The sunny side of chemistry: green synthesis by solar light.

The storage of solar energy is one of the main challenges in the near future. A rather unexploited way to fulfil this goal is the solar light induced formation of new chemical bonds, i.e. the synthesis of chemicals. Solar photons can be considered the ideal green reagents since they are costless and leave no residue in the reaction mixture. In many cases the solar radiation could be successfully used in place of toxic or expensive chemical reagents to overcome the activation energy in organic synthesis. In this perspective, the emerging trends on the use of solar light for green synthesis are summarized, highlighting the advantages of this photochemical method.