Flexible Self-Assembled Molecular Templates on Graphene

Abstract

We report on molecular self-assembly employing a host−guest architecture to pattern the growth of molecules on graphene model surface. Under suitable conditions, the 1,3,5-benzenetribenzoic acid (BTB) selfassembles into an extended honeycomb mesh on graphene on Ir(111), with the molecules in the network being stabilized by linear hydrogen bonds between the carboxylic groups. The nanopores of the mesh are used to host and govern the assembly of cobalt phthalocyanine (CoPC) guest molecules. We characterize the assembled structures structurally and electronically using low-temperature scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. At a coverage higher than one CoPc per pore, the flexible hydrogen bonds of the host network undergo stretching to accommodate two CoPCs in a single pore. When the pores are uniformly doubly occupied, the guest molecules arrange into a herringbone pattern. This minimizes the energy cost associated with the stretching and twisting of the hydrogen bonds between the BTB molecules. The phenomenon observed here can be used to tailor molecular assemblies on graphene to controllably modify its properties. In addition, it allows the formation of guest monomers and dimers stabilized mechanically on the surface of graphene, an archetypical weakly interacting substrate.

Bicomponent Supramolecular Architectures at the Vacuum–Solid Interface

“…44 This review is limited to systems for which both components play a key role in the formation of 2D supramolecular architectures. Therefore, we will not discuss in detail the entrapment of guests in preformed stable supramolecular voids or nanoporous networks 45,46,47,48,49 or systems with admolecules at the top of a supramolecular layer. 50 Although they could be considered bi-or multicomponent supramolecular systems, these types of networks will be briefly mentioned only in the context of perspectives.…”

Comparing the Self‐Assembly of Sexiphenyl‐Dicarbonitrile on Graphite and Graphene on Cu(111)

“…[25] This socalled "band gap problem" is well known in the theoretical modeling community. [26] However,i ts hould be noted that a discrepancy between calculated band gap and STS measure- ments could also be the result of temporary charging of the molecule [27] facilitatedb yad ouble barriert unnel junction. [28,29] In as econd step, we lookeda tt he adsorption of NC-Ph 6 -CN on graphene by comparing an individually adsorbed molecule, au nit cell without shift, and au nit cell that incorporatesashift every fourth molecule ( Figure S3).…”

Molecular assembly on two-dimensional materials

“…(e) Assembly of 1,3,5-benzenetribenzoic acid (BTB) molecules on G/Ir (111) showing long-range ordered network of hexagonal pores stabilized by H-bonding. (f) The flexible network hosts two CoPc molecules in each pore and CoPc assembles in a herringbone pattern; the red lines highlight the arms of the herringbone [114]. Adapted with permission from [72,113,114].…”

“…(f) The flexible network hosts two CoPc molecules in each pore and CoPc assembles in a herringbone pattern; the red lines highlight the arms of the herringbone [114]. Adapted with permission from [72,113,114].…”