Generation and Stabilization of Soliton‐Type Radicals in Amidine‐Linked Porous Oligoacetylene Polymers by Topological Confinement Strategy for Photothermal Catalysis

ABSTRACT Porous polymers incorporating stable organic radicals are typically limited to a handful of known radical types. Here, we introduce a topological confinement strategy that generates a previously inaccessible class of open‑shell species: neutral soliton‑type radicals, within amidine‑linked oligoacetylene networks. In chemical terms, these species are characterized by a delocalized spin density over the conjugated backbone, distinguishing them from conventional localized radicals. These materials exhibit a distinct axial g ‑tensor, Curie behavior, and broad near‑infrared absorption extending to 1000 nm. Unlike conventional photothermal systems, where heat originates from exciton transfer energy to the lattice via nonradiative processes, our system stores light energy in long‐lived soliton states that dissipate via lattice vibrations, producing no ground‑state bleach yet enabling efficient heat generation. Using this mechanism, the materials drive aldehyde‑indole coupling under mild light irradiation through a photothermal catalytic pathway. More broadly, this work translates soliton physics into a synthetic materials platform for spin‑functional materials.