Design, Synthesis, and Isomerization Studies of Light-Driven Molecular Motors for Single Molecular Imaging

The design of a multicomponent system that aims at the direct visualization of a synthetic rotary motor at the single molecule level on surfaces is presented. The synthesis of two functional motors enabling photochemical rotation and fluorescent detection is described. The light-driven molecular motor is found to operate in the presence of a fluorescent tag if a rigid long rod (32 Å) is installed between both photoactive moieties. The photochemical isomerization and subsequent thermal helix inversion steps are confirmed by ¹H NMR and UV-vis absorption spectroscopies. In addition, the tetra-acid functioned motor can be successfully grafted onto amine-coated quartz and it is shown that the light responsive rotary motion on surfaces is preserved.