Modular Bicyclophane-Based Molecular Platforms

The modular synthesis of a series of nanoscale phenylene bicyclophanes with an intraannular orthogonal pillar is described. The compounds are obtained by a Suzuki cross-coupling condensation and are characterized by mass spectrometry and NMR spectroscopy as well as in situ scanning tunneling microscopy at the solid/liquid interface of highly ordered pyrolytic graphite. In addition, their structures and conformations are supported by quantum chemical calculations, also after adsorption to the substrate. A set of two alkyl chain substitution patterns as well as a combination of both were investigated with respect to their ability to form extended 2D-crystalline superstructures on graphite. It shows that not the most densely packed surface coverage gives the most stable structure, but the largest number of alkyl chains per molecule determines the structural robustness to alterations at the pillar functionality. Bicyclophane-based molecular platforms form extended 2D crystalline monolayers after adsorption from solution onto HOPG and contain orthogonal pillars that point towards the supernatant solution phase.image

Automated summary

The modular synthesis of nanoscale phenylene bicyclophanes with an intraannular orthogonal pillar is described in this study. The compounds were characterized by various analytical techniques, and their structures and conformations were further supported by quantum chemical calculations. It was found that the number of alkyl chains per molecule plays a crucial role in determining the structural stability of the assembled molecules on graphite. This study provides important insights into the assembly and characterization of nanomaterials.