Oligo(naphthylene-ethynylene) molecular rods

Molecular rods designed for surface chirality studies have been synthesized in high yields. The molecules are composed of oligo(naphthylene-ethynylene) skeletons and functionalized at their two termini with carboxylic acids and hydrophobic groups. The molecular skeletons were constructed by means of palladium-catalyzed Sonogashira reactions between naphthyl halides and acetylenes. The triazene functionality was used as a protected iodine precursor to allow linear extension of the molecular rods during the syntheses. The carboxylic acid groups in the target molecules were protected as esters during the synthesis to keep the large aromatic molecules soluble during their syntheses. These rigid oligomers were designed to form lamella-like structures when adsorbed on a surface, through which multiple distinguishable surface conformations should be obtainable. Preliminary scanning tunneling microscopy imaging confirmed these properties.