Enantioselective Photochromism under Circularly Polarized Light

The introduction of asymmetry into molecular systems by external chiral stimuli greatly contributes to our understanding of the intriguing homochirality which exists in biomolecules. Circularly polarized light (CPL) is a well-known chiral physical force (right- or left-handed), which can influence the enantiomeric equilibrium of racemic chiral compounds via preferential interaction with one of the enantiomers. As a light absorption moiety in the chiral system, photochromic molecules best contribute to the enhancement of spectral characteristics, which is highly desirable for the experimental observation of CPL-based enantioselective reactions. In this Minireview, CPL-directed enantioselective photochromism, with an emphasis on several azobenzene derivatives, will be discussed. We briefly discuss the recent examples of chiral amplification methods that utilize CPL chiral forces along with a short perspective for future directions.