Taken together, this behavior establishes a continuous four-step cycle of isomer interconversions under continued illumination in apolar solvents. The cycle proceeds via an initial double bond photoisomerization from CT-1 to DT-1 followed by a thermal atropisomerization ratcheting step from DT-1 to DR-1, photoisomerization from DR-1 to CR-1, and a final thermal atropisomerization from CR-1 to CT-1. It needs to be emphasized here that the two thermal atropisomerization steps are proceeding with significantly different efficiencies. While DT-1 to DR-1 conversion is quantitative, the conversion from CR-1 to CT-1 strongly depends on the relative energies of these two states, which can be switched upside down by choice of the solvent (Figure ). Therefore, a proficient four-step cycle is present in apolar solvents such as CS2, whereas in polar solvents like CD2Cl2 the dominating process is simple photoswitching between CR-1 and DR-1. A related toggling between switch and motor function reported earlier required much more drastic chemical changes, i.e. acid base additions to a dedicated basic site of the motor. Isomer AR-1 was not found to be populated under any illumination conditions, which also excludes a light-induced 360° rotation around the central double bond in machine 1 (see the Supporting Information chapter 6.1). When considering the four-step isomer interconversion under illumination in apolar solvents and the associated structural changes, a distinct type of rotary molecular motor behavior is established for 1 (Figure ). However, in this molecular motor directional circular rotation is not proceeding around a specific covalent bond axis. Instead, the PEG-linker chain moves directionally around a shifted virtual axis. To visualize this directional movement, we chose a single marker point on the PEG-chain that can be followed in its position with respect to the fixed thioindigo fragment during operation of motor 1. In the initial CT-1 state, the ethylene glycol chain connecting the indanone rotor to the biaryl unit, reaches from one half-space of the thioindigo plane to the other, thus adopting a S-shape conformation. This positions the chosen marker point on the PEG-linker at the upper right area (position 1) for the chosen perspective in Figure . Visible light induced photoisomerization to DT-1 is accompanied by severe stretching of the S-shaped PEG-linker, which is also evident from the theoretically obtained geometry. Now the marker point on the PEG-linker resides in the upper left position (position 2 in Figure ). Upon thermal atropisomerization from DT-1 to DR-1 the attachment points of the PEG-linker chain reside in the same half-space of the thioindigo plane leading to a relaxed structure. Consequently, the marker point on the linker now resides in the lower left position (position 3 in Figure ). This atropisomerization represents a thermal ratcheting step enabling the motor to continue directional rotation by entering a second separate photoequilibrium. Isomer DR-1 thus photoisomerizes into CR-1, which compresses the PEG-linker chain and shifts the marker point in the lower right position (position 4 in Figure ).