Overcrowded alkene-based molecular motors: from single molecule to multimotor systems

PhD ceremony: Mr. A. Cnossen, 12.45 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Overcrowded alkene-based molecular motors: from single molecule to multimotor systems

Promotor(s): prof. B.L. Feringa

Faculty: Mathematics and Natural Sciences

The research is focused on increasing the understanding of the mechanism of rotation of light-driven second generation molecular motors with the ultimate goal of applying them in nanotechnology.

In the first experimental chapter the thermal step of the rotation is studied using quantummechanical calculations and spectroscopy. This revealed the conformational changes during the thermal step. Next, the photochemical step was studied at the sub-picosecond timescale. Further studies are needed to fully clarify the motions during the photochemical step.

In the second part of the thesis ways in which the rotation of molecular motors might be applied in nanotechnology are investigated. First, a way to power these motors using visible light rather than UV light was developed. This could be a first step towards their application in biological systems. Second, ordered monolayers of molecular motors on graphite could be made. This order could prove crucial in taking advantage of the motions of a large number of motors, however, rotation of the motors in the monolayers could not be demonstrated. Finally, molecular motors were incorporated in polymers. It was demonstrated that the rotation of the motors is retained while attached to the polymer. Moreover, isomerization of the motor was shown to influence the conformation of the polymer chain.

Ten eerste heeft het onderzoek een belangrijke bijdrage geleverd aan het begrip van hoe de rotatie in tweede generatie moleculaire motoren tot stand komt. De thermische stap wordt nu goed begrepen, maar voor de fotochemische stap zijn nog meer experimenten nodig. Ten tweede zijn er stappen gemaakt naar manieren om deze moleculaire motoren toe te passen in de nanotechnologie; er werd een systeem ontwikkeld dat wordt aangedreven door zichtbaar licht, er kunnen geordende monolagen worden gemaakt en er kan gebruik worden gemaakt van polymere systemen.