Chirality is a property of molecules that have a non-superimposable mirror image, also known as enantiomers. These enantiomers have the same chemical formula and connectivity but differ in the spatial arrangement of their atoms. Chirality plays a significant role in the photochemical properties of molecules, as it can affect their absorption and emission spectra, as well as their reactivity upon exposure to light.The effect of chirality on the photochemical properties of molecules can be understood in terms of the interaction between the chiral molecule and the electromagnetic radiation light . When a chiral molecule absorbs light, it undergoes electronic transitions, which can lead to the formation of excited states. These excited states can then undergo various processes, such as fluorescence, phosphorescence, or photochemical reactions.The interaction between the chiral molecule and the light depends on the polarization state of the light and the molecular structure of the chiral molecule. For example, when a chiral molecule interacts with circularly polarized light CPL , it can preferentially absorb one enantiomer over the other. This phenomenon is known as circular dichroism CD and can be used to study the chiroptical properties of molecules.The impact of chirality on the formation of enantiomers can be observed in photochemical reactions, where the product distribution can be influenced by the chirality of the reactants or the light used to initiate the reaction. One example of this is the photochemical synthesis of chiral molecules using circularly polarized light. In this case, the preferential absorption of one enantiomer by the CPL can lead to an enantioselective synthesis, where one enantiomer is formed in excess over the other.Another example is the photochemical reaction of chiral molecules with chiral reactants or catalysts. In this case, the chirality of the reactants or catalysts can influence the stereochemistry of the products, leading to the formation of specific enantiomers. For instance, the enantioselective [2+2] photocycloaddition reaction between a chiral ketone and an alkene can be achieved using a chiral sensitizer, which transfers its chirality to the excited state of the ketone, leading to the formation of a specific enantiomer of the cyclobutane product.In conclusion, chirality has a significant impact on the photochemical properties of molecules, affecting their absorption and emission spectra, as well as their reactivity upon exposure to light. This can lead to enantioselective photochemical reactions, where the chirality of the reactants, products, or light used can influence the formation of specific enantiomers.