Modification of graphite surfaces for the adsorption of molecular motors

The molecular motors developed in the group of professor Ben Feringa are based on overcrowded alkenes. These molecules can rotate unidirectionally upon irradiation with light. However, it is difficult to make use of this rotation because their motion in solution is overwhelmed by random Brownian motion. However, it is possible to use the rotation of the motors to induce translational movement by placing them on a surface.

Various chemists and physicists have already succeeded in placing molecular motors and nano-machines on surfaces. However, this has required an ultra-high vacuum environment and often very low temperatures. Operating and investigating nano-machines under ambient conditions would be a major advance. In this way, expensive ultra-high vacuum equipment would no longer be necessary and many of the experimental parameters could then be adjusted more readily, which would accelerate new developments in this research area. The disadvantage of working under ambient conditions is the high speed of the molecules’ intrinsic motion, which makes the study of molecular motors more difficult.

This thesis describes new strategies for the adsorption and immobilization of molecular motors on graphite under ambient conditions. The different systems have been studied with a scanning tunneling microscope (STM). One of these strategies is to use an adlayer, an extra layer of adsorbed molecules (isophthalic acid) on the graphite surface, to bind the molecular motors. Another successful method is the incorporation of the motors in molecular tapes, which allows very precise arrangement of the motors on the surface.