The
conformations and the self-assembly process of tetrathiafulvalene
(TTF) derivatives functionalized by lateral alkylthio chains deposited
on graphene/SiC(0001) in ultrahigh vacuum (UHV) and at the solid–liquid
interface are studied by scanning tunneling microscopy (STM). The
study in UHV evidences a “molecular fastener” effect
induced by the increase of van der Waals interactions between the
alkylthio side chains which forces the major part of the molecules
to self-organize in π–π stacked edge-on conformation.
The study at the solid–liquid interface reveals a drastically
different behavior with molecules lying flat on the surface as the
solvent is involved in the stabilization of the molecular layer. This
work raises a burning issue concerning the choice of the deposition
method for graphene functionalization with such molecules