title: STM investigation of substitute effect on oligothiophene adlayer at Au(111) substrate.
abstract: Molecular adlayers of a series of oligothiophenes with carboxylic groups and alkyl substitutes, DTDA, TTDA, QTDA, and PTDA, are investigated by STM at Au(111) surface. The effect of molecular structure including alkyl chain and thiophene backbone on the adlayer structure is revealed. DTDA and TTDA with two and three thiophene rings, self-assembled into highly ordered long-range two dimensional structures via hydrogen bondings, while QTDA with four thiophene rings formed short-range ordered structure with hexagonal symmetry. PTDA with five thiophene rings showed disordered pattern due to its strong molecule-substrate interaction. The results are compared with those on HOPG surface, showing that the molecule-substrate interaction plays an important role in the adlayer formation of these oligothiophenes.
authors.affiliation: Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Wang
authors.forename: Hui-Juan
authors.initials: HJ
authors.lastname: Yan
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Wan
mesh_terms: D001667:Binding, Competitive; D006046:Gold / Q000737:chemistry*; D006860:Hydrogen Bonding; D053768:Metal Nanoparticles / Q000737:chemistry; D016252:Microscopy, Scanning Tunneling / Q000379:methods*; D008956:Models, Chemical; D008968:Molecular Conformation; D015394:Molecular Structure; D036103:Nanotechnology / Q000379:methods; D010316:Particle Size; D015203:Reproducibility of Results; D013379:Substrate Specificity; D013499:Surface Properties; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D013876:Thiophenes; D006046:Gold