The role of radical-π dispersion interactions in visible-light promoted sequences and radical polymerizations

In the last decades, the use of photocatalysis has allowed the access to uncommon reaction pathways for the synthesis of highly functionalized and architectural complex molecular scaffolds. The field of radical chemistry has benefited from the introduction of Ruthenium and Iridium based photocatalysts. However, these protocols have to deal with the low concentration of these highly reactive species. Therefore, different strategies based on the introduction of additional catalytic cycles have been developed. Organocatalysis, acid-base interaction and transition metal catalysis have addressed these difficulties. Unfortunately, many of these protocols suffers from limited generality. Here we propose a new approach based on the introduction of dispersion interactions to promote EnT based processes that involve the formation of open-shell (bi)radical intermediates. Particularly, the approach was developed starting with additives that are helpful for the target reaction when they are present in sovrastechiometric amount. Then we developed a series of tailor made co-catalysts and decorated photosensitizers that allowed us to achieve similar results employing catalytic loadings. A similar strategy was implemented in a novel co-initiator system for the radical polymerization of the acrylates. The results here reported allows the successful implementation of new general strategies to improve the efficiency of energy transfer methods and free-radical polymerization protocols.