Enantiomers are non-superimposable mirror images of each other, meaning they have the same molecular formula and connectivity but differ in the spatial arrangement of their atoms. These differences in spatial arrangement can lead to differences in their photochemical properties, which in turn can have significant implications in chemical reactions and processes.The photochemical properties of enantiomers differ mainly due to their interaction with polarized light. When plane-polarized light passes through a solution of a chiral compound, the plane of polarization is rotated either clockwise dextrorotatory or counterclockwise levorotatory . This phenomenon is known as optical activity, and the extent of rotation is determined by the compound's specific rotation. Enantiomers have opposite specific rotations, meaning one enantiomer will rotate the plane of polarized light in one direction while the other enantiomer will rotate it in the opposite direction.The differences in photochemical properties of enantiomers can have significant implications in chemical reactions and processes, particularly in the field of stereochemistry. For example, enantiomers can have different reactivity with other chiral molecules, leading to the formation of diastereomers, which have different physical and chemical properties. This is especially important in biological systems, where many molecules are chiral and can exhibit different biological activities depending on their stereochemistry.One well-known example of the implications of enantiomers' photochemical properties is the drug thalidomide. The R -enantiomer of thalidomide is a sedative and effective against morning sickness in pregnant women, while the S -enantiomer is teratogenic, causing severe birth defects. The drug was initially marketed as a racemic mixture, containing equal amounts of both enantiomers, leading to disastrous consequences.In the field of asymmetric synthesis, chemists often aim to selectively produce one enantiomer over the other, as the desired biological activity or chemical property may be associated with only one enantiomer. The differences in photochemical properties of enantiomers can be exploited in this context, using chiral catalysts or reagents that selectively react with one enantiomer over the other, or employing photochemical reactions that are sensitive to the stereochemistry of the reactants.In summary, the photochemical properties of enantiomers differ due to their interaction with polarized light, and these differences can have significant implications in chemical reactions and processes. Understanding and exploiting these differences is crucial in the development of new drugs, materials, and chemical processes with desired properties and activities.