a chiral amine is determined by the analysis of its CD and MCD spectra. The assignments of electronic absorption bands of porphyrinic sandwich compounds are unambiguously determined in consideration of MCD theory. In almost all these cases, the spectra are interpreted based on the concept of CD and MCD theory, and in some cases, molecular orbital calculations lend support to the results.