title: A molecular approach to self-assembly of trimethylsilylacetylene derivatives on gold.
abstract: We recently discovered that a linear multifunctional trimethylsilylacetylene (TMSA) compound forms long-range and highly stable self-assembled monolayers (SAMs) on reconstructed Au(111). To better understand the interactions governing self-assembly in this new system, we synthesized a series of homologue organosilanes and performed scanning tunneling microscopy (STM) measurements at the Au(111)/n-tetradecane interface. The four TMSA-terminated linear silanes that we synthesized self-assemble in similar ways on gold, with the molecules standing upright on the surface. In contrast, compounds with a slightly modified terminal group but the same polyunsaturated linear chain above the TMSA head do not self-assemble. In particular, substituting a methyl group of TMSA with a more bulky one prevents self-assembly. Removing the C triple bond C triple bond of TMSA or substituting the Si atom by a C atom also hinders self-assembly. Finally, substituting one methyl group of TMSA by a hydrogen atom induces self-assembly but in a different geometry, with the molecules lying flat on the gold surface in a quasi-epitaxy mode. Our molecular approach demonstrates the key role played by the TMSA head in self-assembly, its origin being twofold: 1) the TMSA layers are commensurate to the Au(111) adlattice along the <112> direction, and 2) the C triple bond C triple bond of TMSA activates the Si atom and induces the creation of a surface Si-Au chemical bond. The highly stable TMSA-based SAMs appear then as promising materials for applications in surface modification.
authors.affiliation: CEA-Saclay, LRC Semi-Conducteurs Organiques, DSM/DRECAM/SPCSI, 91191 Gif-sur-Yvette, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Katsonis
authors.forename: Alexandr
authors.initials: A
authors.lastname: Marchenko
authors.forename: Sébastien
authors.initials: S
authors.lastname: Taillemite
authors.forename: Denis
authors.initials: D
authors.lastname: Fichou
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Chouraqui
authors.forename: Corinne
authors.initials: C
authors.lastname: Aubert
authors.forename: Max
authors.initials: M
authors.lastname: Malacria