In the past decade a series of useful molecular systems known as phototriggers, photoswitches, photocaging groups, or photoremovable protecting groups (PRPGs) have been used in a wide variety of applications, including the release of fragrances from household goods, as an aid in multi-step synthesis, and in drug and gene delivery. PRPGs also make it possible for biochemists to release bioactive compounds in living tissue with both high temporal and spatial accuracy, thus making it possible to study physiological events such as enzyme activity, ion channel permeability, and muscle contraction by ATP hydrolysis. The choice of PRPG is critical, depends on the system under investigation, and must be tailored to the application. Thus, there is a need for new PRPGs that can satisfy the diverse requirements of numerous applications.
We have designed several new photoprotecting groups and studied the mechanism for the photorelease. Understanding the reaction mechanism for the photorelease has allowed us to design the next generation of PRPGs that can be tailored towards specific applications.
We have designed PRPGs that use photoenolization to initiate release of alcohols. These systems release their alcohols moiety independent of the reaction medium and can take place in thin films in the presence of oxygen and are therefore excellent to release fragrance in house-goods. (For more details click on these links 1 and 2)
Currently, we are using radicals and radical rearrangement along with intramolecular H-atom bonding to achieve photorelease in high quantum yields and to control the rate of release.