Turning to the O 2 N(Ph) n NH 2 oligomers, we note that there is significant twisting of the (Ph) n chain in the optimized geometries that we employ, leading to a fluctuation in d rms as a function of size, which settles to an asymptotic value by n = 4 (Fig. ). For GDD tuning, that asymptotic size [d rms (ω GDD ) ≈ 2.35 Å] is nearly the same as it for the n = 1 case. For IE tuning, the asymptotic value of d rms is about 0.1 Å larger than it is in the n = 1 case and about 0.17 Å smaller than the asymptotic value of d rms (ω GDD ). These differences are much smaller than the 2.5 Å length scale of one phenyl ring and we regard them as insignificant.