Fig. 5: Redox state identification of pyrazinacenes 1 and 2 in the solution phase.

a UV/Vis (solid lines) and fluorescence emission spectra (dashed lines) of 1 and 2 in dry CH₂Cl₂. Insets show photographs of solutions under room light and 365 nm ultraviolet light. b UV/Vis (solid lines) and fluorescence emission spectra (dashed lines) of 1-ox and 2-ox prepared by respective treatment of 1 and 2 with PbO₂ in CH₂Cl₂. Insets show photographs of the respective solutions under room light. c Spectroelectrochemistry of (left) 2 and (right) 1 in benzonitrile with applied positive potential of 1.0 V. Insets of c show the respective differential pulsed voltammograms. d Thermally induced oxidation in air: variation in solid state UV/Vis spectrum of 1 prior to (orange line) and following (blue line) heating in air at 370 °C. Insets show photographs of the corresponding solid states. e Photoreduction of 1-ox in CH₂Cl₂ promoted by irradiation from a Hg/Xe lamp; the UV/Vis spectrum of the reduced state of 1 is re-emerging. Blue arrows denote the decreasing intensity of the peaks corresponding to the oxidized form 1-ox, orange arrows denote the emerging intensity of the peak associated with the native form, 1.