Strain-Enabled Redox Chemistry of Naphthalene Peri-Dichalcogenides: Synthetic Strategies, Unusual Reactivity,...

Naphthalene peri-dichalcogenides featuring sulfur, selenium, or tellurium at the 1,8-positions constitute a privileged platform where enforced proximity of two heavy chalcogen centers raises donor ability, introduces strain, and enables through-bond/through-space communication. In this Review, we critically explore how these structural constraints give rise to a range of unusual reactivity patterns including rapid two- and multi-electron redox processes and proton-coupled electron-transfer pathways that can trigger self-redox behavior. Stepwise oxidation often leads to the formation of persistent radical cations, particularly in sulfur and selenium systems. In contrast, tellurium derivatives frequently access thermally robust dications, whose stability is enhanced by secondary or hypervalent interactions. We summarize the synthetic approaches used to access both open peri-dichalcogenides substituent pairs and bridged naphtho[cd]dichalcogenoles, including peri-directed metalation followed by elemental chalcogen transfer, stepwise substitution of peri-dihalo aromatics, and oxidative coupling routes. Particular emphasis is placed on substituent patterns, such as 2,7-donor groups, that effectively modulate solubility and HOMO energy levels. Mechanistic sections discuss electronic factors (HOMO elevation, polarizability), strain release, and orbital interactions (chalcogen-π and E•••E interactions) that rationalize chalcogen-dependent chemoselectivity and rate enhancements. Applications include biomimetic catalysis, such as glutathione peroxidase (GPx) activity and iodothyronine deiodination mimics, as well as selective reductions of nitro and azide substrates, charge-transfer (CT) materials, and redox-switchable donors, and ROS-responsive sensing motifs. We conclude with design principles for harnessing peri-geometry-tuning PCET via acidity, exploring hypervalent Te chemistry, and developing water-compatible or solid-state architectures-and highlight opportunities in catalysis, energy storage, and functional materials where these compact, conformationally locked chalcogen frameworks surpass conventional organochalcogen system.