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A two-dimensional porous network formed from perylene tetracarboxylic diimide (PTCDI) and melamine may be deposited from solution on the surfaces of highly oriented pyrolytic graphite (HOPG), hexagonal boron nitride (hBN) and molybdenum disulphide (MoS2). Images acquired using high resolution atomic force microscopy (AFM) operating under ambient conditions have revealed that the network forms extended ordered monolayers (>1 μm(2)) on HOPG and hBN whereas on MoS2 much smaller islands are observed.

The synthesis and separation of the 1,6- and 1,7- isomers of N,N'-bis(alkyl)diadamantylthio-3,4,9,10-perylenetetracarboxylic acid diimide are reported. Investigations of the structural, electrochemical, spectroscopic, and spectroelectrochemical properties of the isomers reveal a sequence of electrochemically and chemically reversible reduction processes for both isomers. Three X-ray crystal structures are reported including a pair of 1,6- and 1,7-isomers demonstrating the twist of the perylene core in the solid state. Our studies thoroughly characterize the mono- and direduced states of the two isomers allowing unequivocal characterization of the reduced species by UV-vis and IR spectroscopic measurements. EPR studies also allow direct identification of the monoreduced PTCDI species and spectroscopic measurements confirm the delocalization of electronic density around the carbonyl moieties of the reduced species.

The reactions of 3,4,9,10-perylenetetracarboxylic dianhydride with 4,4'-diamino-p-terphenyl and with 2,4,6-tris(4-aminophenyl)-1,3,5-triazine on an Au(111) surface have been followed by low-temperature UHV-STM in the range of 300 to 700 K at coverages of up to one monolayer. Well-ordered, H-bonded structures are observed even after annealing at temperatures up to 470 K, while above 550 K reaction is initiated with evidence of amic acid intermediates. At higher temperatures, full imidisation leads to a covalently linked, surface polyimide networks. There is evidence of gold reconstruction playing a role in the early stages of imidisation and signs of limited order in the final polyimide. With the diamine as precursor, 1D-interconnectivity results, while with the triamine as partner, full 2D-connectivity is possible. In contrast to the situation in the bulk, the intermediate amic acid seems to be less stable and iso-imides are common in the final networks, as witnessed by the conformation of the product and the prevalence of triangular features in the case of the polyimide formed from the triamine precursor.

Surface templating via self-assembly of hydrogen-bonded molecular networks is a rapidly developing bottom-up approach in nanotechnology. Using the melamine-PTCDI molecular system as an example we show theoretically that the network stability in the parameter space of temperature versus molecular coupling anisotropy is highly restricted. Our kinetic Monte Carlo simulations predict a structural stability diagram that contains domains of stability of an open honeycomb network, a compact phase, and a high-temperature disordered phase. The results are in agreement with recent experiments, and reveal a relationship between the molecular size and the network stability, which may be used to predict an upper limit on pore-cavity sizes.

Controlled self-assembly and chemical tailoring of bimolecular networks on surfaces is demonstrated using structural derivatives of 3,4:9,10-perylenetetracarboxylic diimide (PTCDI) combined with melamine (1,3,5-triazine-2,4,6-triamine). Two functionalised PTCDI derivatives have been synthesised, Br(2)-PTCDI and di(propylthio)-PTCDI, through attachment of chemical side groups to the perylene core. Self-assembled structures formed by these molecules on a Ag-Si(111)sqrt3 x sqrt3R30 degrees surface were studied with a room-temperature scanning tunneling microscope under ultrahigh vacuum conditions. It is shown that the introduction of side groups can have a significant effect upon both the structures formed, notably in the case of di(propylthio)-PTCDI which forms a previously unreported unimolecular hexagonal arrangement, and their entrapment behaviour. These results demonstrate a new route of functionalisation for network pores, opening up the possibility of designing nanostructured surface structures with chemical selectivity and applications in nanostructure templating.