Principles and Applications of CD Spectroscopy

Abstract

Chiral molecules exhibit different absorbance for left and right circularly polarized light. This phenomenon is called circular dichroism (CD). To measure CD spectra, a CD spectrometer alternately irradiates a sample with left and right circularly polarized light, and detects the difference in absorbance between the two cases.

CD spectroscopy is more sensitive and easier to perform than NMR or X-ray crystallography, and sample conditions such as the temperature and pH can be changed easily. Therefore, CD spectroscopy is suitable for measuring structural changes in chiral molecules while varying the sample environment. Because of the wide wavelength range from the far ultraviolet to the near infrared, biomolecules such as proteins, organic compounds and metal complexes can be targeted.