Sequential oxidation of sulfur annulated perylenediimide: an efficient strategy to generate ultra-stable radical anions and dianions

Sulfur annulated PDI (SAN-PDI) has been oxidized to three sequential levels (from sulfide/disulfide to sulfoxide/sulfone) using meta-chloroperoxybenzoic acid (mCPBA) to achieve electron-deficient PDI derivatives (1, 2, and 3). Each oxidation level leads to a shift towards a more positive reduction potential and thus increases the electron affinity. These PDI derivatives 1, 2, and 3 have been employed as precursors for the efficient generation of radical anions and dianions. The radical anion formation has been investigated using UV-Vis-NIR absorption and validated with EPR spectroscopy. The generated reduced species were found to be exceptionally stable (t_1/2 > 5 years) under ambient conditions. The compound 3 shows radical anion generation in a solid-state thin-film upon exposure to amine vapors. Furthermore, the oxidized products have been optimized using DFT calculations to obtain their physiochemical properties. Hence, the extraordinary stability of radical anions and dianions of oxidized SAN-PDI under ambient conditions will make them a potential candidate for molecular magnetism, catalysis, and photovoltaics applications.