AmericanChemicalSociety.com

In the past decade phototriggers, 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 syntheses, and in drug delivery. PRPGs have also made it possible to release bioactive compounds in living tissue with both high temporal and spatial accuracy, therefore making it practical to study physiological events such as ion channel permeability and muscle contraction by ATP hydrolysis. The choice of PRPG is critical, depending 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 PRPG’s, which are benzophenone and acetophenone derivatives. With the aid of, transient spectroscopy, density functional theory calculations and product studies, we were able to elucidate the mechanism for the release of alcohols from these PRPGs. The release of the alcohol moiety is initiated by intramolecular H-atom abstraction. Both the rate and quantum yield for the photorelease can be controlled by intramolecular H-atom bonding. Furthermore, intramolecular H-atom abstraction to form radicals that undergo irreversible rearrangements can also be used to ensure high quantum yields for photorelease. Designing novel PRPGs and studying the mechanism for the photorelease has added a new dimension to the research focus of the PI, allowing her to gain new technical knowledge and to embark upon more challenging research projects. The graduate students that carried out the research obtained training in doing independent research and in turn they trained several undergraduate and high school students to do research. Thus, making all the students involved better prepared for future employment as scientists.