ESR measurements were carried out on a polymer bulk sample with vapor phase iodine doping. Figure 6 shows ESR spectra of (–)-poly1 with in-situ doping for 0–50 min. The ESR signal indicates that radical cations were generated along the polymer main chain. The generation of radical cations can enhance electrical conductivity of the polymer [25]. g-Value, intensity, and peak-width plots vs. the doping time of (–)-poly1 are shown in Figure 6b,c.