We produce guidelines for the design and construction of more efficient molecular motors and explore how molecular motors can be used to power nanodevices for molecular transport. Molecular motors are molecules that perform work by absorbing energy and converting the energy into directed mechanical motion such as rotation around a chemical bond. To fully exploit the nanotechnological potential of these motors, it is imperative to design and synthesize systems capable of achieving high (>MHz) rotational frequencies under ambient conditions both in solution and when incorporated into a nanodevice. Using a variety of computational techniques, ranging from quantum chemical calculations to excited-state molecular dynamics simulations, our research in this field aims to provide an atomic- and electronic-level understanding of how this goal can be realized.
Photochemical reaction mechanisms
We investigate the mechanisms of organic and biochemical photoreactions. Whereas ordinary thermal reactions are induced by heat and involve exclusively ground-state species, photoreactions are triggered by light and involve species that during parts of the reaction reside in an excited state. In our research, we explore the mechanistic details of photoreactions by calculating the relevant ground- and excited-state potential energy surfaces with quantum chemical and QM/MM methods and by running non-adiabatic molecular dynamics simulations.
We study the basic functions of photosensory proteins and explore their potential as bioimaging tools with new areas of application. Photosensory proteins are widespread signal transduction proteins that employ chromophores to detect light and initiate a physiological response to the prevailing light conditions. One family of proteins of particular interest are the bilin-chromophore-containing phytochromes, which are responsive to red and far-red light. Our QM/MM-based research on these proteins has two key objectives. The first is to understand how light absorption by the bilin chromophore activates phytochromes. The second is to design new engineered phytochrome variants that show strong fluorescence in the near-infrared window between 650 and 900 nm. Such proteins are ideal for bioimaging applications in cancer diagnostics.
We investigate how spectroscopic properties of organic and inorganic chromophores confer functionality to the chemical systems where they are present. The functionalities of interest range from color to proton transfer capability and catalytic power. As an example of this research, we have recently succeeded in explaining one of the most curious coloration phenomena in Nature, whereby lobsters attain their characteristic deep-blue color from the binding of a distinctly orange-red carotenoid pigment in a protein complex present in their shell. This work, done in collaboration with experimentalists, also helps explain why lobsters change color from deep-blue to orange-red when cooked!