Triptycene-Based Self-Assembled Monolayer as a Template for Successive Click Reactions
Saunak Das, Fumitaka Ishiwari, Yoshiaki Shoji, Takanori Fukushima, Michael Zharnikov
Abstract
Triptycene-based molecules represent a promising platform for tripodal monomolecular assembly on solid substrates. The versatility of the approach can be increased significantly if a decoration of the assembled tripods by purpose-specific functional groups will be possible. In this context, the possibility of click reaction between the 10-ethynyl-substituted 1,8,13-trimercaptomethyltriptycene monolayer (EtTripS) on Au(111) and an azide-decorated substituent is tested and additionally verified by a subsequent derivatization reaction. The primary monolayer is shown to exhibit dense molecular packing, tripodal adsorption geometry, and high orientational order, which qualify it well as a template for subsequent reactions. The characteristic spectroscopic fingerprints of the click and derivatization reactions were recorded. The overall impact of these reactions on the work function of the EtTripS-engineered substrate─used as a measure of their efficiency and as an example of functional properties─was well comparable with the effect of the analogous substitution (−CF 3 ) for monodentate monolayers, emphasizing the high potential of the on-surface modification approach.