Introduction to Photochemistry for the Synthetic Chemist

The concerns raised by the pollution connected with chemical processes have recently pushed chemists to (re)consider alternative approaches, until now limited to academic studies. Thus, different strategies have been proposed to surmount this problem, and photochemistry, which studies the use of light to promote a chemical conversion, is widely considered as one of the best choices. It is commonsense that the nature and the energy distribution of the molecular orbitals dictates the chemical behavior of a given compound under thermal conditions. Photochemistry strongly emerged also as a tool for the photogeneration of reactive ground-state intermediates. A crucial issue in the design of a photochemical reaction is assuring an efficient light absorption of the photoreacting species. The use of intense light sources (including solar light) may raise some safety issues. Photocatalysis has recently revolutionized the approach to organic synthesis through radical and radical ion intermediates.