On-Surface\nBoronation of Porphyrin into a Molecular\nDipole

Functionalized\nporphyrins by introducing exotic atoms into their\ncentral cavities have significant applications across various fields.\nAs unique nanographenes, porphyrins functionalized with monoboron\nare intriguing, yet their synthesis remains highly challenging. Herein,\nwe present the first on-surface boronation of porphyrin, bonding a\nsingle boron atom into the porphyrin’s cavity. The boronation\nis selective, being observed exclusively in molecules featuring a\nspecific aromatic ring-fused structure (ARFS*), not the pristine porphyrin\nmolecule or its other ARFS forms. The boron’s bonding geometry\nis noncentered, transforming the boronated porphyrin into a molecular\ndipole and imparting a markedly varied electronic structure. Well-ordered\ntwo-dimensional dipole arrays are achieved. Upon elevated thermoactivation,\nintermolecular O<i>–</i>B<i>–</i>O bonds provide robustness and flexibility to the molecular chains.\nThis work demonstrates the high selectivity of on-surface porphyrin\nboronation and provides an effective strategy for tailoring molecules’\nelectronic structure, producing molecular dipoles, and promoting the\nrobustness and flexibility of molecular chains.