Supramolecular self-assembly under confinement opens the door to investigate elementary aspects involved in 2D crystallization. Until now, such studies have been ample, mainly due to the limited possibilities to confine the assembling molecules within well-defined nanocompartments. Here, we demonstrate the formation of nanocompartments, called corrals, on graphite with nanoscale control over size, shape and orientation, and discuss how corral parameters impact the resultant self-assembly. Nanocorrals are created by scanning probe lithography, where the tip of a scanning tunneling microscope (STM) is employed to locally expose areas of free graphite on an otherwise densely grafted surface. Upon exposure of the graphite surface, molecules dissolved in an organic liquid above the surface undergo supramolecular self-assembly selectively within these corrals, as observed by STM. However, as opposed to self-assembly on bare graphite, the gradual surface revelation has a pronounced effect on nucleation and growth events. This is reflected by a strong bias of the assembly orientation and domain size. A systematic study on corral size, shape and orientation reveals the importance of geometric and kinetic constraints placed on the self-assembly during the initial stages of corral formation. These constraints eventually allow control over “seeding and growth” processes. The principles discussed in this work are believed to be invaluable tools for future studies on the thermodynamic and kinetic parameters involved in 2D crystallization.

Self-assembly under confinement: Nanocorrals for understanding fundamentals of 2D crystallization

253rd National Meeting (2017)

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