Competitive Metal Coordination of Hexaaminotriphenylene on Cu(111) by Intrinsic Copper Versus Extrinsic Nickel Adatoms

Abstract

The interplay between the self‐assembly and surface chemistry of 2,3,6,7,10,11‐hexaaminotriphenylene (HATP) on Cu(111) was complementarily studied by high‐resolution scanning tunneling microscopy (STM) and X‐ray photoelectron spectroscopy (XPS) under ultra‐high vacuum conditions. To shed light on the competitive metal coordination, comparative experiments were carried out on pristine and nickel‐covered Cu(111). Directly after room‐temperature deposition of HATP onto pristine Cu(111), self‐assembled aggregates were observed by STM, and XPS results indicated still protonated amino groups. Annealing up to 200 °C activated the progressive single deprotonation of all amino groups as indicated by chemical shifts of both the N 1s and C 1s core levels in the XP spectra. This enabled the formation of topologically diverse π–d conjugated coordination networks with intrinsic copper adatoms. The basic motif of these networks was a metal–organic trimer, in which three HATP molecules were coordinated by Cu3 clusters, as corroborated by the accompanying density functional theory (DFT) simulations. Additional deposition of more reactive nickel atoms resulted in both chemical and structural changes with deprotonation and formation of bis(diimino)–Ni bonded networks already at room temperature. Even though fused hexagonal metal‐coordinated pores were observed, extended honeycomb networks remained elusive, as tentatively explained by the restricted reversibility of these metal–organic bonds.

Two-dimensional conjugated metal–organic frameworks (2D c-MOFs): chemistry and function for MOFtronics

“…In addition to wet-surface, the on-surface synthesis using Cu (111) or Au(111) substrates under ultrahigh vacuum provides another pathway to develop a single-layer 2D c-MOF that guarantees a molecular structural resolution with the support of a scanning tunneling microscope (STM). [162][163][164][165] 165 Despite the preliminary success of the on-surface synthesis, many synthetic challenges remain to be addressed, such as the synthesis of large-area (from mm 2 to cm 2 ), highly-ordered monolayer networks, the complete lift of the monolayer from the solid surface for device integration, and so on.…”

On-surface isostructural transformation from a hydrogen-bonded network to a coordination network for tuning the pore size and guest recognition

“…The protons on the ligands may be replaced by metal atoms (protons were reduced by metal atoms to hydrogen), but the connection modes between hydrogen-bonding and coordination-bonding are generally different, making it difficult to predict 2D structures before and aer transformation. 28,[32][33][34] The linear coordination mode of monovalent coinage metal ions resembles those of strong hydrogen bonds, which has been well demonstrated in metal imidazolate frameworks. [35][36][37] However, surface-supported coordination networks based on imidazole derivatives have not been reported, probably because imidazole derivatives and their metal complexes can seldom form planar supramolecular structures.…”

Two-Dimensional Carbon-Rich Conjugated Frameworks for Electrochemical Energy Applications

“…In this context, the topological structures of the constructed 2D c -MOFs can be feasibly tailored by ligand design, resulting in different pore geometries (e.g., triangle, square, and hexagonal) and pore sizes (from non-porous to 2 nm in diameter). A variety of methods have been utilized to synthesize 2D c -MOFs, such as solvo­thermal synthesis, , interface-assisted synthesis, , on-surface synthesis, and surfactant-assisted synthesis, which produce 2D c -MOFs with various morphologies, such as bulk crystals, ultrathin nanosheets (<5 nm), and single-/few-layer films.…”