We also perfomed an unrestricted DFT (B3LYP/6-311G++(2df,2pd)) relaxed scan on the S0 potential energy surface by rotating around the double bond and, employing a broken symmetry methodology, found a barrier between 1a and 1b with height 2.0 eV, which is substantially higher than that found in the neutral fluorene based molecular motor (1.4 eV).26 The increase in relative energy of conformer 1b compared to 1a and increased barrier height could be attributed to the increased bulk of the rotor and the COO– substituent on the stator of our molecular motor, but it is worth noting that we only performed a single relaxed scan because we used a large basis set, rather than a multidimensional relaxed scan. We also performed a DFT (B3LYP/6-311G++(2df,2pd)) relaxed scan rotating around the double bond from conformer 1b to 1c and found a low (0.2 eV) barrier, which is consistent with this step being a thermal process on the ground electronic state.