Fig. 5: Spectroscopic changes during chemical CO₂ reduction/CO oxidation interconversion.

A The sequential alteration in the optical spectra of C1 in Ar-saturated DMF following gradual purging of CO₂. The inset specifically demonstrates the change in the MLCT band. B The serial changes in the optical spectra of native C1 sample under Ar atmosphere (red dotted trace) following the purging of CO₂ (blue trace), and addition of one equivalent of ascorbic acid (black trace) along with a chemically (CAN) oxidized C1 (brown trace). C The change in the EPR spectra of C1 present in Ar (red trace) following the successive addition of CO₂ (sea green trace), 0.5 equivalent (black trace) and one equivalent of ascorbic acid (violet trace). D The comparative solution state FTIR spectra of C1 under Ar (black trace) and CO₂ atmosphere (blue trace) along with a blank solution under CO₂ (red trace).