PhD ceremony Ms. T. Fernández Landaluce: Molecular motors: from solution to surfaces

PhD ceremony: Ms. T. Fernández Landaluce, 12.45 uur, Academiegebouw, Broerstraat 5, Groningen

Dissertation: Molecular motors: from solution to surfaces

Promotor(s): prof. P. Rudolf, prof. B.L. Feringa

Faculty: Mathematics and Natural Sciences

Synthetic molecular motors are molecular machines capable of rotation under energy input; in the case of light-driven molecular rotors this energy input is light. Our research focused on synthetic light-driven unidirectional molecular rotary motors based on over-crowded alkenes that undergo photoisomerization followed by thermal helix inversion.

In pursuit of designing systems that can use the photo-induced rotary movement, one half of the motor is attached to the surface of a gold or silicon substrate. In such systems different orientations of the rotating part (rotor) relative to the stationary part (stator) can be envisioned. In altitudinal motors the axis of rotation is parallel to the surface, while in azimuthal it is perpendicular to the surface.

A major hurdle to apply such systems to perform complex tasks is to develop a versatile and stable method to graft them onto surfaces. “Click chemistry” reactions are expected to be a useful tool for functionalization of surfaces with rotary molecular motors. In this thesis we investigate surface attachment of altitudinal and azimuthal rotary molecular motors via click chemistry reactions. Crucially a combination of surface analysis techniques demonstrates the success of the interfacial reaction as well as the fact that the surface-bound motors preserve their light-induced rotary movement. Direct self-assembly of thiols on gold and of silanes on silicon oxide is also reported here as new routes for surface attachment of rotary molecular motors. Many synthetic routes and surface characterization techniques were explored. The in-depth analysis provides a useful guide for future surface motor assembly.