Direct Synthesis of Semimetal Phthalocyanines on a Surface with Insights into Interfacial Properties

On-surface engineering of supramolecular structures has attracted considerable interest during the past few decades. However, organic nanostructures coordinated by group V semimetals have rarely been demonstrated. Herein, we report the metalation of a metal-free phthalocyanine (H₂Pc) via the incorporation of semimetal atoms (Sb and Bi) with insights from X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and density functional theory. While H₂Pc becomes completely metalized on the Sb(111) surface after annealing to 200 °C, the metalation of H₂Pc is only partially triggered on Bi(111) at annealing to 300 °C, and the complete metalation is done after further higher temperature annealing. Inspired by the metalation path predicted by DFT calculations, we propose that the metalation of H₂Pc on Sb and Bi semimetals is possible by the dissociation of hydrogen atoms from the pyrrolic nitrogen atom as a result of the orbital hybridization between the N-sp² state and the Bi-6p_y state, and the metalation process needs to overcome a relatively high energy barrier due to the weak mixing of atomic orbitals at discriminated energy levels. While Bi/Sb coordinated organic nanostructures have been seldom investigated before, the direct synthesis of SbPc/BiPc via on-surface reaction in this report might bring promising progress for physical chemistry and related fields.