On-surface synthesis and interfacial charge redistribution of open-shell [3]triangulene-fused porphyrins on Au(111)

The on-surface synthesis of porphyrin-nanographene (Por-NG) hybrids enables systematic control of π-electron magnetism in organic materials, yet the spin behavior of these systems remains difficult to predict because the porphyrin core perturbs the graphene lattice. We report the fabrication and electronic characterization of ZnPors fused with two and four [3]triangulene units (i.e. ZnPorT₂ and ZnPorT₄ , respectively) on Au(111). Rapid thermal annealing maximizes the yield of discrete hybrids by suppressing surface diffusion and unwanted lateral fusion. Scanning tunneling microscopy and spectroscopy, supported by theory, show that both ZnPorT₂ and ZnPorT₄ exhibit diradical character with an antiferromagnetically coupled ground state. The hybrids undergo interfacial charge transfer to the metallic substrate: ZnPorT₂ donates one electron, forming open-shell ZnPorT₂ ^{• +} , while ZnPorT₄ donates two electrons, affording closed-shell ZnPorT₄ ²⁺ . Despite this charge transfer, the multireference character of the frontier orbitals remains in ZnPorT₂ ^{• +} . The results establish an efficient route to complex Por-NG hybrids and clarify how molecular design and interfacial charge transfer shape their magnetic properties, an essential step toward functional magnetic nanoarchitectures.