The chemist Dr. Henry Dube develops tiny machines at molecular level that can be controlled with light. His Emmy Noether junior research group uses the molecule hemithioindigo as a basis. In collaboration with Eberhard Riedle, Professor of Experimental Physics at the Department of BioMolecular Optics, and Regina de Vivie-Riedle, Professor of Theoretical Chemistry at the LMU, he has now been able to fully elucidate the mechanism of light-driven rotation within SFB 749. The research team is currently reporting on the results in the journal JACS.
Hemithioindigo has a carbon double bond. When light is applied, the molecule changes its structure and rotates around its double bond. As Dube has already been able to show in previous work, a complex engine based on Hemithioindigo can be built and very well controlled. In addition, it requires less energy-rich light than most other molecular motors, which increases its potential applications and makes it particularly interesting for biological and medical purposes.
The cooperation enabled them to decode the complex mechanism of rotation by means of ultrafast motion analysis using short-time spectroscopy and quantum mechanical calculations of the possible reaction pathways. Among other things, it can be shown that the rotation is unidirectional even at room temperature and how the speed of rotation can be influenced particularly effectively. The speed and probability of the four steps, which give the complete rotation, was thus clarified for the first time. The time scales relevant for the rotation range from picoseconds (10-12s) to milliseconds (10-3s) and were thus observed spectroscopically over more than nine orders of magnitude in time. "Our work gives an unprecedented insight into how molecular motors work. Thanks to the analysis, we now have a complete picture of the rotational movement and can then build on new approaches to design engines that are even more powerful, " Henry Dube says.
Roland Wilcken u.a.: „Complete Mechanism of Hemithioindigo Motor Rotation“, In: JACS 2018