UV–Vis and ECD spectroelectrochemistry of atropisomeric naphthalenediimide derivative

The UV–vis and ECD spectroelectrochemistry (SEC) of a chiral binaphthalenylamine derivative of the N-butyl naphthalenediimide (NDIB-NH2) enantiomers were applied to measure UV–vis and ECD spectra of NDIB-NH2 radicals and dianion formed in the reduction and oxidation processes observed in cyclic voltammetry (CV). The CV curves and EPR spectroelectrochemistry enabled us to establish conditions at which a radical-anion [NDIB-NH2]̇.−, a dianion [NDIB-NH2]2−, and a radical-cation [NDIB-NH2]̇.+ are formed. The UV–vis spectra of radical-anion and dianion show the most significant changes in the 400–800 nm range. For the first time, an isosbestic point (455 nm) was found in ECD spectroelectrochemical measurements for the radical-cation [NDIB-NH2]̇.+ in equilibrium with the NDIB-NH2 neutral form. The TD-DFT CAM-B3LYP-D3/6-31G** calculations combined with the hybrid (explicit combined with implicit) solvation model fairly well reproduced the UV–vis and ECD SEC of neutral and redox forms of NDIB-NH2 but the ECD spectrum of [NDIB-NH2]̇.+ above 390 nm.