Figure 2.

(a) Cyclic voltammograms of 1–4 measured in CH₂Cl₂ solution (1.0 × 10⁻³ mol·L⁻¹) with 0.1 mol·L⁻¹ Bu₄NPF₆ at a scan rate of 100 mV·s⁻¹; (b) HOMO and LUMO energy levels of these compounds.