Fig. 2: Validating the redox-tunable CO₂ absorption of isoindigo.

a Bulk electrolysis of isoindigo (IId) under N₂ or CO₂ atmosphere. The CO₂ adduct can be obtained either by directly reducing IId (40 mM) in DMSO with 0.25 M LiClO₄ under CO₂ or by reducing IId under N₂ followed by purging with CO₂. b ¹H NMR and ¹³C NMR spectra of the crude solution after bulk electrolysis under CO₂. The minor isomer peaks are marked with an asterisk. c CV curves of IId (2.5 mM) in DMF using 0.1 M Nbu₄PF₆ as the supporting salt under N₂ (grey) and CO₂ (red) at a scan rate of −50 mV s⁻¹ (5 mM ferrocene as the internal reference). ∆E_peak(2) is labelled for the calculation of \({K}_{{{{{{{\rm{CO}}}}}}}_{2}}\).