Self-assembly of triazatriangulenium-based functional adlayers on Au(111) surfaces.

Detailed scanning tunneling microscopy studies of the attachment of freestanding molecular functions to Au(111) surfaces via self-assembly of functional molecules based on triazatriangulenium platforms are presented. As shown for molecules with side chains of different length and phenyl, azobenzyl, or azobenzyl derivatives with different terminal groups (iodo, cyano, or dimethyl) as functional units, this approach allows the preparation of very stable, hexagonally ordered adlayers. The intermolecular spacings in these adlayers are independent of the attached functions with the latter being orientated perpendicular to the Au surface. Due to their open structure, adlayers of platforms with attached functional groups exhibit a tendency towards bilayer formation, which can be suppressed by derivatization with appropriate terminal groups.