Self-Assembled 2D-Coordination Kagome, Quadratic, and Close-Packed Hexagonal Lattices Formed from a Cyano-Functionalized Benzoporphyrin on Cu(111)

Abstract

We investigated the adsorption of 2H-5,10,15,20-tetracyanophenyl-tetrabenzoporphyrin (2H-TCNPTBP) molecules on Cu(111) by scanning tunneling microscopy in ultrahigh vacuum at room temperature. Three types of network structures are observed to coexist on the surface. The first two, a porous Kagome lattice and a porous quadratic structure, are stabilized by cyano–Cu–cyano bonds with Cu adatoms; the third is a close-packed hexagonal network, with much weaker intermolecular H-bonds and dipole–dipole interactions of oppositely oriented cyano end groups. The coexistence of the three structures is attributed to very similar energetics. While the two metal-coordinated porous structures with identical molecular density are stabilized by the energy gain due to the network formation, the hexagonal network compensates the weaker intermolecular interactions by a factor of 2.3 higher molecular density; furthermore, kinetic stabilization might play a role. Our results show that cyano functionalization of benzoporphyrins gives rise to unusual two-dimensional self-assembled lattice structures.

Structure and Conformation of Individual Molecules upon Adsorption of a Mixture of Benzoporphyrins on Ag(111), Cu(111), and Cu(110) Surfaces

“…We observed only a disordered phase. We tentatively assign our observations to a dehydrogenation process within the porphyrin yielding the formation of new intramolecular C−C bonds between the isoindole and the phenyl groups (see refs [20b,29,31] . and references therein).…”

“…The outer four protrusions, that is, those at the edges of the rectangle always appear dim. By comparison with the chemical structure in Figure 1 and STM reports concerning different porphyrins in literature (see ref [20a,b,25a,27b] . and references therein), we assign them to the peripheral phenyl substituents.…”

“…Benzoporphyrins have a variety of potential practical applications, such as organic near‐infrared devices, [15] oxygen sensors, [16] photodynamic therapy, [17] organic thin‐film transistors, [18] and dye‐sensitized solar cells [14,19] . Despite this relevance, only very few investigations of their adsorption behavior on different metal surfaces have been reported to date: [20] For 2H‐5,10,15,20‐tetrakis‐(2‐naphthyl)‐benzoporphyrin (2H‐TNBP) on Cu(111), individual molecules were observed, whereas islands with square arrangements were observed on Ag(111); [20a] for 2H‐5,10,15,20‐tetrakis(4‐cyanophenyl)‐tetrabenzoporphyrin (2H‐TCNPTBP), Kagome, quadratic lattice, and hexagonal networks coexist on Cu(111); [20b] for 2H‐5,10,15,20‐tetraphenyltetrabenzoporphyrin (2H‐TPTBP), 2D islands with the molecules arranged in a herringbone structure are found on Cu(111) and Ag(111), whereas on Cu(110) 1D molecular chains were observed; [20c] for Ni(II)‐5, 10, 15, 20‐tetraphenyltetrabenzoporphyrin (Ni‐TPBP), oblique, herringbone, and cross structures coexist on Cu(111); [20d] and finally for Ni(II)‐meso‐tetrakis(4‐ tert ‐butylphenyl)‐benzoporphyrin (Ni‐TTBPBP), islands with square arrangement were observed on Cu(111) [20e] . Such arrangements could find potential applications in organic electronics or catalysis.…”

On-surface synthesis of ethers through dehydrative coupling of hydroxymethyl substituents

“…Notably, all of the molecules in the network are connected through a uniform structural motif with both of their hydroxymethyl termini interacting with two molecules. The long-range organization and the uniform structural motif point to intermolecular supramolecular interactions, [37][38][39] which arise from the hydroxymethyl substituents. To further identify its atomic-scale structure, we resort to DFT calculations to model the selfassembled nanostructures in the gas phase.…”

Monte Carlo Simulations of the Metal-Directed Self-Assembly of Y-Shaped Positional Isomers

“…Thanks to the holes, a beam of light is introduced into the artistic composition, which shapes the object with a play of chiaroscuro and subtly emphasizes its fragile internal structure [1]. Interestingly, many one-atom-thick molecular assemblies like surface-supported metal-organic networks (SMONs) exhibit a non-trivial, openwork structure [2][3][4][5][6][7]. This is due to the presence of empty cavities (nanopores) within their structure that could differ in shape, spatial distribution, and chirality [8][9][10].…”