Persulfurated Benzene‐Cored Asterisks with π‐Extended ThioNaphthyl Arms: Synthesis, Structural, Photophysical and Covalent Dynamic Properties

The synthesis of regioisomeric asterisks (5) and (6) incorporating a benzene core with six 1‐naphthylthio or six 2‐naphthylthio arms are reported in search for new materials with optoelectronic properties. The consequences on the extension of a π system surrounding a persulfurated benzene core provide a new avenue to study the structural, photophysical, and chemical properties of such family of all‐organic phosphors. It also diverts the persulfuration mechanism after two radical cyclizations for making a [5]dithiohelicene by‐product (7) and favors dynamic sulfur component exchange reactions surrounding the core. These exchanges convert asterisks (5) and (6), non‐phosphorescent at 20 °C to the highly phosphorescent (4) (ϕ ∼100 %, solid state at 20 °C). For asterisks (5) and (6), the absence of the typical phosphorescence of the per(phenylthio)benzene core in the solid state at 20 °C and the presence of a weak naphthalene‐based phosphorescence at 77 K is attributed to an energy transfer from the triplet state of the persulfurated benzene core to the outer naphthalene moieties, resulting in an antenna system.