Building 2D quasicrystals from 5-fold symmetric corannulene molecules

Nano Research - The formation of long-range ordered aperiodic molecular films on quasicrystalline substrates is a new challenge that provides an opportunity for further surface functionalization....     

Hydrogen‐Bonded Molecular Networks of Melamine and Cyanuric Acid on Thin Films of NaCl on Au(111)

Self‐assembly of organized molecular structures on insulators is technologically very relevant, but in general rather challenging to achieve due to the comparatively weak molecule–substrate interactions. Here the self‐assembly of a bimolecular hydrogen‐bonded network formed by melamine (M) and cyanuric acid (CA) on ultrathin NaCl films grown on a Au(111) surface is reported. Using scanning tunneling microscopy under ultrahigh‐vacuum conditions it is demonstrated that it is possible to exploit strong intermolecular forces in the M–CA system, resulting from complementary triple hydrogen bonds, to grow 2D bimolecular networks on an ultrathin NaCl film that are stable at a relatively high temperature of ≈160 K and at a coverage below saturation of the first molecular monolayer. These hydrogen‐bonded structures on NaCl are identical to the self‐assembled structures observed for the M–CA system on Au(111), which indicates that the molecular self‐assembly is not significantly affected by the isolating NaCl substrate.     

From zero to two dimensions: supramolecular nanostructures formed from perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) and Ni on the Au(111) surface through the interplay between hydrogen-bonding and electrostatic metal-organic interactions

Supramolecular self-assembly of the organic semiconductor perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) together with Ni atoms on the inert Au(111) surface has been investigated using high-resolution scanning tunneling microscopy under ultrahigh vacuum conditions. We demonstrate that it is possible by tuning the co-adsorption conditions to synthesize three distinct self-assembled Ni-PTCDI nanostructures from zero-dimensional (0-D) nanodots over one-dimensional (1-D) chains to a two-dimensional (2-D) porous network. The subtle interplay among non-covalent interactions responsible for the formation of the observed structures has been revealed from force-field structural modeling and calculations of partial charges, bond orders and binding energies in the structures. A unifying motif for the 1-D chains and the 2-D network is found to be double N-H??O hydrogen bonds between PTCDI molecules, similar to the situation found in surface structures formed from pure PTCDI. Most interestingly, we find that the role of the Ni atoms in forming the observed structures is not to participate in metal-organic coordination bonding. Rather, the Ni adatoms acquire a negative partial charge through interaction with the substrate and the Ni-PTCDI interaction is entirely electrostatic.