document: Both methods of structure solution reveal a bent conformation of the central terthiophene units of the DOTT molecule as is clearly visible in all three cases in Figure 5. However, there is a fundamental difference in the conformation of the octyl side chains. Whilst for the single crystal phase at T=100K linearly extended chains are observed (Figure 5B), a defined rotation of the octyl chains relative to the terthiophene unit is found for the three thin film phases (Figure 5A). The rotation angle of about ±70° results from a twist of the first CC single bond at the link between the terthiophene unit and the octyl chain (see arrows Figure 5A). Two features of this rotated conformation are interesting. First, a molecule with rotated side chains represents the equilibrium state of an isolated single DOTT molecule as obtained by combined MD and VASP calculations [33]. Second, the rotated conformation of the octyl chains allows a dense packing of the octyl side chains for both molecules. Interestingly, the single crystal structure at room temperature shows the twisted as well as the linear conformation of the octyl side chains within one molecule (Figure 5C).
extractive_keyphrases: bent conformation central terthiophene units combined md and vasp calculations crystal structure defined rotation of the octyl chains dense packing dott molecule linearly extended chains octyl chain octyl chains octyl side chains rotated side chains structure solution terthiophene unit thin film twist of the first cc single bond