Kinetic Control of Symmetry-Broken Spin Architectures of Azafullerene on [10]Cycloparaphenylene Templates: From Frustrated 2D Lattices to Quasi-1D Chains

Abstract Supramolecular host–guest complexation provides a powerful strategy for stabilizing organic radicals and organizing them into functional spin architectures. Here, we investigate the kinetic pathways for on-surface complexation of spin-1/2 azafullerene radicals (C59N•) within templated [10]cycloparaphenylene ([10]CPP) nanohoop monolayers on Au(111), revealing a strongly anisotropic energy landscape that governs radical migration and encapsulation. Migration of isolated C59N• along the [10]CPP rims proceeds via relatively low energy barriers (∼0.45 eV), leading to preferential confinement at the nanohoop periphery prior to azafullerene encapsulation. C59N• relocation to the global energy minimum at the [10]CPP center requires overcoming substantially higher barriers of at least ∼0.8 eV, with interfullerene interactions raising these barriers further. High C59N• mobility and relaxed lateral confinement at [10]CPP template edges also activate an alternative assembly pathway in which azafullerene intercalation induces in-plane exfoliation of [10]CPP lines from the 2D [10]CPP array, creating a reconstructed two-dimensional superlattice composed of alternating zigzag chains of azafullerenes and linear rows of encapsulated C59N•⊂[10]CPP complexes. This edge-driven reorganization gives rise to anisotropic lattices of encapsulated radicals with one-dimensional structural motifs. The control over the rich energy landscape of C59N•⊂[10]CPP complexation thus enables access not only to geometrically frustrated two-dimensional lattices but also to quasi-one-dimensional chain motifs of spin-1/2 carrying radicals within a single supramolecular platform.