Research

The Limburg Lab is interested broadly in supramolecular chemistry and photochemistry. Below you can find some current projects. Interested in joining us? Please send an email to Bart with a motivation letter and cv.

Photoinduced transmembrane electron transfer

Transmembrane electron transfer is a biomimetic method for the separation of electrons across a physical barrier. In nature, transmembrane electron transfer is used in photosynthesis for the production of NADPH and the oxidation of water to O₂. In our research, we are interested in producing stable charge-separation using a judiciously designed photocatalyst that bridges the membrane of a liposome. This biomimetic system has applications for the production of solar fuels (artificial photosynthesis), water-based green organic synthesis, and nanoscale systems chemistry.

Metallaphotoredox Catalysis for Organic Synthesis

Metallaphotoredox catalysis is a recently developed strategy generally employed for the construction of carbon-carbon bonds using mild catalytic conditions. Although most of the research up to now has been done using a combination of photoredox catalysis and nickel or copper catalysts, cobalt has recently shown to possess unique reactivity. Therefore, the combination of photoredox catalysis and cobalt shows great promise for the development of novel reactions. We are currently especially interested in the production of cobalt-allyl complexes and their properties in following carbon-carbon bond formation. In addition, because of the novelty of these reactions, we are interested in developing a deep understanding of the reaction mechanisms in order to make metallaphotoredox catalysis a general tool for the organic chemist.

Photocatalyst Design for Improved Quantum Yields

Photoredox reactions generally suffer from low quantum yields. This is due to the thermodynamically highly-favored recombination of charges after initial photoinduced electron transfer. In addition, photoredox catalysis in organic synthesis suffers from low chemoselectivity which hinders a scope with highly electron-rich or electron-poor functional groups due to their reactivity with the excited state of the photocatalyst. In order to meet these challenges, we design photocatalysts with supramolecular recognition groups that bind, in the ground state, to the desired reagent. As such, we prevent excited state quenching by other reagents leading to a higher chemoselectivity. In addition, by the addition of, for example, a basic moiety in the recognition group, we can force proton-coupled electron transfer, which renders the back-electron transfer unviable. As such, we prevent charge recombination, which in turn increases the quantum yield for the desired reactivity.