We demonstrate the formation of intermixed phases and self assembled molecular templates on the Au(111) surface. The templates are stabilized by hydrogen bonding between melamine molecules with trigonal symmetry and linear PTCDI (perylene tetra-carboxylic di-imide) molecules. When annealed, these molecules spontaneously form either a chiral intermixed phase or a honeycomb arrangement in which vertexes and edges correspond respectively to melamine and PTCDI molecules. We also observe minority phases with more complex intermolecular junctions. The use of these networks as templates is demonstrated by the controlled capture of fullerenes within the pores of the network to form dimers, hexamers, and heptamers. Our results confirm that bimolecular templates can be realized on a range of substrates.

CONSPECTUS: The arrangement of molecular species into extended structures remains the focus of much current chemical science. The organization of molecules on surfaces using intermolecular interactions has been studied to a lesser degree than solution or solid-state systems, and unanticipated observations still lie in store. Intermolecular hydrogen bonds are an attractive tool that can be used to facilitate the self-assembly of an extended structure through the careful design of target building blocks. Our studies have focused on the use of 3,4,9,10-perylene tetracarboxylic acid diimides (PTCDIs), and related functionalized analogues, to prepare extended arrays on surfaces. These molecules are ideal for such studies because they are specifically designed to interact with appropriate diaminopyridine-functionalized molecules, and related species, through complementary hydrogen bonds. Additionally, PTCDI species can be functionalized in the bay region of the molecule, facilitating modification of the self-assembled structures that can be prepared. Through a combination of PTCDI derivatives, sometimes in combination with melamine, porous two-dimensional arrays can be formed that can entrap guest molecules. The factors that govern the self-assembly processes of PTCDI derivatives are discussed, and the ability to construct suitable target arrays and host-specific molecular species, including fullerenes and transition metal clusters, is demonstrated.

The spontaneous ordering of molecules into two-dimensional self-assembled arrays is commonly stabilized by directional intermolecular interactions that may be promoted by the addition of specific chemical side groups to a molecule. In this paper, we show that self-assembly may also be driven by anisotropic interactions that arise from the three-dimensional shape of a complex molecule. We study the molecule mn 12 o 12 (o 2 CCH 3 ) 16 (H 2 o) 4 (mn 12 (acetate) 16 ), which is transferred from solution onto a Au(111) substrate held in ultrahigh vacuum using electrospray deposition (uHV-EsD). The deposited mn 12 (acetate) 16 molecules form filamentary aggregates because of the anisotropic nature of the molecule-molecule and molecule-substrate interactions, as confirmed by molecular dynamics calculations. The fragile mn 12 o 12 core of the mn 12 (acetate) 16 molecule is compatible with the uHV-EsD process, which we demonstrate using near-edge X-ray adsorption fine-structure spectroscopy. uHV-EsD of mn 12 (acetate) 16 onto a surface that has been prepatterned with a hydrogen-bonded supramolecular network provides additional control of lateral organization.

Monodisperse cyclic porphyrin polymers, with diameters of up to 21 nm (750 C-C bonds), have been prepared using Vernier template-directed synthesis. The ratio of the intrinsic viscosities for cyclic and linear topologies is 0.72, indicating that these polymers behave as almost ideal flexible chains in solution. When deposited on gold surfaces, the cyclic polymers display a new mode of two-dimensional supramolecular organisation, combining encapsulation and nesting: one nanoring adopts a near-circular conformation thus allowing a second nanoring to be captured within its perimeter, in a tightly folded conformation. Scanning tunnelling microscopy reveals that nesting occurs in combination with stacking when nanorings are deposited under vacuum, whereas when they are deposited directly from solution under ambient conditions, there is stacking or nesting, but not a combination of both.The tertiary structures of biological macromolecules are achieved through folding, coiling and multiplex formation, driven by the cooperative effect of many weak interactions 1 . Synthetic monodisperse macromolecules with similar cooperative folding behaviour provide a viable approach to the programmed fabrication of 3D nanostructures [2][3][4][5] . Here we show that cyclic porphyrin polymers, with molecular weights of 30-60 kDa, self-assemble into nested structures on a gold surface. These nested assemblies are only observed when the cyclic polymer has 30 or more repeat units, in keeping with the predictions of a simple geometrical model.The importance of non-covalent self-assembly in biology has inspired many studies of supramolecular organisation on surfaces [6][7][8] , generating 2D assemblies with progressively escalating complexity, from early work on simple structures such as clusters 9 and rows 10,11 , to nanoporous arrays 12,13 , host-guest architectures [14][15][16] , hierarchical arrangements 17 , and multicomponent assemblies [17][18][19] . However, cooperative conformational control has proved difficult to achieve, and this remains a significant gulf between artificial and biological systems. One reason for this difference is that biological macromolecules are much more flexible than the component molecules studied in 2D supramolecular assemblies which are small and, with some exceptions 20,21 , are often treated as quasi-rigid building blocks. Here we illustrate how interactions between large flexible molecules can result in biomimetic cooperative conformational organisation.Studies of linear and cyclic butadiyne-linked zinc porphyrin oligomers (structures l-PN THS and c-PN, Fig. 1) have shown that the distance between the centres of the porphyrin units along the chain is a = 1.35 nm 5,22,23 . Thus the contour length of a linear oligomer, or the perimeter of a nanoring, is Na, where N is the number of porphyrin repeat units. Previously we have shown that nanorings adsorbed on Au(111) exhibit flexibility [24][25][26] , and also that they can act as nanoscale traps for other adsorbed species, such as C 60 guest molecules 2...

Two distinct bimolecular cyanuric acid−melamine intermixed structures, a honeycomb network and a larger superstructure, have been observed on Au(111) using a scanning tunneling microscope under ultrahigh vacuum conditions. The superstructure is formed as a regular array of chiral hexagonal rings of melamine, linked by single molecules of cyanuric acid. These bimolecular networks show both key similarities and differences to related networks studied previously on surfaces and in bulk phases. We also compare our results with networks formed by related molecules on Au(111) and Ag-terminated silicon.