Fig. 4. Structural and spectral comparison of the most stable conformation of (R_mp)-2Ac and the two most stable conformations, A and B, of (R_mp)-2Ac²⁺. Oxidation induces a flip of the naphthalene moiety in A towards the TTF unit yielding conformation B. The difference in electronic energy between A and B is around 9 kJ mol^–1. All structures were obtained at the TPSS-D3(BJ) level. Corresponding simulated CD spectra with excited state difference densities of selected transitions (insets) visualising the change in electronic structure upon photoexcitation of (R_mp)-2Ac (left) and (R_mp)-2Ac²⁺ (middle). The difference in the CD spectra due to the conformational change of (R_mp)-2Ac²⁺ is negligible in the region of interest. The spectra were obtained at the ωB97X-D3 level using sTD-DFT. Gaussian line broadening with σ = 20 nm was applied. Insets: blue and red zones correspond to areas of electron enhancement and electron depletion, respectively. Isovalue = 0.001 a₀^–3.