Freestanding non-covalent thin films of the propeller-shaped polycyclic aromatic hydrocarbon decacyclene

Molecularly thin films are important in material sciences but their use in a wide range of applications requires control over their chemical functionalities, which is difficult to achieve. Here, the authors use decacyclene to form such freestanding and mechanically stable molecular films held together by supramolecular interactions without requiring covalent crosslinking of any kind Molecularly thin, nanoporous thin films are of paramount importance in material sciences. Their use in a wide range of applications requires control over their chemical functionalities, which is difficult to achieve using current production methods. Here, the small polycyclic aromatic hydrocarbon decacyclene is used to form molecular thin films, without requiring covalent crosslinking of any kind. The 2.5 nm thin films are mechanically stable, able to be free-standing over micrometer distances, held together solely by supramolecular interactions. Using a combination of computational chemistry and microscopic imaging techniques, thin films are studied on both a molecular and microscopic scale. Their mechanical strength is quantified using AFM nanoindentation, showing their capability of withstanding a point load of 26 +/- 9 nN, when freely spanning over a 1 mu m aperture, with a corresponding Young's modulus of 6 +/- 4 GPa. Our thin films constitute free-standing, non-covalent thin films based on a small PAH.

Automated summary

Molecularly thin films are crucial in material sciences, but controlling their chemical functionalities is challenging. In this study, the authors successfully formed freestanding and mechanically stable molecular films using decacyclene, held together solely by supramolecular interactions without covalent crosslinking.