Calculated and structural analysis of self-assembly formed by [7]thiaheterohelicene-2,13-carboxaldehyde molecules on Au(111)

Recently, electronic and structural properties of large self-assembled domains of [7]thiaheterohelicene-2,13-carboxaldehyde helicene ([7]TH-dial) molecules on Au(111), Cu(001), and NiAl(110) metal surfaces have been characterized by scanning tunneling microscopy (STM). Several distinct areas of the self-assembled structures can be observed. To describe and explore the morphology and the interactions in these distinct self-assembled nanostructures, we combine results obtained through calculations in a semi-empirical framework and calculated STM images. We revealed that these supramolecular nano-structures, on the metallic substrate, originate from the two orientations P and M of the [7]TH-dial molecules linked them by different processes (head-to-tail, sideways, head-on, and tail-on) through van der Waals interactions. The results presented here provide valuable insights for understanding the intermolecular and substrate-molecule interactions within the self-assembled nano-structures of [7]TH-dial molecules on metallic surfaces.