The key importance of controlling supramolecular organic assembly for nanodevice fabrication has been clear since the early 90’s i.e., soon after the dawn of experimental nanotechnology. Most of the earlier modeling work in this field aimed to rationalise the experimentally observed two-dimensional assembly into increasingly complex nanostructures. More than two decades later, modeling techniques now start being able to predict supramolecular assembly with some degree of confidence. Besides significant theoretical advances and increased computing power, this has been enabled by pragmatic approaches that initially rely on experimental feedback to calibrate theoretical tools, and later allow proposing the fabrication of novel structures with desired functionalities to synthetic chemists and STM experts. In this talk I will exemplify the above by describing various instances of 2D self-assembly of organic supramolecular structures supported by metal substrates, focusing on the role played by electrostatic interactions. I will discuss how these structures can be obtained by irreversible as well as reversible molecular charging, achieved by deprotonation or electron transfer, respectively, making it possible to fabricate peculiarly complex, or “tunable”, low-dimensional supramolecular assemblies. A typical application may e.g. start with appropriate choice/synthesis of molecules that will charge up upon adsorption on a target substrate, and extend to predicting the role of co-adsorbed linkage atoms to yield a charged organic salt adlayer with a desired work function value. If time allows, recent attempts of combining DFT calculations, classical molecular dynamics and Monte Carlo techniques to rationalise the results of co-adsorbing more than one chargeable organic species will also be presented, as well as efforts to design thicker organic structures with novel electronic properties.

First-principles modelling of supramolecular organic assembly driven by electrostatic interactions

253rd National Meeting (2017)

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