Photochromic Control of Energy Transfer Using DNA as a Template

Research Project, 2013 – 2016

In this project, light will be used as the external stimuli to reversibly control the flow of excitation energy along various self-assembled DNA constructs. The key players will be photochromic molecules, also known as photochromes, incorporated into the DNA constructs. The pronounced changes in excitation energies that follow upon isomerization between the two isomeric forms of a photochrome, which manifests itself in absorption and emission changes, will be used to switch the electronic communication between the photochrome and other surrounding molecules in the DNA constructs. This will in turn affect the energy transfer process. In addition to the spectral changes, the photochromes are also experiencing structural changes upon isomerization. These changes will be used to make or break supramolecular DNA complexes, which allows for energy transfer switching by light-induced structural modifications. In addition to trivial on-off switching of the energy transfer process, directional double-throw switching could also be achieved where the excitation energy transfer is directed down either one of two branches. Fractional isomerization of the photochromes will be used for dichromatic and trichromatic emission color tuning as well as white light generation. Due to the all-photonic nature of the external stimuli, the switching occurs in a waste-free and totally reversible fashion, as opposed to many other systems that rely on the addition of chemical species.