Exciton coupling analysis and enolization monitoring by vibrational circular dichroism spectra of camphor diketones.

The keto-enol tautomerization of (1R,3R,4R)-(+)-3-benzoylcamphor in solution was traced by the infrared (IR) and vibrational circular dichroism (VCD) spectra, reflecting the Boltzmann populations of the isomers. To investigate the exciton coupling of the carbonyl vibrations in the region 1800-1600 cm(-1), VCD spectra of a series of camphor derived β-diketones were analyzed with the support of density functional theory (DFT) calculations. The results confirm the importance of the exciton chirality for VCD and manifest that the VCD spectroscopy is a convenient technique to investigate the keto-enol tautomerization equilibria in chiral diketones.